Safety of power lithium-ion batteries

Lithium-ion batteries have been widely used in small portable electronic devices such as mobile phones and laptops. Since the lithium-ion batteries used in these devices are small (1-2Ah or less) and most are single-cell batteries, battery safety concerns are not serious. Even so, in recent years, Japan's Sony has recalled about 100 million laptop batteries from around the world due to safety concerns. Occasionally, there have been incidents of mobile phone batteries exploding and catching fires. Lithium-ion batteries with a single battery capacity of 10Ah or even 100Ah can be used as a power source for electric bicycles, pure electric vehicles, hybrid vehicles, power tools, etc. Security issues have attracted global attention. Safety is a basic requirement for power lithium-ion batteries. According to the different power output performance, power lithium-ion batteries can be divided into energy type and power type. Energy-based power lithium batteries usually have a large capacity and can provide a relatively long-lasting energy supply for power equipment. They are typically used in battery electric vehicles, medium-sized or heavy-duty hybrid vehicles. The total energy of such batteries accounts for a large proportion of the energy distribution of the whole vehicle, often exceeding 10KW. This not only partially absorbs the energy from the vehicle's braking feedback, but also increases the vehicle's driving range in pure electric mode and reduces the total emission of pollutants. Power power lithium batteries usually have a small capacity and can supply instantaneous high-current power supply to power equipment. It is used in power tools and hybrid vehicles to absorb the brake feedback energy and provide instantaneous additional energy for the vehicle's start and acceleration.

In general, the total energy stored by a lithium-ion battery is inversely proportional to its safety. As the capacity of the battery increases, the size of the battery also increases, and its heat dissipation performance becomes worse and worse, so the possibility of accidents will also greatly increase. Regarding mobile phone lithium-ion batteries, the basic requirement is that the probability of safety accidents is less than 1/106, which is also the minimum standard acceptable to the public. However, the safety of large-capacity lithium-ion batteries, especially high-power lithium-ion batteries for automobiles, has been the focus of research. However, with the in-depth research and application of large-capacity lithium-ion batteries, the safety problems of overcharging and short circuit have become increasingly prominent, and have become technical problems that must be overcome for the large-scale application of power lithium-ion batteries. The working conditions of power lithium batteries are harsh. Important safety issues are explosions, burning, battery leaks, and electrical fires caused by battery packs. There are many reasons for battery safety problems, mainly focusing on the safety hazards of overcharging the battery, short circuits inside and outside, and the safety hazards of the battery moving back during the use of the battery pack.

Safety is one of the important obstacles to the practical application of large-capacity lithium-ion batteries.

With the development of lithium-ion batteries and the development of raw materials, the safety of lithium-ion batteries has also made breakthroughs. At present, 10-100ah power lithium-ion batteries and battery packs have passed the industry safety testing standards. The important factors that affect the safety of lithium-ion batteries are electrode materials, electrolytes, manufacturing processes, and usage conditions. With the progress of material science and production technology, electrode materials with high stability performance, choose to include flame retardants or overload protection electrolyte additives, and battery protection circuits to design a well-designed heat dissipation structure and management system to improve the safety of lithium-ion batteries, so large-capacity power lithium-ion batteries to solve the safety problems.