Types of lithium batteries. Li-Ion batteries - truth and myths

Modern mobile phones, laptops, and tablets use lithium-ion batteries. They gradually replaced alkaline batteries from the portable electronics market. Previously, all of these devices used nickel-cadmium and nickel-metal hydride batteries. But their days are over, since Li─Ion batteries have best characteristics. True, they cannot replace alkaline ones in all respects. For example, the currents that nickel-cadmium batteries can produce are unattainable for them. This is not critical for powering smartphones and tablets. However, in the field of portable power tools that draw a lot of current, alkaline batteries are still the way to go. However, work on developing batteries with high discharge currents without cadmium continues. Today we will talk about lithium-ion batteries, their design, operation and development prospects.

The very first battery cells with a lithium anode were released in the seventies of the last century. They had a high specific energy intensity, which immediately made them in demand. Experts have long sought to develop a source based on an alkali metal that has high activity. Thanks to this, the high voltage of this type of battery and energy density were achieved. At the same time, the development of the design of such elements was carried out quite quickly, but their practical use caused difficulties. They were dealt with only in the 90s of the last century.

This happened after a series of accidents. At the time of the conversation, the current consumed from the battery reached its maximum and ventilation began with the emission of flames. As a result, there have been many cases of users suffering facial burns. Therefore, scientists had to refine the design of lithium-ion batteries.

Lithium metal is extremely unstable, especially when charging and discharging. Therefore, researchers began to create a rechargeable battery lithium type without the use of lithium. Ions of this alkali metal began to be used. This is where their name comes from.

Lithium ion batteries have a lower energy density than . But they are safe if charge and discharge standards are observed.

Reactions occurring in a Li─Ion battery

A leap towards the introduction of lithium-ion batteries consumer electronics began to develop batteries in which the negative electrode was made of carbon material. The carbon crystal lattice was very suitable as a matrix for the intercalation of lithium ions. To increase the battery voltage, the positive electrode was made of cobalt oxide. The potential of lite cobalt oxide is approximately 4 volts.

The operating voltage of most lithium-ion batteries is 3 volts or more. During the discharge process on the negative electrode, lithium is deintercalated from carbon and intercalated into cobalt oxide of the positive electrode. During the charging process, the processes occur in reverse. It turns out that there is no metallic lithium in the system, but its ions work, moving from one electrode to another, creating electric current.

Reactions on the negative electrode

All modern commercial models of lithium-ion batteries have a negative electrode made of carbon-containing material. The complex process of intercalation of lithium into carbon largely depends on the nature of this material, as well as the substance of the electrolyte. The carbon matrix on the anode has a layered structure. The structure can be ordered (natural or synthetic graphite) or partially ordered (coke, soot, etc.).

During intercalation, lithium ions push the carbon layers apart, inserting themselves between them. Various intercalates are obtained. During intercalation and deintercalation, the specific volume of the carbon matrix changes insignificantly. In addition to carbon material, silver, tin and their alloys can be used in the negative electrode. They are also trying to use composite materials with silicon, tin sulfides, cobalt compounds, etc.

Reactions on the positive electrode

Primary lithium cells (batteries) often use a variety of materials to make the positive electrode. This cannot be done in batteries and the choice of material is limited. Therefore, the positive electrode of a Li─Ion battery is made of lithiated nickel or cobalt oxide. Lithium manganese spinels can also be used.

Research is currently underway on mixed phosphate or mixed oxide materials for the cathode. As experts have proven, such materials improve electrical characteristics lithium-ion batteries. Methods for applying oxides to the cathode surface are also being developed.

The reactions that occur in a lithium-ion battery during charging can be described by the following equations:

positive electrode

LiCoO 2 → Li 1-x CoO 2 + xLi + + xe -

negative electrode

С + xLi + + xe — → CLi x

During the discharge process, reactions go in the opposite direction.

The figure below schematically shows the processes occurring in a lithium-ion battery during charging and discharging.

Lithium-ion battery design

According to their design, Li─Ion batteries are made in cylindrical and prismatic designs. The cylindrical design represents a roll of electrodes with separator material to separate the electrodes. This roll is placed in a housing made of aluminum or steel. The negative electrode is connected to it.

The positive contact is output in the form of a contact pad at the end of the battery.

Li-Ion batteries with a prismatic design are made by stacking rectangular plates on top of each other. Such batteries make it possible to make the packaging more dense. The difficulty lies in maintaining the compressive force on the electrodes. There are prismatic batteries with a roll assembly of electrodes twisted into a spiral.

The design of any lithium-ion battery includes measures to ensure its safe operation. This primarily concerns the prevention of heating and ignition. A mechanism is installed under the battery cover that increases the resistance of the battery as the temperature coefficient increases. When the pressure inside the battery increases above the permissible limit, the mechanism breaks the positive terminal and the cathode.

In addition, to increase the safety of operation in Li-Ion batteries in mandatory an electronic board is used. Its purpose is to control the charge and discharge processes, to prevent overheating and short circuits.

There are many prismatic lithium-ion batteries currently being produced. They find application in smartphones and tablets. The design of prismatic batteries can often differ between different manufacturers, since they do not have a single unification. Electrodes of opposite polarity are separated by a separator. For its production, porous polypropylene is used.

The design of Li-Ion and other types of lithium batteries is always sealed. This is a mandatory requirement, since leakage of electrolyte is not allowed. If it leaks, the electronics will be damaged. In addition, the sealed design prevents water and oxygen from entering the battery. If they get inside, they will destroy the battery as a result of a reaction with the electrolyte and electrodes. The production of components for lithium batteries and their assembly takes place in special dry boxes in an argon atmosphere. In this case, complex techniques of welding, sealing, etc. are used.

As for the amount of active mass of a Li-Ion battery, manufacturers are always looking for a compromise. They need to achieve maximum capacity and ensure safe operation. The following relation is taken as a basis:

A o / A p = 1.1, where

A o – active mass of the negative electrode;

And n is the active mass of the positive electrode.

This balance prevents the formation of lithium (pure metal) and prevents fire.

Parameters of Li-Ion batteries

Lithium-ion batteries produced today have a high specific energy capacity and operating voltage. The latter is in most cases between 3.5 and 3.7 volts. Energy intensity ranges from 100 to 180 watt-hours per kilogram or 250 to 400 per liter. Some time ago, manufacturers could not produce batteries with a capacity higher than several ampere-hours. Now the problems hindering development in this direction have been eliminated. So, lithium batteries with a capacity of several hundred ampere-hours began to be found on sale.

The discharge current of modern Li─Ion batteries ranges from 2C to 20C. They operate in the ambient temperature range from -20 to +60 Celsius. There are models that are operational at -40 Celsius. But it’s worth saying right away that special battery series work at subzero temperatures. Conventional lithium-ion batteries for mobile phones become inoperable at subzero temperatures.

The self-discharge of this type of battery is 4-6 percent during the first month. Then it decreases and amounts to a percentage per year. This is significantly less than that of nickel-cadmium and nickel-metal hydride batteries. Service life is approximately 400-500 charge-discharge cycles.

Now let's talk about the operating features of lithium-ion batteries.

Operation of lithium-ion batteries

Charging Li─Ion batteries

The charge of lithium-ion batteries is usually combined. First, they are charged at a constant current of 0.2-1C until they reach a voltage of 4.1-4.2 volts. And then charging is carried out at a constant voltage. The first stage lasts about an hour, and the second about two. To charge the battery faster, pulse mode is used. Initially, Li-Ion batteries with graphite were produced and a voltage limit of 4.1 volts per cell was set for them. The fact is that at a higher voltage in the element, side reactions began, shortening the life of these batteries.

Gradually, these disadvantages were eliminated by doping graphite with various additives. Modern lithium-ion cells charge up to 4.2 volts without any problems. The error is 0.05 volts per element. There are groups of Li─Ion batteries for the military and industrial sectors, where increased reliability and long service life are required. For such batteries, the maximum voltage per cell is 3.90 volts. They have a slightly lower energy density, but an increased service life.

If you charge a lithium-ion battery with a current of 1C, then the time to fully gain capacity will be 2-3 hours. The battery is considered fully charged when the voltage increases to maximum and the current decreases to 3 percent of the value at the beginning of the charging process. This can be seen in the graph below.

The graph below shows the stages of charging a Li─Ion battery.

The charging process consists of the following steps:

• Stage 1. At this stage, maximum charging current flows through the battery. It continues until the threshold voltage is reached;
• Stage 2. At a constant voltage on the battery, the charging current gradually decreases. This stage stops when the current decreases to 3 percent of the initial value;
• Stage 3. If the battery is stored, then at this stage there is a periodic charge to compensate for self-discharge. This is done approximately every 500 hours.
  It is known from practice that increasing the charge current does not reduce the battery charging time. As the current increases, the voltage rises faster to the threshold value. But then the second charging stage lasts longer. Some chargers (chargers) can charge a Li─Ion battery in an hour. In such chargers there is no second stage, but in reality the battery at this point is charged by about 70 percent.

As for jet charging, it is not applicable for lithium-ion batteries. This is explained by the fact that this type of battery cannot absorb excess energy when recharging. Jet charging can lead to the transition of some lithium ions to the metallic state (valency 0).

And a short charge well compensates for self-discharge and loss of electrical energy. Charging in the third stage can be done every 500 hours. As a rule, it is performed when the battery voltage is reduced to 4.05 volts on one element. The charge is carried out until the voltage rises to 4.2 volts.

It is worth noting the poor resistance of lithium-ion batteries to overcharging. As a result of the supply of excess charge on the carbon matrix (negative electrode), deposition of metallic lithium may begin. It has very high chemical activity and interacts with the electrolyte. As a result, the release of oxygen begins at the cathode, which threatens an increase in pressure in the housing and depressurization. Therefore, if you charge a Li-Ion element bypassing the controller, do not allow the charging voltage to rise higher than what the battery manufacturer recommends. If you constantly recharge the battery, its service life will be shortened.

Manufacturers pay serious attention to the safety of Li-Ion batteries. Charging stops when the voltage increases above the permissible level. A mechanism is also installed to turn off the charge when the battery temperature increases above 90 Celsius. Some modern models batteries have a switch in their design mechanical type. It is triggered when pressure increases inside the battery housing. The voltage control mechanism of the electronic board disconnects the can from the outside world based on the minimum and maximum voltage.

There are lithium-ion batteries without protection. These are models containing manganese. When recharged, this element helps inhibit lithium metallization and release of oxygen. Therefore, protection is no longer needed in such batteries.

Storage and discharge characteristics of lithium-ion batteries

Lithium batteries are stored quite well and self-discharge per year is only 10-20%, depending on storage conditions. But at the same time, degradation of battery cells continues even if it is not used. In general, all electrical parameters of a lithium-ion battery may differ for each specific instance.

For example, the voltage during discharge changes depending on the degree of charging, current, ambient temperature, etc. The service life of the battery is influenced by the currents and modes of the discharge-charge cycle and temperature. One of the main disadvantages Li-Ion batteries─ this is sensitivity to the charge-discharge mode, which is why they provide a lot different types protection

The graphs below show the discharge characteristics of lithium-ion batteries. They examine the dependence of voltage on discharge current and ambient temperature.

As you can see, as the discharge current increases, the drop in capacity is insignificant. But at the same time, the operating voltage decreases noticeably. A similar picture is observed at temperatures less than 10 degrees Celsius. It is also worth noting the initial drop in battery voltage.

Today for mobile, household appliances, tools use special batteries. They differ in performance characteristics. In order for the battery to work for a long time, without failures, you need to take into account the requirements of the manufacturers of the presented products.

One of the most popular types today are Li-Ion batteries. How to properly charge this type of battery, as well as the features of its operation, should be considered in detail before operating the device.

General characteristics

One of the most common types of batteries today is Li-Ion type. Such devices are relatively low in cost. At the same time, they are undemanding to operating conditions. In this case, the user rarely has a question about how to properly charge a cylindrical Li-Ion 18650 battery or another type.

Most often, the presented batteries are installed in smartphones, laptops, tablets and others. similar devices. The presented batteries are characterized by durability and reliability. They are not afraid of complete discharge.

One of the main features of the presented products is the absence of a “memory effect”. These batteries can be charged at almost any convenient time. The “memory effect” occurs when the battery is not completely discharged. If there was nothing left in it large number charge, over time the battery capacity will begin to decrease. This will lead to insufficient power supply for the equipment. In lithium-ion batteries, the “memory effect” is minimized.

Design

The design of a lithium-ion battery depends on the type of device for which it is intended. For mobile phone a battery called a “jar” is used. It has a rectangular shape and includes one structural element. Its nominal voltage is 3.7 V.

The presented type of battery for a laptop has a completely different design. There may be several individual battery cells in it (2-12 pieces). Each of them has a cylindrical shape. These are Li-Ion 18650 batteries. The manufacturer of the equipment indicates in detail how to charge them correctly. This design includes a special controller. It looks like a microcircuit. The controller controls the charging procedure and does not allow the battery's rated capacity to be exceeded.

Modern batteries for tablets and smartphones also provide a charge control function. This significantly extends the battery life. It is protected from various adverse factors.

Charging Features

When considering how to properly charge Li-Ion batteries of a phone, laptop and other equipment, you need to pay attention to the operating features of the presented device. It should be said that lithium-ion batteries do not tolerate deep discharge and overcharging. This is controlled by a special device that is added to the design (controller).

It is ideal to maintain the charge of the presented type of battery at a level from 20 to 80% of full capacity. The controller monitors this. However, experts do not recommend leaving the device connected to charging all the time. This significantly reduces battery life. In this case, the controller is subject to a constant load. Over time, its functionality may decrease because of this.

At the same time, the controller will also not allow deep discharge. It will simply turn off the battery at a certain moment. This protective function is extremely necessary. Otherwise, the user could accidentally overcharge or over-discharge the battery. Modern batteries also provide high-quality protection against overheating.

Battery operating principle

To understand how to properly charge a Li-Ion battery (new or used), you need to consider the principle of its operation. This will allow you to assess the need to monitor the level of discharge and charge of the device.

Lithium ions in a battery of this type move from one electrode to another. In this case, an electric current appears. Electrodes can be made from different materials. This indicator has a lesser impact on the performance characteristics of the device.

Lithium ions grow on the crystal lattice of the electrodes. The latter, in turn, change their volume and composition. When the battery is charged or discharged, there are more ions on one of the electrodes. The higher the load on metal structural elements that lithium places, the shorter the service life of the device will be. Therefore it is better not to allow high percentage deposition of ions on one or another electrode.

Charging options

Before using the battery, you need to consider how to properly charge the Li-Ion battery of a smartphone, tablet and other equipment. There are several ways to do this.

One of the most correct solutions would be to use a charger. It is supplied complete with electronic equipment by every manufacturer.

The second option is to charge the battery from desktop computer connected to a household network. A USB cable is used for this. In this case, the charging procedure will take longer than when using the first method.

You can perform this procedure using the cigarette lighter in your car. Another less popular method is to charge a lithium-ion battery using a universal device. It is also called "frog". Most often, such devices are used to recharge smartphone batteries. The contacts of this device can be adjusted in width.

Charging a new battery

The new battery must be put into operation correctly. To do this, your phone, tablet or other equipment must be completely discharged. Only when the device turns off can it be connected to the network. The controller will prevent the battery from draining too much. It is he who turns off the device when the battery loses capacity to a predetermined level.

Next, you need to connect the electrical equipment to the network using a standard charger. The procedure is performed until the indicator lights up green. You can leave the device online for a few more hours. This procedure is carried out several times. There is no need to specifically discharge your phone, tablet or laptop.

Normal charging

Knowing how to properly charge Li-Ion batteries can significantly extend the life of the battery. Experts recommend following the correct procedure for this process for a new battery. After this, it is not advisable to completely discharge the battery. When the indicator shows that the battery capacity is only 14-15% charged, it needs to be connected to the network.

At the same time, it is also not recommended to use devices other than the standard one to fill the battery capacity. It has the maximum acceptable current values ​​permissible for specific model batteries. Other options should only be used if absolutely necessary.

Calibration

There is one more nuance that you need to know when studying the question of how to properly charge Li-Ion batteries. Experts recommend periodically calibrating this device. It is held once every three months.

First in normal mode You need to discharge the electrical equipment before turning it off. Next it is connected to the network. Charging continues until the indicator turns green (battery is 100% charged). This procedure must be performed for proper operation controller.

When carrying out such a procedure, the battery circuit board determines the charging and discharging limits. This is necessary to ensure normal operation controller, avoids failures. In this case, the standard charger, which is supplied by the manufacturer complete with a phone, tablet or laptop.

Storage

In order for the battery to work as long and efficiently as possible, you also need to consider the question of how to properly charge a Li-Ion battery for storage. In some cases, a situation may arise when the device for powering equipment is temporarily not in use. In this case, it must be properly prepared for storage.

The battery is charged to 50%. In this state it can be stored for quite a long time. However, the ambient temperature should be around 15 ºC. If it increases, the rate at which the battery loses its capacity will increase.

If the battery needs to be stored for a sufficiently long time, it must be completely discharged and charged once a month. The battery reaches 100% of its specified capacity. Then the device is discharged again and charged to 50%. If this procedure is carried out regularly, the battery can be stored for a very long time. After this, it will be fully usable.

By considering how to properly charge Li-Ion batteries, you can significantly extend the life of this type of battery.

When they talk about lithium batteries or accumulators, most often they don’t even realize that almost a dozen of them have appeared in the last couple of years, each of which is lithium with various additives of others chemical elements, ultimately differing significantly from each other.

Let's look at their types and start with the classics:

Lithium-ion batteries are classic rechargeable batteries in which lithium ions move from the negative electrode to the positive electrode during discharge and back again when charging. Lithium-ion batteries are widely used in consumer electronics. They are one of the most popular types of rechargeable batteries for portable electronics, with one of the best energy densities, no memory effect and slow loss of charge when not in use (low self-discharge).

This series covers cylindrical and prismatic battery sizes. Li-ion has the highest power density of any old type battery. Very light weight and long life cycle makes it ideal product for many solutions.

Lithium titanate (lithium titanate) is a relatively new class of lithium-ion batteries - (more details). It is characterized by a very long life cycle, measured in thousands of cycles. Lithium lead titanate is also very safe and comparable in this regard to iron phosphate. Energy density lower than other lithium-ion current sources and its rated voltage is 2.4V.

This technology features very fast charging, low internal resistance, very high life cycle and excellent endurance (also safety). LTO has found its application mainly in electric vehicles and wristwatches. Recently, it has begun to find application in mobile medical devices due to its high security. One of the features of the technology is that it uses nanocrystals on the anode instead of carbon, which provides a much more efficient surface area. Unfortunately this battery has more low voltage than other types of lithium batteries.

Peculiarities:

• Specific energy: about 30-110Wh/kg
• Energy density: 177 W * h/l
• Specific power: 3,000-5,100 W/kg
• Discharge efficiency: approximately 85%; charging efficiency more than 95%
• Energy-price: 0.5 W/dollar
• Shelf life: >10 years
• Self-discharge: 2-5%/month
• Durability: 6000 cycles to 90% capacity
• Nominal voltage: 1.9 to 2.4 V
• Temperature: -40 to +55°C
• Charging method: using stable D.C., then constant voltage until it reaches the threshold.

Chemical formula: Li4Ti5O12 + 6LiCoO2< >Li7Ti5O12 + 6Li0.5CoO2(E=2.1 V)

Lithium polymer has a higher energy density in terms of weight than lithium-ion batteries. In very thin cells (up to 5 mm), lithium polymer provides high volumetric energy density. Excellent stability in overvoltage and high temperatures.

This series of batteries can be produced in the range from 30 to 23000 mAh, prismatic and cylindrical housing types. Lithium polymer batteries have a number of advantages: greater energy density by volume, flexibility in cell sizes and a wider safety margin, with excellent voltage stability even at high temperatures. Main applications: portable players, Bluetooth, wireless devices, PDA and digital cameras, electric bicycles, GPS navigators, laptops, e-books.

Peculiarities:

• Rated voltage: 3.7V
• Charging voltage: 4.2±0.05V
• Charge current, speed: 0.2-10C
• Discharge voltage limit: 2.5 V
• Discharge speed: up to 50C
• Cycle endurance: 400 cycles

Lithium iron phosphate has good characteristics safety, long service life (up to 2000 cycles), and low production cost. LiFePO4 batteries are well suited for high discharge current applications such as military equipment, power tools, electric bicycles, mobile computers, UPS and solar power systems.

As a new anode material for lithium-ion batteries, lifepo4 was first introduced in 1997 and has been continuously improved to date. It has attracted the attention of experts due to its reliable safety, durability, low environmental impact during disposal, and convenient charging and discharging characteristics. Many experts claim that lifepo4 batteries are by far the best option for autonomously powering electronics.

Lithium sulfur dioxide (Li and SO2 battery) - these batteries have high density energy and good resistance to high power discharge. Such elements are used mainly in military science, meteorology and astronautics.

Lithium sulfur dioxide batteries with a lithium metal anode (the lightest of all metals) and a liquid cathode containing a porous carbon current collector filled with sulfur dioxide (SO2) produce a voltage of 2.9 V and are cylindrical in shape.

Peculiarities:

• High operating voltage, stable throughout most of the discharge
• Extremely low self-discharge
• Performance in extreme conditions
• Wide operating temperature range (-55°C to +65°C)

Lithium manganese dioxide (Li-MnO2 battery) - these batteries have a lightweight lithium metal anode and a solid manganese dioxide cathode, immersed in a non-corrosive, non-toxic organic electrolyte. This type of battery complies with EU RoHS and is characterized by large capacity, high discharge capacity and long service life.

Li-MnO2 is widely used in backup power supplies, emergency beacons, fire alarms, electronic systems access control, digital cameras, medical equipment.

Peculiarities:

• High energy density
• Very stable discharge voltage
• More than 10 year shelf life
• Operating temperature: -40 to +60°С

Lithium thionyl chloride (lithium-SOCl2) batteries feature a lightweight lithium metal anode and a liquid cathode containing a porous carbon current collector filled with thionyl chloride (SOCl2). Li-SOCL2 battery is ideal for automotive devices, medical equipment, and military and aerospace devices. They have the widest operating temperature range from -60 to + 150°C.

Peculiarities:

• High energy density
• Long shelf life
• Wide temperature range
• Good sealing
• Stable discharge voltage

Li-FeS2 batteries

Li-FeS2 batteries and batteries stand for lithium iron disulfide. Information about them will be added later.

Lithium-ion batteries are not as finicky as their nickel-metal hydride counterparts, but they still require some care. Sticking to five simple rules , you can not only extend life cycle lithium-ion batteries, but also increase the operating time of mobile devices without recharging.

Do not allow complete discharge. Lithium-ion batteries do not have the so-called memory effect, so they can and, moreover, need to be charged without waiting for them to discharge to zero. Many manufacturers calculate the life of a lithium-ion battery by the number of full discharge cycles (up to 0%). For quality batteries This 400-600 cycles. To extend the life of your lithium-ion battery, charge your phone more often. Optimally, as soon as the battery charge drops below 10-20 percent, you can put the phone on charge. This will increase the number of discharge cycles to 1000-1100 .
Experts describe this process with such an indicator as Depth Of Discharge. If your phone is discharged to 20%, then the Depth of Discharge is 80%. The table below shows the dependence of the number of discharge cycles of a lithium-ion battery on the Depth of Discharge:

Discharge once every 3 months. Fully charging for a long time is just as harmful to lithium-ion batteries as constantly discharging to zero.
Due to the extremely unstable charging process (we often charge the phone as necessary, and wherever possible, from USB, from an outlet, from external battery etc.) experts recommend completely discharging the battery once every 3 months and then charging it to 100% and keeping it charged for 8-12 hours. This helps reset the so-called high and low battery flags. You can read more about this.

Store partially charged. The optimal condition for long-term storage of a lithium-ion battery is between 30 and 50 percent charge at 15°C. If you leave the battery fully charged, its capacity will decrease significantly over time. But the battery, which has been collecting dust on a shelf for a long time, discharged to zero, is most likely no longer alive - it’s time to send it for recycling.
The table below shows how much capacity remains in a lithium-ion battery depending on storage temperature and charge level when stored for 1 year.

Use the original charger. Few people know that the charger in most cases is built directly inside mobile devices, and the external network adapter It only lowers the voltage and rectifies the current of the household electrical network, that is, it does not directly affect the battery. Some gadgets, such as digital cameras, do not have a built-in charger, and therefore their lithium-ion batteries are inserted into an external “charger”. This is where using an external charger of questionable quality instead of the original one can negatively affect the performance of the battery.

Avoid overheating. Well, the worst enemy of lithium-ion batteries is high temperature - they cannot tolerate overheating at all. Therefore, do not expose mobile devices to direct sun rays, and do not leave them in close proximity to heat sources such as electric heaters. Maximum permissible temperatures, in which it is possible to use lithium-ion batteries: from –40°C to +50°C

Also, you can look

Lithium-ion (Li-ion) batteries are used in most modern tablets, smartphones and laptops, require different maintenance and operating procedures compared to nickel-cadmium (Ni-Cd) and nickel-metal hydride (Ni-MH) batteries used in earlier devices.

In fact, proper care Lithium-ion battery life can be 15 times longer than if used improperly. This article will provide tips on how to maximize the life cycle of expensive lithium-ion batteries in all your portable devices.

Just recently, Windows Secrets Internet portal journalist Fred Langa had to replace a damaged smartphone - and it was his mistake.

The main symptom did not bode well - the phone case was deformed because the body of the device itself began to bend.

Upon disassembly and detailed examination, it turned out that the smartphone’s battery was swollen.

Initially, Fred did not notice any changes: the battery looked more or less normal when looking at it face-on (Figure 1). However, when the battery was placed on a flat surface, it became obvious that its top and bottom edges were no longer flat and parallel to each other. There was a serious bulge on one side of the battery (Figure 2). This bulge caused the phone to bend and become deformed.

The bulging of the battery indicated a serious problem: the accumulation of toxic gases under high pressure inside the battery.

The battery case did its job perfectly, but the toxic gases made the battery look like a tiny pressure cooker bomb just waiting to detonate.

In Fred's case, both the phone and the battery were damaged - it was time to buy a new smartphone.

The saddest thing is that this problem could have been easily prevented. The final part of the article will highlight Fred's mistakes.

To avoid repeating the mistakes of the past with a new smartphone and others lithium-ion devices, such as tablets, laptops, Fred began to seriously research the proper operation and maintenance of lithium-ion batteries.

Fred wasn't interested in extending battery life - these techniques are familiar. Most devices offer manual or automatic modes Energy saving and techniques for adjusting screen brightness, slowing down processor performance, and reducing the number of applications running.

Fred rather focused on battery life extension issues - ways to keep the battery in good working order and extend the battery life to its maximum level.

This article includes a brief thesis statement based on Fred's research. Follow these five tips to ensure your lithium-ion batteries perform well, last, and safely in all your portable devices.

Tip 1: Monitor the temperature and do not overheat the battery

Surprisingly, heat is one of the main enemies of lithium-ion batteries. Causes of battery overheating may include misuse factors, such as the speed and duration of the battery's charging and discharging cycles.

The external physical environment also matters. Simply leaving a device with a lithium-ion battery in the sun or in a closed car can significantly reduce the battery's ability to accept and hold a charge.

The ideal temperature conditions for lithium-ion batteries is a room temperature of 20 degrees Celsius. If the device heats up to 30C, its ability to carry a charge is reduced by 20 percent. If the device is used at 45C, which is easily achievable in the sun or when the device is intensively used by resource-intensive applications, the battery capacity is reduced by about half.

So, if your device or battery becomes noticeably warm during use, try moving to a cooler location. If this is not possible, try to reduce the amount of power consumed by the device by turning off unnecessary applications, services and features, lowering the screen brightness or activating the device's power saving mode.

If this still does not help, turn off the device completely until the temperature returns to normal. For even faster cooling, remove the battery (of course, if the device design allows it) - this way the device will cool down faster due to physical separation from the power source.

By the way, despite the fact that high temperatures are the main problem with lithium-ion batteries, low-temperature operating conditions do not cause serious concern. Low temperatures do not cause long-term damage to the battery, although a cold battery will not be able to produce all the power it could potentially produce at its optimal temperature. The drop in power becomes very noticeable at temperatures below 4C. Most consumer-grade lithium-ion batteries essentially become useless at temperatures near or below freezing.

If a device with a lithium-ion power supply becomes excessively cold for any reason, do not attempt to use it. Leave it unplugged and move it to a warm place (pocket or heated room) until the device reaches normal temperature. As with overheating, physically remove the battery and separate heating will speed up the warm-up process. After the battery warms up to normal temperature, its electrolytic properties will be restored.

Tip 2: Unplug the charger to save battery

Recharge - i.e. Connecting the battery to a high voltage source for too long can also reduce the battery's ability to hold a charge, shorten its service life, or what is called “kill it outright.”

Most consumer-grade lithium-ion batteries are designed to operate at a voltage level of 3.6V per cell, but operate at a higher 4.2V when charging. If the charger supplies high voltage for too long, the internal battery may be damaged.

In severe cases, overcharging can lead to what engineers call “catastrophic” consequences. Even in moderate cases, the excess heat generated during overcharging will create the negative temperature effect described in the first tip.

High-quality chargers can work in concert with the circuitry of modern lithium-ion batteries, reducing the danger of overcharging by reducing the charging current in proportion to the battery's charge.

These properties vary significantly depending on the type of technology used in the battery. For example, when using nickel-cadmium (Ni-Cd) and nickel-metal hydride (Ni-MH) batteries, try to leave them connected to the charger for as long as possible. This is because older types of batteries have high level self-discharge, i.e. they begin to lose a significant amount of stored energy immediately after being disconnected from the charger, even if the portable device itself is turned off.

In fact, a nickel-cadmium battery can lose up to 10 percent of its charge in the first 24 hours after charging. After this period of time, the self-discharge curve begins to level off, but the nickel-cadmium battery continues to lose 10-20 percent per month.

The situation with nickel-metal hydride batteries is even worse. Their self-discharge rate is 30 percent higher than that of their nickel-cadmium counterparts.

However, lithium-ion batteries have a very low self-discharge rate. A good working battery will only lose 5 percent of its charge in the first 24 hours after charging and another 2 percent during the first month after that.

Thus, there is no need to leave the device with a lithium-ion battery connected to the charger until the last moment. To receive best results and extend battery life, disconnect the charger when a full charge is indicated.

New lithium-ion battery devices do not need to be charged extensively before first use (8 to 24 hours of charging is recommended for devices with nickel-cadmium and nickel-metal hydride batteries). Lithium-ion batteries are maximally charged when they indicate 100 percent charge. Extended charging is not necessary.

Not all discharge cycles have the same effect on the condition of the battery. Prolonged and intensive use generates more heat, seriously straining the battery, and shorter, more frequent discharge cycles, on the contrary, extend the battery life.

You might think that increasing small discharge/charge cycles can seriously reduce the life of the power supply. This was only natural for outdated technologies, but does not apply to modern lithium-ion batteries.

Battery specifications can be misleading because... Many manufacturers view the charge cycle as the time required to reach a 100 percent charge level. For example, two charges from 50 to 100 percent are equivalent to one full charge cycle. Likewise, three cycles of 33 percent or 5 cycles of 20 percent are also equivalent to one full cycle.

In short, a large number of small charge-discharge cycles does not reduce the total charge cycles of a lithium battery.

Again, the heat and high load from heavy discharges reduce battery life. Therefore, try to reduce the number of deep discharges to a minimum. Do not allow the battery charge level to drop to values ​​close to zero (when the device turns itself off). Instead, consider the bottom 15 to 20 percent of your battery charge as an emergency reserve—for emergencies only. Get used to replacing the battery if possible or connecting the device to external source power before the battery is completely discharged.

As you know, fast discharge and fast charging are accompanied by the release of excess heat and negatively affect the battery life.

If you have used the device intensively under high loads, allow the batteries to cool to room temperature before connecting to the charger. The battery will not be able to accept a full charge if it is heated.

While charging the device, monitor the temperature of the battery - it should not overheat too much. A hot battery during charging usually indicates that too much current is flowing quickly.

Overcharging is most likely with cheap unbranded chargers using circuits fast charging or with wireless (inductive) chargers.

A cheap charger can be a regular transformer with wires connected to it. Such “silent charges” simply distribute current and practically do not accept feedback from the device being charged. Overheating and overvoltage are very common when using chargers like this, which slowly destroys the battery.

“Fast” charges are designed to provide a minute charge, not a long hour-long charge. There are different approaches to fast charge technology, and not all of them are compatible with lithium-ion batteries. If the charger and battery are not designed to work together, rapid charging can cause overvoltage and overheating. Generally speaking, it is better not to use a charger from one brand to charge a portable device from another brand.

Wireless (inductive) chargers use a special charging surface to restore the battery's charge. At first glance, this is very convenient, but the fact is that such charges emit excess heat even in normal operation (Some kitchen stoves use induction to heat pots and pans).

Lithium batteries not only experience a negative factor in the form of heat, but also waste energy during charging. wireless technology. By its nature, the efficiency of an inductive charger is always lower than its conventional counterpart. Here everyone is free to make their own choice, but for Fred, increased heating and lower efficiency are sufficient factors to refuse such devices.

In any case, the safest approach is to use the included charger recommended by the manufacturer. This is the only guaranteed way to keep temperature and voltage within normal limits.

If an OEM charger is not available, use a low output current charger to reduce the chance of battery damage due to high power being applied quickly.

One low current output power source is the USB port on regular computer. Standard port USB 2.0 provides 500mA (0.5A) current per port, while USB 3.0 provides 900mA (0.9A) per port. For comparison, some dedicated chargers can output 3000-4000mA (3-4A). The low current ratings of USB ports generally ensure safe, normal temperature charging for most modern lithium-ion batteries.

Tip 5: Use a spare battery if possible

If your device allows for quick battery replacement, having a spare battery is a great insurance policy. This not only doubles the operating time of the device, but also eliminates the need to completely discharge the battery or use a fast charge. When the battery charge reaches 15-20 percent, simply replace the dead battery with a spare one, and you will instantly get a full charge of the device without any overheating problems.

A spare battery has other benefits as well. For example, if you find yourself in a situation where the installed battery overheats (for example, due to intensive use of the device or due to high temperature environment), you can replace a hot battery to cool it down faster and still continue to use the device.

Having two batteries eliminates the need for fast charging - you can safely use the device while the battery is slowly charged from a safe power source.

Fred's Fatal Mistakes

Fred suggested that he might have damaged his smartphone battery during a road trip. He used GPS function in the device for navigation during a clear sunny day. The smartphone was left in the sun for a long time in a holder near the dashboard of the car; the brightness of the smartphone was turned on to maximum in order to distinguish the map among the bright rays of the sun.

In addition, all standard background application - e-mail, messenger, etc. were launched. The device used a 4G module to download music tracks and wireless module Bluetoorth for transmitting sound to the headset sound device car. The phone was definitely working under stress.

In order for the phone to receive power, it was connected to a 12V adapter, purchased based on the criteria of low price and availability of the correct connector.

Combination of direct sunlight, high load the processor turned on at maximum screen brightness and the questionable quality of the adapter led to excessive overheating of the smartphone. Fred remembers with horror how hot the device was when pulled out of the holder. This severe overheating was precisely the catalyst for the death of the battery.

Apparently, the problem got worse at night when Fred left the device plugged in all night using a third-party charger without checking when the battery was fully charged.

With his new smartphone, Fred will only use the included charger and spare battery. Fred hopes for a long and safe life for both the battery and the phone, which he plans to achieve with the help of the tips listed.

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