On January 9, NIO founder William Li announced that the company will mass-produce solid-state batteries, or more accurately, "semi-solid-state batteries," in 2022.
In a media interview, Li Bin emphasized that NIO is not currently using all-solid-state batteries, but rather batteries with liquid electrolytes. Mass production of all-solid-state batteries is still a long way off because the market demand for solid-state batteries is currently very low.
Nevertheless, the news that NIO would "mass-produce solid-state batteries in 2022" quickly spread in the market, and the market paid more attention to solid-state batteries.
Currently, quite a few companies are researching solid-state batteries. So, what are the technological routes in the field of solid-state batteries? And in which direction should power battery companies focus their efforts?
Currently, the main technical routes for all-solid-state batteries can be generally divided into three types: polymer, sulfide, and oxide all-solid-state batteries.
Each technological approach has its advantages and disadvantages. Representative companies in the market include Toyota, which chose the sulfide route; Ilika, which chose the oxide route; and the French company Bolloré, which chose the polymer route.
From the perspective of sulfide technology, Toyota was the first company to enter the research of all-solid-state batteries, and its technological focus is mainly on the sulfide route. Relatively speaking, the sulfide technology route is easier to integrate. However, in terms of chemical performance, oxide solid-state batteries have higher stability, while sulfide-based batteries are relatively poor. Other indicators, such as conductivity and interfacial impedance, are not significantly different.
From the perspective of polymer technology routes, polymer technology routes are not as advantageous as sulfur-based and oxide-based technologies. However, polymer technology routes still have some advantages in terms of integration.
The manufacturing cost of polymer solid-state batteries is also a disadvantage. While Bolloré's solid-state batteries are already used in over 2,000 vehicles, they lack advantages in thermal management. Maintaining proper temperature control is crucial for polymer solid-state batteries, placing high demands on thermal management and imposing a significant burden. This necessitates higher energy and cost resources, increasing the difficulty of mass production.
The market considers sulfur-based batteries to be excellent, with sulfide solid-state batteries showing promising performance indicators and demonstration effects after installation. However, Toyota announced in 2017 and 2018 that it would mass-produce all-solid-state batteries in three years, but mass production has not yet commenced. The main reason for this lack of mass production, or rather, the biggest problem, is the relatively poor chemical stability of sulfur-based batteries. This necessitates the addition of numerous protective measures to the production line, and the design also requires more robust protection methods, including encapsulation.
Regarding the oxide technology route, oxides also have technical challenges, but once these challenges are overcome, oxide all-solid-state batteries will be very cost-competitive in terms of commercialization and large-scale mass production.
Of course, it is too early to tell which technological approach will ultimately prevail.
