[DigitalToday reporter Jinju Hong] CATL, the world's largest electric vehicle battery company, has disclosed an international patent related to a next-generation solid-state EV battery system, stepping up the commercialisation race.

According to materials released by the World Intellectual Property Organization (WIPO) cited on March 11 by electric vehicle outlet Electrek, CATL filed a patent for a "cathode sheet, solid-state battery cell, battery device and manufacturing method," and the document was published on March 5. The patent describes material structures and operating methods to secure both stability and performance in solid-state batteries.

At the core of the patent is a cathode structure that uses fluorine-containing lithium salts and a sulphide-based solid electrolyte. Fluorine-based lithium salts have stable characteristics even at high temperatures. The sulphide solid electrolyte generates lithium fluoride (LiF) during decomposition to form a solid electrolyte layer. The layer acts as a protective film inside the battery, boosting the stability of the anode and electrolyte, helping extend battery life and improving charging speed.

CATL is already reported to have started pilot production of solid-state batteries with energy density around 500Wh/kg. This is far higher than current commercial lithium-ion batteries and is regarded as an important technology for extending EV driving range and improving safety.

The company is pursuing solid-state battery commercialisation in phases. Wu Kai (카이 우), CATL's chief scientist, is developing the technology with a focus on scaling up 60Ah automotive cells. Small-scale production is expected to begin in 2027, followed by mass production around 2030.

The Chinese government is also moving to prepare systems for solid-state battery commercialisation. China plans to announce national standards for solid-state batteries in July this year. The standards are expected to provide criteria that systematically distinguish liquid batteries, semi-solid batteries and solid-state batteries.

Competition in solid-state batteries is spreading across the global automotive industry. Major companies such as Toyota, Volkswagen and BYD are also developing solid-state batteries on similar timelines. They aim to start pilot production within the next 1 to 2 years and target mass production around 2030.

Real-world vehicle testing has also begun. Mercedes-Benz has succeeded in driving about 1,205 km on a single charge using a Mercedes-Benz EQS test vehicle equipped with a solid-state battery. Markus Schaefer (마르쿠스 셰퍼), Mercedes' chief technology officer, said such battery technology could be a game changer for the EV industry.

Some in the industry also view solid-state batteries as not the only answer for EV batteries. Various battery chemistries, including sodium-ion batteries and LFP (lithium iron phosphate) batteries, are also expected to keep advancing on the back of cost efficiency and stability.

Experts see solid-state batteries as likely to be applied first to premium EV models, then spread to the mass market as the technology matures and production costs fall.