The safety of ternary material "high nickel" is still being solved

The ternary battery material refers to a composite electrode material formed by co-melting three kinds of electrode materials and theoretically has the characteristics and advantages of each electrode material.

Lithium nickel cobalt oxide (LiNixCoyMn1-x-yO2) is currently the most mainstream ternary battery material and is considered to be the future development trend. The cobalt salt, the manganese salt, and the nickel salt are used as raw materials, and the ratio of cobalt, manganese and nickel is adjusted to obtain different electrode characteristics.

If you say that the battery material is the hottest now, I am afraid it is a high-nickel ternary material. Compared with lithium iron phosphate and low-nickel ternary materials, high-nickel ternary materials have a greater specific energy advantage due to the higher proportion of nickel. From 333, 532, to 622, to 811 (the ratio of nickel, cobalt, and manganese), in recent years, with the input of research and development, the high-nickel process of ternary materials "cannot stop."

On November 14, 2016, the 5th China Battery Market, jointly sponsored by China Chemical and Physical Power Industry Association and Battery China Network, jointly organized by Shuangdeng Group Co., Ltd. and Yineng (Beijing) Network Technology Co., Ltd. At the annual conference and the first International Summit on Power Battery Applications and the 2nd China Battery Industry Intelligent Manufacturing Seminar, many battery and material enterprises also revealed that the ternary material "high nickel" process accelerated trend.

The high nickel ternary battery material has become the trend of "catching fire"

If the high-nickel ternary material battery is still in the research and development stage of individual manufacturers and academic circles in the past two years, from 2016 onwards, the research and development and production of high-nickel ternary batteries have shown the trend of "catching fire".

Recently, Shilin Huang, president of Ningde Times (CATL), a leading domestic power battery company, said on the relevant occasions that Ningde era will gradually be based on lithium iron phosphate/graphite, ternary, high-nickel ternary/silicon carbon and solid lithium and air metal battery evolution. During the “Thirteenth Five-Year Plan” period, the Ningde era will focus on the development of high-nickel ternary/silicon carbon batteries and strive to achieve the goal of 350Wh/kg. A dedicated team has been organized to ensure that mass production targets are met.

Yiwei Lithium Energy also said on its investor interaction platform that high-nickel NCA (nickel-cobalt-aluminum), NCM622 and NCM811 are the most important development directions of ternary power batteries. The company has completed the planning of NCM622 ternary power battery.

Dangsheng Technology said that with years of experience in research and development and production of high-nickel multi-component positive electrode materials, the company's NCM622 ternary cathode material has been mass-produced and recognized by domestic and international customers, and is applied to the field of new energy vehicle power batteries. The demand for products is in short supply.

According to relevant media surveys, although the current application of ternary battery companies is still NCM333 and NCM523 batteries, NCM622 has entered the material supply chain of some enterprises. With the high nickelization process of the material system, it is expected that the domestic ternary battery companies will start to apply NCM811 and NCA materials next year, and the energy density of the battery cells will move from 200wh/kg to 250-300wh/kg.

Security issues are under continuous resolution

It is well known that the higher the nickel content in the ternary material, the worse the stability of the material and the worse the safety.

At present, although the industry has developed a high-nickel ternary battery material "tune" has been set, in order to maintain its high specific energy while taking into account cycle life and safety, domestic materials and battery companies can be described as painstaking, its safety is still Continue to solve.

According to industry experts, the safety of ternary high-nickel materials can be solved step by step through material modification optimization, surface coating, and adjustment of electrolyte and anode materials.

In terms of material modification, doping some metal ions and non-metal ions in the ternary material lattice can improve the electronic conductivity and ionic conductivity, improve the output power density of the battery, and improve the stability of the ternary material structure; Secondly, coating the surface of the material with some suitable metal compound, lithium salt or some simple substance can also physically isolate the active material from the electrolyte, reduce the occurrence of side reactions, and inhibit the dissolution of the transition metal ions in the electrolyte. The inactive coating layer with a certain mechanical strength can also slow down the collapse of the electrode material structure during long-term circulation; further, the use of an additive to optimize the electrolyte can effectively promote the formation of a high-quality surface film on the surface of the electrode material while suppressing Oxidative decomposition of the electrolyte.

In addition, the industry pointed out that the high nickel ternary material battery manufacturing environment, production equipment, cell manufacturing process and other aspects also put forward higher requirements.

At present, in the safety of high-nickel ternary materials, industry leaders such as BYD and Tianjin Lishen are working hard to solve and improve.

At the 5th China Battery Market Annual Conference and the 1st International Symposium on Power Battery Applications and the 2nd China Battery Industry Intelligent Manufacturing Seminar, Tianjin Lishen introduced the company's high-nickel ternary battery materials research and development in detail production status.

Tianjin Lishen said that in response to the characteristics of high-nickel ternary battery materials, the company has developed a multi-element coating technology to maintain its capacity ratio while improving material properties. In terms of electrolytes, through the use of new antioxidant additives, To improve the cycle performance of the battery, reduce the expansion of high-nickel materials during use; in the battery process, use a new type of adhesive and gradient pure process to improve the cycle life of the battery, reduce the expansion of the silicon material during use, to ensure Battery safety.

BYD staff said on the relevant occasions that in order to completely solve the safety problem of the high-nickel ternary material system, BYD tried to use the silicon material as the battery negative electrode, and made great adjustments to the conductive agent, the connecting agent and the preparation process. On the electrolyte, BYD has increased the testing and development of high temperature resistant high-pressure electrolyte and even solid electrolyte.

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