The first experiments with lithium batteries were started back in 1912 by a group of scientists led by G.N. Lewis. But it was only in the early 1970s that the first non-rechargeable lithium batteries appeared. Attempts to develop lithium and lithium-ion batteries up to the 1980s ended in failure. This was due to their security concerns..
Lithium-ion Li-ion batteries, description, features of the device and design, application, aging, main advantages and disadvantages.
Lithium is the lightest of metals. It has excellent electrochemical potential and provides the best energy density per unit mass. Lithium batteries used negative lithium metal plates. These batteries had a higher voltage on each cell and high capacity compared to other types of batteries.
After numerous tests during the 1980s, it became clear that the problem of lithium batteries was “twisted” around lithium electrodes. More precisely, around the activity of lithium. The processes that occurred during aging and wear of the electrodes, in the end, violated the temperature stability of the chemical processes that took place inside the battery.
As a result, the temperature of the element reached the melting point of lithium, and a violent reaction took place, called “ventilation with the release of flame.” In 1991, a large number of lithium batteries were recalled to manufacturers, which were first used as a power source for mobile phones. The reason is when talking, when the current consumption is maximum, a flame was released from the battery, which burned the face of the user of the mobile phone.
Due to the inherent instability of lithium metal, especially during the charging process, research has moved into the field of creating a battery without using it, but using its ions. Although lithium-ion batteries provide slightly lower energy density than lithium batteries, they are nonetheless safe when the correct charge and discharge conditions are observed..
Features of the device of lithium-ion Li-ion batteries.
In 1991, Sony was the first in the world to commercially launch lithium-ion batteries. Other companies followed. Currently, lithium-ion battery manufacturing is a fast-growing and promising market segment..
The energy density of lithium-ion batteries is twice the energy density of standard nickel-cadmium batteries. The improvement achieved by the selection of active electrode materials in the future will increase this ratio up to three times.
In addition to high capacity, lithium-ion batteries have good load characteristics similar to those of nickel-cadmium batteries. They are so undemanding to service that such ease of maintenance is unattainable for other types of batteries..
They have no “memory effect.” For them, control and training cycles are not required to extend the service life. And finally, the self-discharge of lithium-ion batteries, which is half that of nickel-cadmium and nickel-metal hydride batteries, makes them indispensable when used in many devices.
The high voltage on the battery cell allows manufacturers to produce battery packs consisting of just one cell. Such sources are used in many models of modern mobile phones. And simplicity of design simplifies battery production. In the production of high-power batteries consisting of several cells, the very low internal resistance of lithium-ion cells gives a great advantage.
Lithium-ion Li-ion batteries of various designs.
In recent years, several types of lithium-ion batteries have appeared, varying in design. In original Sony batteries, coke (a product of coal processing) was used as the material of the negative plates. Since 1997, in most lithium-ion batteries of various manufacturers (including Sony) there has been a tendency to use graphite.
Graphite plates allow for a more flat discharge voltage characteristic than when using coke-based plates. As a result, storage batteries with graphite plates have a discharge end voltage of 3 V per cell against a discharge end voltage of 2.5 V per cell element for batteries with coke plates. In addition, when using graphite plates in batteries, a higher discharge current is achievable. They heat up less and have less self-discharge..
The device of a lithium-ion Li-ion battery in a cylindrical housing.
As positive plates of lithium-ion batteries, lithium alloys with cobalt or manganese are used. And if plates made of lithium-cobalt alloy last longer, then lithium-manganese plates are much safer and “forgive” operating errors.
Small prismatic lithium-ion batteries for mobile phones with lithium manganese plates have a built-in thermal fuse and thermal sensor. In addition, their production reduces the cost of using a simplified protection scheme, lower cost of raw materials than for the production of batteries with lithium-cobalt plates.
The process of charging a lithium-ion Li-ion battery.
Regarding environmental safety, lithium-ion batteries are significantly safer than lead or cadmium-based batteries. And among lithium-ion batteries, the most safe batteries that use manganese.
Despite all the advantages, such batteries also have disadvantages. They are fragile and require special protection schemes to ensure safe operation. The protection circuit built into the battery case limits the peak voltage on each cell during charging and prevents the voltage from falling below the permissible value during discharge.
In addition, this circuit limits the charging and discharge currents. Monitors battery temperature to avoid overheating. In general, preventive measures prevent the formation of lithium metal during overcharging, the risk of ventilation with the release of a flame or explosion.
Aging lithium-ion Li-ion batteries and accumulators.
Most types of lithium-ion batteries and rechargeable batteries tend to age. For unknown reasons, battery manufacturers are hiding information about this. Sometimes in the technical data they write about the possibility of some decrease in battery capacity after one year, regardless of whether it was used or not.
After 2-3 years, lithium-ion batteries often fail. This is most likely due to the fact that in the substances that make up the batteries, over time, irreversible chemical processes occur that render the batteries unusable.
Storage of lithium-ion Li-ion batteries and accumulators.
Keeping batteries in a cool place slows down the aging process of lithium-ion batteries in the same way as other types of batteries. Manufacturers recommend storing batteries at a temperature of 15 degrees. In this case, the batteries must be recharged..
Long life storage is not recommended for lithium-ion batteries. Moreover, during storage, they must be subject to rotation. That is, they should be periodically turned over. When buying a battery, the consumer must be warned by the manufacturer about the time for its replacement. Unfortunately, information on the release date is often encoded among the digits of the serial number or separately, which does not allow the final consumer to determine the release date without using reference books.
Manufacturers are constantly working to improve the quality of lithium-ion batteries. Approximately every six months they use new or improved chemicals. At such a pace it is difficult, and sometimes impossible to keep track of data on changes in the shelf life and operation.
Features of using lithium-ion Li-ion batteries and accumulators.
The best price / capacity ratios are cylindrical lithium-ion batteries. Most often they are used in mobile computers. If you need a battery in a case thinner than 18 mm, prismatic lithium-ion cells are the best choice, although they are twice as expensive as cylindrical ones. If you need batteries in an ultra-thin case (thinner than 4 mm), lithium-polymer systems are best suited.
Advantages of lithium-ion Li-ion batteries:
High energy density.
Low self discharge.
Missing “memory effect”.
Ease of maintenance.
Disadvantages of lithium-ion Li-ion batteries:
The need for current and voltage protection schemes.
Relatively fast aging. Keeping the battery in a cool place reduces the aging process by about 40%.
Moderate discharge current.
Higher price. 40% higher than nickel cadmium batteries.
The design is not perfected.
Precautions for working with lithium-ion Li-ion batteries and batteries.
When working with lithium-ion batteries and batteries, the following precautions should be observed:
You can not short their conclusions.
Apply reverse polarity voltage.
Only lithium-ion batteries with a protection circuit should be used. The electrolyte of such batteries is highly flammable.
Lithium-ion Li-ion batteries with different types of cases.
The number of types of lithium-ion battery cases is limited by several sizes. Of which the most popular is 18650 (18 – diameter in millimeters, 650 – length, mm). Elements of this size usually have a capacity of 1800 mAh. The capacity of larger elements of size 26650 with a diameter of 26 mm usually starts with 3200 mAh.
Based on the book Battery.