solid state Lithium-ion batteries

SOLID-STATE LITHIUM-ION BATTERIES

It will take time for all-solid-state batteries to be put into use, and semi-solid-state batteries are an intermediate solution for the transition from liquid-state batteries to all-solid-state batteries. All-solid-state batteries have the advantages of high energy density and good safety performance, but now the implementation of all-solid-state batteries will encounter challenges, including the following three aspects:

(1) Solid-solid interface contact leads to large internal resistance of the battery; 
(2) The ionic conductivity is not high, and the conductivity of the existing solid-state electrolyte is 1-2 orders of magnitude lower than that of the liquid electrolyte; and 
(3) Due to the lack of commercialisation (inorganic solid-state electrolytes and raw materials have not yet been mass-produced to form a supply chain), the cost of all-solid-state electrolytes is higher than that of traditional liquid lithium-ion batteries, and the product yield is low.

Semi-solid batteries are an intermediate solution for the transition to all-solid batteries. 
(1) Semi-solid batteries retain a certain amount of electrolyte, and their cycle performance and rate performance are better than those of all-solid batteries; 
(2) Semi-solid battery electrode materials are soaked in electrolyte, which can improve the problem of low conductivity of solid-state batteries; and 
(3) The current cost of semi-solid batteries is slightly higher than that of traditional lithium batteries, but is at a lower position than all-solid-state batteries.

Although Japan, the United States, and South Korea were relatively early in the research and development and industrial layout of all-solid-state batteries, China took the lead in realising the mass production of solid-state batteries because it chose the route of solid-liquid hybrid batteries.

The solid-state battery production lines of enterprises such as Ganfeng Lithium Co., Ltd, Qingtao Energy Development Co., Ltd and Weilan New Energy have been completed and put into production. From 2022 to 2025, a number of leading semi-solid battery companies in China will gradually release car-grade batteries for auto companies. For example, Dongfeng will release E70 model, Lantu will release Chasing Wind and other models, and NIO will release ET7 model equipped with semi-solid batteries. During the iterative process of solid-state batteries, the liquid electrolyte content will drop from 20wt% to 0wt%, and the lithium content of the anode material of the battery will gradually increase until it is replaced by metal lithium sheets. The battery density is expected to gradually increase to 500Wh/kg.


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