About the development of power cells

The range and safety of electric vehicles have always been the focus of attention of the industry and users. In order to improve the performance of power vehicles, major companies and research institutes have stepped up their research efforts in the battery field and strived to take the lead in the new energy vehicle market.

There are many breakthroughs in mileage

Toyota and Nissan, two of Japan's biggest electric car makers, have released their latest technology results in the power cell sector. The two companies 'new generation of intensive energy storage power sets can provide longer driving forces for electric and hybrid vehicles.

Toyota is working on replacing lithium electrolytes with magnesium electrolytes currently used in lithium ion batteries. Toyota believes that magnesium has two major benefits over lithium. First, magnesium allows intensive energy storage. In addition, lithium is an unstable metal element that is prone to fire and magnesium is relatively safer. The company's magnesium-based chemical batteries will be available within the next 20 years.

Nissan is seeking an additive to improve the performance of current lithium batteries and expand energy storage capacity. Nissan's technology is to add an additive called amorphous silicon monoxide to the battery to increase the energy storage capacity of lithium-ion batteries. This chemical allows the battery to retain more lithium ions, thereby improving the overall performance of the battery.

Domestic scientific research institutions have also made recent progress in this regard. In March this year, Tangyongbing and his research team of the Shenzhen Institute of Advanced Technology of the Chinese Academy of Sciences announced the latest results of the "New High Energy Density Aluminum Graphite Double Ion Battery Technology." This new type of battery adjusts the positive and negative poles of traditional lithium ion batteries and uses aluminum foil as both a negative electrode material and a negative collector fluid. The principle of the battery is different from that of traditional lithium-ion batteries: during the charging process, anion intercalation reactions occur in the positive graphite, while the aluminum negative electrode undergoes aluminum-lithium alloying reaction, and the discharge process is the opposite. This new reaction mechanism not only significantly increases the operating voltage of the battery, but also significantly reduces the quality, volume, and manufacturing costs of the battery, thus improving the energy density of the battery. According to preliminary estimates, the range of 500 Kg Al-graphite batteries can reach about 550 kilometers. Compared with traditional lithium power technology, this type of battery has a clear advantage, not only reducing production costs by about 40-50 %, but also increasing energy density by at least 1.3-2 .0 times.

In addition, a number of companies and institutions have intensified their research on graphene lithium batteries to break through the problem of mileage.

Security issues to be resolved

In the eager pursuit of the high energy density of the power battery, its safety can not be underestimated. Recently, many electric bus fires and battery factory explosions have caused people to pay great attention to the safety of lithium electricity.

Part of the reason for the safety hazards of power cells is due to the problem of cell unit balance in Series batteries. Due to the differences between batteries in the process of charging and discharging, batteries can cause excessive charging or excessive discharge. Excessive charging and discharging can lead to the burning and explosion of batteries.

In addition, the study shows that for example, when the battery is full of electricity, its positive material composition is lithium cobalt oxide in the delithium state, and the negative electrode is lithium carbon. Lithium cobalt acid decomposes at high temperatures to release oxygen, and the chemical reaction activity of lithium carbon is basically similar to that of metal lithium. So if combustion occurs, it is basically the same as the combustion of metallic lithium in an oxygen-rich environment, which will have very serious consequences.

Therefore, it is extremely important to equip the power battery with a high-quality BMS battery management system. As an important link between secondary cells and electrical appliances, BMS integrates the monitoring and management of cells or batteries to achieve important functions such as real-time monitoring, automatic equilibrium, and intelligent charging and discharging of cells, thus ensuring the safety and reliability of cells or batteries., And output power in the best state.

At present, the country is developing the relevant standards of battery management system, which will promote the progress of the work on the safety of power batteries in China.

The page contains the contents of the machine translation.