Lead-acid or lithium-ion battery? Who will win? Operation, charging, pros and cons of lithium batteries

For a long time, the acid battery was the only device capable of providing electric current to autonomous objects and mechanisms. Despite the high maximum current and minimal internal resistance, such batteries had a number of disadvantages that limited their use in devices that consume large amounts of electricity or in enclosed spaces. In this regard, lithium-ion batteries lack many of the negative qualities of their predecessors, although they do have disadvantages.

Contents

What is a lithium ion battery

The first lithium batteries appeared 50 years ago. Such products were a regular battery, in which a lithium anode was installed to increase the level of electricity output. Such products had very high performance characteristics, but one of the most serious drawbacks was the high probability of lithium ignition when the cathode overheated. Given this feature, scientists eventually replaced the pure element with metal ions, as a result of which safety increased significantly.

Modern li-ion batteries are very reliable and can withstand a large number of charge and discharge cycles. They have minimal memory effect and relatively light weight. Due to these properties, lithium batteries are widely used in many devices. The product can be used as a battery, in the form of batteries for household appliances, and also as a highly efficient traction source of electricity.

Today, such devices have several disadvantages:

• high cost;
• do not like deep discharges;
• may die at low temperatures;
• lose capacity when overheated.

How is li-ion battery production carried out?

Lithium-ion batteries are produced in several stages:

1. Manufacturing of electrodes.
2. Combining electrodes into a battery.
3. Installing the protection board.
4. Installing the battery into the case.
5. Filling with electrolyte.
6. Testing and charging.

At all stages of production, technology and safety measures must be observed, which ultimately allows us to obtain a high-quality product.

Lithium-ion batteries use foil as a cathode with a lithium-containing substance deposited on its surface.

Depending on the purpose of the battery, the following lithium compounds can be used:

• LiCoO2;
• LiNiO2;
• LiMn2O4.

When producing cylindrical power sources of size AA and AAA, the main electrode is rolled into a roll, which is separated from the anode by a separator. With a large cathode area, the film of which has a minimum thickness, it is possible to achieve high energy intensity of the product.

Operating principle and design of a li-ion battery

A lithium ion battery works as follows:

1. When direct electric current is applied to the battery contacts, lithium cations move into the anode material.
2. During the discharge process, lithium ions leave the anode and penetrate into the dielectric to a depth of 50 nm.

In the “life” of a lithium-ion battery, there can be up to 3,000 such cycles, while the battery can deliver almost all the electric current accumulated during the charging process. A deep discharge does not lead to oxidation of the plates, which makes such products stand out compared to acid batteries.

Not all li-ion batteries tolerate deep discharges well. If such a battery is installed in a phone or camera (AAA type), then if it is deeply discharged, the controller board blocks the ability to charge the battery for safety reasons, so it will not be possible to charge it without a special charger. If this is a traction lithium battery for a boat motor, then it will not be at all afraid of a deep discharge.

Unlike finger-type batteries, complex batteries consist of several separate sources of electricity connected in parallel or in series. The connection method depends on what electricity indicator needs to be increased.

Sizes and types of li-ion batteries

Lithium-ion batteries have become widespread. Such sources of electric current are used in various household devices, gadgets and even cars. In addition, industrial lithium-ion batteries with large capacity and high voltage are manufactured. The most popular types of lithium batteries are:

The first two digits of such designations indicate the diameter of the product, the second pair - the length. The last “0” is placed if the batteries are cylindrical in shape.

In addition to cylindrical batteries, the industry produces batteries of the "" type with a voltage of 9v and powerful industrial batteries with a voltage of 12v, 24v, 36v and 48v.

Depending on the elements that are added to the product, the battery case may have the following markings:

• ICR – containing cobalt;
• IMR - - - - manganese;
• INR - - - - nickel and manganese;
• NCR - - - - nickel and cobalt.

Lithium batteries differ not only in size and chemical additives, but primarily in capacity and voltage. These two parameters determine the possibility of their use in certain types of electrical devices.

Where are li-ion batteries used?

Lithium-ion batteries have no alternative where a battery is needed that can deliver almost all of the electricity and perform a large number of charge/discharge cycles without reducing capacity. The advantage of such devices is their relatively low weight, because there is no need to use lead gratings in such devices.

Given their high performance characteristics, such products can be used:

1. As starter batteries. Lithium batteries for cars are becoming cheaper every year, thanks to new developments that reduce production costs. Unfortunately, the price of such batteries can be very high, so many car owners cannot afford such a battery. The disadvantages of lithium-ion batteries include a significant drop in power at temperatures below minus 20 degrees, so in northern regions the operation of such products will be impractical.
2. As traction devices. Due to the fact that lithium-ion batteries can easily withstand deep discharge, they are often used as traction batteries for electric boat motors. If the engine power is not too high, then one charge is enough for 5 - 6 hours of continuous operation, which is quite enough for fishing or taking a boat trip. Traction lithium-ion batteries are also installed on various loading equipment (electric stackers, electric forklifts) operating in enclosed spaces.
3. In household appliances. Lithium-ion batteries are used in various household devices instead of standard batteries. Such products have a voltage of 3.6v - 3.7v, but there are models that can replace a regular salt or alkaline battery with 1.5 Volts. You can also find 3v batteries (15270, ), which can be installed instead of 2 standard batteries.

Such products are used mainly in powerful devices in which conventional salt batteries discharge very quickly.

Rules for using li ion batteries

The service life of a lithium battery is influenced by many factors, knowledge of which will significantly increase the resource. When using this type of battery you must:

1. Try not to let the battery drain completely. Despite the high resistance of the battery to such influences, it is advisable not to squeeze all the “juices” out of it. Particular care should be taken when operating these batteries with UPS and high power electric motors. If the battery is completely discharged, it is necessary to immediately revive it, that is, connect it to a special charger. You can boost the battery even after a long stay in a state of deep discharge, for which you need to perform a high-quality charge for 12 hours, then discharge the battery.
2. Avoid overcharging. Overcharging negatively affects the performance of the product. The built-in controller is not always able to turn off the battery in time, especially when charging is carried out in a cold room.

In addition to overcharging and excessive discharge, the battery should be protected from excessive mechanical stress, which can cause depressurization of the case and fire of the internal components of the battery. For this reason, it is prohibited to send by mail batteries containing more than 1 g of pure lithium.

How to store lithium ion batteries

If there is a need for long-term storage of lithium-ion batteries, then to minimize the negative impact on the products, you must adhere to the following recommendations:

1. Store the product only in a dry, cool place.
2. The battery must be removed from the electrical device.
3. The battery must be charged before storage. The minimum voltage at which internal corrosion processes will not form is 2.5 Volts per 1 element.

Considering the low self-discharge of such batteries, the battery can be stored in this way for several years, but during this period the cell’s capacity will inevitably decrease.

Recycling lithium-ion batteries

Lithium-ion batteries contain substances that are hazardous to health and should never be disassembled at home. After the battery has exhausted its service life, it must be returned for further recycling. At specialized collection points you can receive monetary compensation for an old lithium battery, because such products contain expensive elements that can be reused.

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 the life cycle of 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 needed, and wherever possible, from USB, from a socket, from an external battery, etc.), experts recommend completely discharging the battery once every 3 months and then charging it to 100% and holding it on charge 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 in most cases the charger is built directly into mobile devices, and the external network adapter 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 your mobile devices to direct sunlight or place them near heat sources such as electric heaters. Maximum permissible temperatures at which lithium-ion batteries can be used: from –40°C to +50°C

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• Translation

Death of the Battery: We've all seen it happen. In phones, laptops, cameras, and now electric cars, the process is painful and - if you're lucky - slow. Over the years, the lithium-ion battery that once powered your devices for hours (and even days!) gradually loses its ability to hold a charge. In the end, you will come to terms with it, maybe curse Steve Jobs, and then buy a new battery, or even a new gadget altogether.

But why is this happening? What happens in a battery that causes it to die? The short answer is that due to the damage from prolonged exposure to high temperatures and a large number of charge and discharge cycles, the movement of lithium ions between the electrodes eventually begins to break down.

A more detailed answer that takes us through unwanted chemical reactions, corrosion, the threat of high temperatures and other factors that affect performance starts with an explanation of what happens in lithium-ion batteries when everything is working well.

Introduction to Lithium Ion Batteries

During charging, an electric current moves lithium ions from the cathode to the anode. During discharge (in other words, when the battery is used), the ions move back towards the cathode.

Daniel Abraham, a scientist at Argonne National Laboratory who conducts research into the degradation of lithium-ion cells, compared the process to water in a hydropower system. Water moving up requires energy, but it flows down very easily. In fact, it supplies kinetic energy, Abraham says, in a similar way that the lithium cobalt oxide in the cathode "doesn't want to give up its lithium." Like water moving upward, energy is required to move the lithium atoms out of the oxide and into the anode.

During charging, ions are placed between sheets of graphite that make up the anode. But, as Abraham puts it, "they don't want to be there; the first chance they get they'll move back," like water flowing down a hill. This is detente. A long-life battery will withstand several thousand such charge-discharge cycles.

When is a dead battery really dead?

In cell phones, on the other hand, high power is less important than capacity, or the amount of energy the battery can hold. High capacity batteries last longer on a single charge.

Over time, a battery degrades in several ways that can affect both capacity and power, until eventually it simply cannot perform basic functions.

Think of it in another water analogy: charging a battery is like filling a bucket with tap water. The volume of the bucket represents the battery's capacity, or capacity. The speed at which you can fill it - either by turning the tap on full or in a trickle - is the power. But time, high temperatures, multiple cycles and other factors eventually create a hole in the bucket.

In the bucket analogy, water leaks out. In a battery, the lithium ions are removed, or "tied," Abraham says. As a result, they are deprived of the ability to move between the electrodes. So after a few months, a mobile phone that originally required charging once every couple of days now needs to be charged every 24 hours. Then twice a day. Eventually, too many lithium ions will become “bound” and the battery will not hold any useful charge. The bucket will stop holding water.

What breaks and why

The problem is that the crystal structure can change with each charge and discharge. Ions from apartment A will not necessarily return home, but they may move into apartment B next door. Then ion from apartment B finds his place occupied by this tramp and, without entering into confrontation, decides to move in further down the corridor. And so on.

Gradually, these “phase transitions” in the substance transform the cathode into a new crystalline crystal structure with different electrochemical properties. The exact arrangement of atoms that initially produces the required performance changes.

In hybrid car batteries, which are needed only to supply power when the vehicle accelerates or brakes, Abraham notes, these structural changes occur much more slowly than in electric vehicles. This is due to the fact that in each cycle only a small portion of the lithium ions move through the system. As a result, it is easier for them to return to their original positions.

Corrosion problem

If the bonding material breaks down, it will cause the surface of the current collector to “peele.” If a metal corrodes, it cannot move electrons efficiently.

Corrosion in a battery can result from the interaction of the electrolyte and the electrodes. The graphite anode is “easily released”, i.e. it easily “donates” electrons to the electrolyte. This can result in an unwanted coating on the surface of the graphite. The cathode, meanwhile, is highly "oxidizable," meaning it readily accepts electrons from the electrolyte, which in some cases can corrode the aluminum of the current collector or form a coating on parts of the cathode, Abraham says.

Too much of a good thing

In reality, however, TEI is a very unstable defender. It protects graphite well at room temperature, Abraham says, but at high temperatures or when the battery charge drops to zero (“deep discharge”), TEI can partially dissolve in the electrolyte. At high temperatures, electrolytes also tend to decompose and side reactions are accelerated.

When favorable conditions return, another protective layer will form, but this will eat up some of the lithium, causing the same problems as a leaky bucket. We will have to charge our cell phone more often.

So, we need TEI to protect the graphite anode, and in this case, there really can be too much of a good thing. If the protective layer becomes too thick, it becomes a barrier to lithium ions, which are required to move back and forth freely. This affects power, which Abraham emphasizes is “extremely important” for electric vehicles.

Creating Better Batteries

Meanwhile, engineers at battery and electric car companies are working on housings and thermal management systems in an attempt to keep lithium-ion batteries within a constant, healthy temperature range. We, as consumers, are left to avoid extreme temperatures and deep discharges, and continue to grumble about batteries that always seem to die too quickly.

Among the most modern batteries, lithium ones occupy a special place. In chemistry, lithium is the most active metal.

It has a huge energy storage resource. 1 kg of lithium can store 3860 ampere hours. The well-known zinc lags far behind. His figure is 820 ampere-hours.

Lithium-based cells can produce voltages up to 3.7V. But laboratory samples are capable of producing a voltage of about 4.5V.

Modern lithium batteries do not use pure lithium.

There are currently 3 common types of lithium batteries:

Lithium-ion ( Li-ion). Rated voltage (U nom.) - 3.6V;

Lithium polymer ( Li-Po, Li-polymer or "lipo"). U nom. - 3.7V;

Lithium iron phosphate ( Li-Fe or LFP ). U nom. - 3.3V.

All these types of lithium batteries differ in the cathode or electrolyte material. Li-ion uses a lithium cobaltate cathode LiCoO2, Li-Po uses a gel polymer electrolyte, and Li-Fe uses a lithium ferrophosphate cathode LiFePO 4.

Any lithium battery (or the device in which it operates) is equipped with a small electronic circuit - a charge/discharge controller. Since lithium-based batteries are very sensitive to overcharging and deep discharge, this is necessary. If you pick apart any lithium battery from a cell phone, you can find a small electronic circuit in it - this is the protective controller ( Protection IC ).

If there is no built-in controller (or charge supervisor) in a lithium battery, then such a battery is called unprotected. In this case, the controller is built into the device, which is powered by such a battery, and charging is possible only from the device or from a special charger.

The photo shows an unprotected Li-Po battery Turnigy 2200 mAh 3C 25C Lipo Pack. This battery consists of 3 cells connected in series (3C - 3 cell) of 3.7V each and therefore has a balancing connector. The continuous discharge current can reach 25C, i.e. 25 * 2200 mA = 55000 mA = 55 A! And the short-term discharge current (10 sec.) is 35C!

Lithium batteries, which consist of several cells connected in series, require a complex charger equipped with a balancer. This functionality is implemented, for example, in such universal chargers as Turnigy Accucell 6 and IMAX B6.

A balancer is needed to equalize the voltage across individual cells during charging of a composite lithium battery. Due to differences between cells, some may charge faster and others slower. Therefore, a special circuit for shunting the charging current is used.

This is the wiring for the balancing and power cables of an 11.1V LiPo battery.

As is known, overcharging a lithium battery cell (especially Li-Polymer) above 4.2V can lead to an explosion or spontaneous combustion. Therefore, during charging it is necessary to control the voltage on each cell compound battery battery!

Correct charging of lithium batteries.

Lithium batteries (Li-ion, Li-Po, Li-Fe) are charged by CC/CV method (“constant current/constant voltage”). The method is that first, when the voltage on the element is low, it is charged with a constant current of a certain value. When the voltage on the cell reaches (for example, up to 4.2V - depends on the type of battery), the charge controller maintains a constant voltage across it.

First stage lithium battery charge - CC- implemented through feedback. The controller selects the voltage on the element so that the charge current is strictly constant.

During the first charging stage, the lithium battery accumulates most of the power (60 - 80%).

Second stage charge - CV- begins when the voltage on the element reaches a certain threshold level (for example, 4.2V). After this, the controller simply maintains a constant voltage on the element and gives it the current it needs. Towards the end of the charge, the current decreases to 30 - 10 mA. At this current, the element is considered charged.

During the second stage, the battery accumulates the remaining 40 - 20% of the power.

It is worth noting that exceeding the threshold voltage on a lithium battery can cause it to overheat and even explode!

When charging lithium batteries, it is recommended to place them in a fireproof bag. This is especially true for batteries that do not have a special box. For example, those that are used in radio-controlled models (car, aircraft modeling).

Disadvantages of lithium-ion batteries.

The main and most frightening disadvantage of lithium-based batteries is their fire hazard if the operating voltage is exceeded, overheating, improper charging and illiterate operation. There are especially many complaints regarding lithium-polymer (Li-Polymer) batteries. However, lithium iron phosphate (Li-Fe) batteries do not have such a negative feature - they are fireproof.

Also, lithium batteries are very afraid of the cold - they quickly lose their capacity and stop charging. This applies to Li-ion and Li-Po batteries. Lithium iron phosphate (Li-Fe) batteries are more resistant to frost. Actually, this is one of the positive qualities of Li-Fe batteries.

The disadvantage of lithium batteries is that they require a special charge controller - an electronic circuit. And in the case of a composite battery and balancer.

When deeply discharged, lithium batteries lose their original properties. Li-ion and Li-Po batteries are especially susceptible to deep discharge. Even after restoration, such a battery will have a lower capacity.

If a lithium battery does not “work” for a long time, then first the voltage on it will drop to a threshold level (usually 3.2-3.3V). The electronic circuit will completely turn off the battery cell, and then a deep discharge will begin. If the voltage on the cell drops to 2.5V, this can lead to its failure.

Therefore, it is worth recharging the batteries of laptops, cell phones, and mp3 players from time to time during long periods of inactivity.

Typically, the service life of an ordinary lithium battery is 3 - 5 years. After 3 years, the battery capacity begins to decrease quite noticeably.

What are the types of lithium batteries and their design features?

Lithium batteries have firmly occupied several different niches in the modern market. They are mainly used in all kinds of consumer electronics, portable tools and mobile devices, home appliances, etc. There are even 12 volt lithium batteries for cars. Although they have not yet received widespread use in the automotive industry. The use of lithium batteries in various sectors of the national economy has led to the appearance of many varieties of these batteries on the market. We will look at the main types of lithium batteries in today's article.

We will not write here about the operating principle of Li batteries and the history of their origin. You can read more about it in the article at the given link. You can also read the materials separately about and. And in this material I would like to consider exactly the different types of Li batteries depending on their characteristics and purpose.

So, as for the power and capacity of lithium batteries. The division here is quite arbitrary. In order to produce batteries of different capacities and with different discharge currents, manufacturers change a number of parameters. For example, they regulate the thickness of the layer of electrode mass on the foil (in the case of a roll design). In most cases, this electrode layer is coated with copper (negative electrode) and aluminum (positive) foil. Due to this increase in the electrode layer, the specific parameters of the battery increase.

However, when increasing the active mass, it is necessary to reduce the thickness of the conductive base (foil). As a result, the battery can pass less current without overheating. In addition, an increase in the layer of electrode mass leads to an increase in the resistance of the element. To reduce resistance, more active and dispersed substances are often used for the active mass. Manufacturers “play” with these parameters when producing batteries with certain parameters. A battery cell with thin foil and thick active mass shows high stored energy values. And its power will be low, and vice versa. And this can be adjusted without changing the size of the product.

Batteries with different capacity and discharge current values ​​are obtained by changing the following parameters:

• Foil thickness;
• Separator thickness;
• Material of positive and negative electrode;
• Active mass particle size;
• Electrode thickness.

At the same time, battery models designed for higher power are equipped with current leads of larger sizes and weight. This is done to prevent overheating. Also, to increase the discharge current, various substances are used that are added to the electrolyte or to the electrode mass. Batteries with a large capacity usually have small current leads. They are calculated for a discharge current of up to 2C (usually the charge-discharge current of a battery is indicated by its capacity) and a charging current of up to 0.5C. For high-capacity lithium batteries, these values ​​are up to 20C and 40C, respectively.

High-power lithium battery models are designed to power starters, and high-capacity models are designed to power various portable equipment. As for the development of lithium batteries, manufacturers of all kinds of electronics order them from special companies. They develop them taking into account the proposed conditions, and then place them into mass production. When developing modern lithium batteries, the following parameters are taken into account:

• Capacity;
• Standard and maximum discharge current;
• Dimensions;
• Conditions for location inside the device;
• Operating temperature;
• Resource (number of charge-discharge cycles) and others.

Various Lithium Battery Designs

Based on their design features, lithium batteries can be divided into two categories:

• Housing design;
• Electrode design.

Electrode design

Roll type

In the image below you can see a Li-Ion battery with a roll-type design.

Roll structure elements are manufactured in two types:

• A roll of electrodes is twisted around a virtual plate. One housing can accommodate several rolls connected in parallel;
• Cylindrical. Various heights and diameters.

The roll design is used where a small capacity battery and power are required. This technology has little labor intensity, since the twisting of the electrode strips and the separator is fully automated. The disadvantage of this design is poor heat removal from the electrodes. In fact, heat is removed only through the end of the element.

From a set of electrodes

Lithium batteries assembled from individual electrodes are used in the production of prismatic batteries.

Heat here is also removed from the end of the electrode. Manufacturers are trying to improve heat dissipation by adjusting the composition and dispersion of the active mass.

Housing design

Cylindrical

It is worth paying attention to cylindrical lithium batteries. They are widely used in various household appliances and electronics. Battery cells are especially popular.

Experts cite the absence of volume changes during long-term operation as an advantage of the cylindrical body. This occurs due to the fact that the battery slightly changes its volume during the charging and discharging process. The design of electrodes in such a housing is always roll type. Disadvantages include poor heat dissipation.

Cylindrical lithium batteries may have the following current terminals:

• Screw bournes;
• Regular contact pads.

Where there are higher requirements for current collection, screw borns are used. This is a battery with a high discharge current and large capacity (more than 20 Ah). Numerous tests show that cylindrical lithium batteries with screw-type batteries can withstand currents of no more than 10-15C. And these are the values ​​of short-term load, at which the element quickly overheats. During long-term operation, they can withstand discharge currents of 2-3C. Mainly used in portable power tools.

Battery cells with contact pads are commonly used to form batteries. To do this, they are welded with tape using resistance welding. Sometimes manufacturers already produce elements with petals for independent soldering. Moreover, the type of petals can be different depending on the type of soldering.

The size designation for cylindrical lithium batteries usually includes their dimensions. For example, 18650 lithium-ion cells have a height of 65 mm and a diameter of 18 mm.