Lithium-ion batteries have attracted great interest because of their high capacity, high operating voltage, safety and stability, and no memory effect. And caused a worldwide climax of research. Lithium-ion batteries have thus rapidly developed into industrial applications and are widely used in portable appliances such as mobile phones, video cameras, and notebook computers. This article briefly introduces the development trend of lithium-ion batteries and the safety problem.

The Development Trend of Lithium-ion Batteries

Today, mobile communication terminals such as mobile phones and tablet computers have become the most popular mass consumer electronic products. The battery is the only large-capacity energy storage component in the mobile communication terminal, which provides energy protection for the functions of the terminal.

At the same time, the communication network is becoming more and more mature, and mobile communication terminals will become the focus of the entire communication industry and the electronics industry. In addition, the terminal functions are more powerful, more flexible, and simpler, which leads to higher and higher requirements for the battery.

Because lithium-ion batteries are not on the market for a long time. So there is still a lot of potential for its improvement. As a new type of energy source, lithium-ion batteries still have a lot of room for improvement in performance. Although lithium-ion batteries have many advantages, they also have many shortcomings. For example, the battery cost is high, the current cannot be charged and discharged, and the overcharge resistance is poor.

Therefore, in the future, the improvement direction of the lithium ion battery is:

1. Reducing the cost;
2. Further improving the battery capacity;
3. Further realizing the weight reduction and miniaturization of the battery;

Lithium-ion Battery Safety Issues

Obviously, with the development of lithium-ion battery technology, it will have a broader application prospect. However, reports on fires and even explosions caused by lithium-ion batteries have been common in recent years, and their safety concerns have caused widespread concern. There are mainly the following situations:

1. The General Administration of Quality Supervision, Inspection and Quarantine has also strengthened the quality supervision of batteries. In the supervision and spot checks, it is found that there are many problems in the battery products themselves:
2. The packaging and labeling contents of some products are not standardized, and some products are not packaged or labeled with brand, model, manufacturer name, factory address, etc., which brings inconvenience to consumers during purchase;
3. The battery capacity is imaginary and the use time is short;
4. Some products fail to pass the overcharge protection and short circuit protection, which may damage the battery and the mobile terminal;
5. The low-temperature discharge performance is unqualified, resulting in poor quality outdoor use in the cold winter in the north, and there may be a short use time, and even a serious failure to start.

Causes of Accidents in Lithium-ion Batteries

The Safety of Lithium-ion Batteries is Related to Electrolyte

A lithium-ion battery has a safety accident, mainly caused by a chemical reaction between the electrode and the electrolyte. The solvent of the electrolytic solution is an organic carbonate compound. They are highly reactive and extremely flammable. The positive electrode material of the battery in a charged state is a strong oxidizing compound. The negative electrode material in a charged state is a strongly reducing compound.

In the case of abuse, such as overcharging, overheating and short circuit, the highly oxidizing positive electrode material is generally poor in stability and easily releases oxygen. Carbonates react very easily with oxygen, releasing a lot of heat and gas. The heat generated will further accelerate the decomposition of the positive electrode, generate more oxygen, and promote more exothermic reactions.

At the same time, the activeness of the strongly reducing negative electrode is close to that of metallic lithium, and it immediately burns when it comes into contact with oxygen and ignites the electrolyte, the separator, and the like. Therefore, the safety of lithium-ion batteries can be divided into two levels:

Firstly, the closed lithium-ion battery system is not damaged, but there is a potential for danger. Mainly related to the thermal stability of the material;

Secondly, the battery system has been destroyed, the flammable electrolyte and the oxygen generated inside the battery or the oxygen outside the battery may cause burning or even explosion.

The Safety of Lithium-ion Batteries is Related to Battery Capacity

In addition, the safety of lithium-ion batteries is directly related to battery capacity and size. A battery with a high capacity usually corresponds to a higher heat release amount. Larger batteries are relatively difficult to dissipate heat, and heat is more likely to accumulate, causing thermal runaway. In general, the total energy stored in a lithium-ion battery is inversely proportional to its safety. As the battery capacity increases, the battery volume also increases, and its heat dissipation performance deteriorates. The possibility of an accident will increase dramatically and the security issue will become more prominent.

However, large-capacity lithium-ion batteries are definitely the future development trend. Therefore, how to control the battery quality is what we must do.

How to Control the Quality of Battery

At present, in addition to the partial standards of I EEE for the evaluation of the entire battery system (design, production, finished product testing, etc.), other standards are basically compliance testing standards, that is, the test items specified by the standard. For example, IEC62133, UN38.3, UL1642, etc. are used to simulate the application of the battery in normal use and foreseeable misuse, to ensure the safety of the product under these circumstances. The advantage of this form is that the judgment is clear and the operability is good. It is only necessary to carry out laboratory test on the finished battery to determine whether the standard is met.

Our company has a range of battery testing equipment to choose from, in line with various standards. The details are as follows: