Why did BYD decide to abandon lithium iron phosphate batteries and switch to ternary batteries?

by:CTECHi     2021-07-31

Presumably everyone knows that BYD started with iron phosphate batteries and has been in this field for a long time. However, recently, BYD issued a statement, the content of which was surprising.

It is mentioned in the statement that starting next year, all passenger car parts of BYD will use ternary batteries, and BYD will expand a ternary battery with 10Gwh in Qinghai next year. The output of the battery factory.

The reason why this statement was a big surprise was that BYD had previously touted iron phosphate batteries, saying what iron phosphate batteries are safe, rich in raw materials, Advantages such as easy cost control. At the same time, he expressed great disdain for the ternary battery at that time, saying that the ternary battery was poor in safety and had great safety risks.

However, from now on, BYD’s attitude has changed a lot. The reason may be that the iron phosphate battery can’t be used anymore. I just remembered it now. A ternary battery. Look at what you did before, is it about to slap your face? But it’s okay, who hasn’t made a mistake yet? This kind of courage is commendable for BYD to look back in time.

The so-called ternary battery refers to a lithium-ion battery that uses lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminate as the cathode material. It is characterized by low temperature resistance, high energy density, High charging efficiency and good cycle life. Compared with lithium iron phosphate batteries, its average energy density can be increased by 20% to 50%, but its biggest disadvantage is poor safety.

However, with the driving of policies (subsidies) and the continuous improvement of technology, the safety of ternary batteries will be further enhanced. In terms of market prospects, There is still a lot of room for development.

No matter what, BYD has already made this decision. I hope that BYD can earn some face for the Chinese people. Don’t be looked down upon by Tesla. Finally, I wish BYD good luck. . The next generation of lithium-ion batteries for electric vehicles and mobile phones will choose all-solid-state lithium-ion batteries with higher energy density and better safety. In order to accelerate the research and development of new materials and all-solid-state lithium-ion batteries, the country set up a national key research and development plan for material genome technology for the first time during the 13th Five-Year Plan period. The new concept and technology of intelligent analysis) accelerate the research and development of all-solid-state lithium-ion batteries, and establish a national key special project for all-solid-state battery research and development based on material genome technology. The key special project is led by Professor Pan Feng, School of New Materials, Peking University Shenzhen Graduate School, as the chief scientist Take the lead in organizing 11 units to jointly undertake. An important part of the project's research and development includes the research and development of high-performance all-solid-state lithium-ion batteries and key materials (for example: new solid electrolytes, etc.) and mechanisms (for example: adjustment of the interfaces of solid-state battery materials, etc.) Traditional inorganic ceramic electrolytes have the disadvantages of large interface impedance and poor matching with electrode materials. At present, it is difficult to obtain large-scale application in the field of solid-state batteries. Therefore, the development of new solid-state electrolytes with smaller interface impedance has an impact on the energy density and electrochemical performance of solid-state batteries. Promotion is of great significance.

The long-cycle stability of solid-state batteries and the cycle capacity at different temperatures

Professor Pan Feng’s research group recently Significant progress has been made in the research on solid electrolytes and high-energy-density solid-state batteries. Lithium-containing ionic liquids ([EMI0.8Li0.2][TFSI]) are loaded as guest molecules into porous metal-organic framework material (MOF) nanoparticles In the carrier, a new composite solid electrolyte material was prepared. Among them, lithium-containing ionic liquids are responsible for lithium ion conduction, while porous metal-organic framework materials provide solid carriers and ion transmission channels to prevent the risk of leakage of traditional liquid lithium-ion batteries, and at the same time have certain effects on lithium dendrites. Inhibition of use, so that metal lithium can be directly used as the negative electrode of solid state batteries. The new solid electrolyte material not only has high bulk ionic conductivity (0.3mScm-1), but also has the best interface lithium ion transport performance due to its unique micro-interface wetting effect (nano-wettedeffect), which is compatible with electrode materials. There is a good match between the particles. Due to the above characteristics, the solid-state battery assembled with the new solid electrolyte, lithium iron phosphate positive electrode and lithium metal negative electrode can achieve extremely high electrode material loading (25mgcm-2), and perform well in the temperature range of -20-100°C The electrochemical performance.

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