Lithium-ion batteries: device, operating rules, recommendations on how to properly charge the battery

Most of the battery management habits among users have developed from nickel battery maintenance stereotypes that are not applicable to the next generation of lithium batteries. Technically, they are arranged differently and the electrochemical processes in them have many differences. Therefore, it is very important to know how to charge lithium-ion batteries and remember the peculiarities of their operation.

Modern batteries

The earliest work on lithium batteries was started by the American chemist Gilbert Newton Lewis in 1912. The first working copies appeared in the 70s, but the problems with the possibility of charging them were overcome only 10 years later. The technology was commercialized by Sony Corporation in 1991. Since then, the evolution of lithium cells has not stopped and they continue to improve even now.

Li-Ion battery, like any other, consists of several cells connected to each other. Each of them consists of three functional components: anode (negative electrode), cathode (positive electrode) and layers separating them made of polyethylene or polypropylene. These layers contain pores that can close at temperatures in excess of 130 ° C, thus stopping any chemical reaction if the battery overheats.

Manufacturers also provide various itemsproviding security. Such as, for example, diaphragms that break their tightness in case of overpressure, or corresponding valves.

Although modern batteries are reasonably safe, they still require some vigilance when handling.

Lithium and ion in the title

Lithium is the lightest metalwhich has excellent electrochemical properties. This made it possible to create batteries with a high energy density in relation to mass. For safety reasons, lithium itself is not present in metallic form within battery cells due to its inherent instability. It participates in the reaction in the form of ions, which have the ability to penetrate into the metal lattice of other metals.

The cathode, as a rule, consists of cobalt dioxide, the anode is graphite, and the electrolyte is a conductive salt. Aluminum is used as current collectors for the positive electrode, and copper for the negative one. Lithium ions move from the cathode to the anode during discharge and vice versa during battery charging. Some confusion in understanding the principle of operation can be caused by the name Li-Pol (lithium polymer) batteries. In fact, it is still the same ion battery, only slightly improved.

Features versus nickel-based batteries:

• Large potential difference. Typically 3.6V for Li-ion and 1.2V for NiCd and NiMH.
• Several times larger capacity and power per unit of weight.
• Low self-discharge rate. Approximately 8% at 20 ° C compared to 25% for nickel batteries.
• The ability to accurately determine the state of the residual capacity. The voltage variation with discharge is greater compared to nickel-based batteries.
• The ability to give any shape to the batteries.
• Aging susceptibility. From the moment of production, they begin to lose their ability to store a charge and generate voltage regardless of how they are used.
• Risk of explosion and fire. The heat generated during chemical reactions sometimes gets out of control.

Battery Operation

Despite the fact that the cost of producing lithium batteries has dropped significantly over the past 10 years, they are still expensive enough to be a consumable like AA batteries. Therefore, a simple knowledge of how to store lithium-ion batteries, how to operate and charge them will help you save a lot of money and avoid trouble.

Attention to discharge

It is believed that before charging a lithium battery, it is necessary to completely discharge it. This operating algorithm was relevant for Ni cells. In fact, you never need to fully discharge a Li-ion battery or it may lose capacity. Electronics technology, as a rule, monitors this and informs about the threat of complete discharge in advance. This is also important because the batteries often provide the operation of the equipment, which is damaged by an uncontrolled abrupt interruption of power supply.

In addition, full discharge causes chemical degradation of the components inside the battery. Because of this, subsequent immediate charging can be potentially hazardous. For this reason, smart electronics are given the ability to prohibit work with the battery in order to rule out any incidents. The latter can render the battery unusable. It is not recommended to use more than 95% of the battery capacity whenever possible. Small refills in the case of lithium batteries are the most suitable mode of operation.

Experts believe that you should avoid continuing to charge after the battery is full.. In theory, modern chargers should stop the process in time..

But firstly, different instances of batteries may differ from each other, and secondly, chemical processes inside the elements are rather inert, so the electronics can accurately determine the moment of shutdown not easy.

Charge Cycles

Contrary to popular belief, the number of charge cycles is not the same as the number of attempts to charge the battery. For example, the battery wasted twice from 50% of its capacity. Two charges of a lithium-ion battery at 50% each correspond to one charge cycle, and not two, as it might seem at first glance. Thus, there is no need to wait until the battery is empty.

There are exceptions to all the rules. The mode in which the battery is completely discharged with subsequent continuous charging is called calibration, and is intended to clarify the operation of systems that analyze the state of the battery. It is recommended to do this procedure every month, especially if the battery is subjected to very frequent and small refills.

PerDepth of discharge versus battery life:

• 100% = 300-500 charge cycles;
• 50% = 1200-1500 cycles.

Temperature and storage

It is very important that the battery is loaded within a temperature range of 0 to 45 ° C. Below zero, the rate of chemical reactions slows down, and above 45 ° C, the pressure in the accumulator becomes too high. It is believed that the optimal operating temperature is 20 ° C and this figure is a very important element in the life of a battery.

If we are talking about long-term storage, then in this case the temperature regime is no less relevant. A cool dry place without direct sunlight is ideal. The level of residual charge is extremely important to maintain the performance of lithium batteries.

It is believed that cells charged at half their capacity or slightly less will be in their best shape after rest. This is how batteries are stored in retail outlets.

So, we can conclude that the life cycle of Li-ion batteries can be extended by simple rules: using only high-quality chargers, control over charging and discharging modes, timely calibration, battery overheating protection and hypothermia.