CATL makes significant progress in the development of its solid-state battery

CATL, the world’s largest supplier of battery cells, is moving steadily forward in the development of the batteries of the future. The company has recently taken two important steps in this direction: the publication of a new international patent, as well as the reservation of a large quantity of a material needed to exploit this patent on an industrial scale.

On March 5, 2026, the World Intellectual Property Organization (WIPO) published CATL’s patent entitled «Positive electrode sheet, solid-state battery cell, battery device, electrical device, positive electrode active material and preparation method». This document describes an approach focused on sulfide-type solid electrolytes. The main innovation lies in the design of the cathode active material, which combines layers of a substrate with transition metal oxides, a cobalt-rich zone and a special coating incorporating lithium salts with fluorine. These salts, with high thermal stability, react with the sulfide electrolyte to generate lithium fluoride (LiF), forming a protective layer that prevents interfacial instability problems and dendrite formation, one of the major obstacles that scientists have encountered so far with this technology.

Although the patent does not mention specific dates, some reports indicate that CATL has already begun pilot production of sulfide-based solid-state cells, with a target energy density of 500 Wh/kg. This level represents a significant leap over conventional lithium-ion batteries. The battery, internally known as Ningde Shidai All-Solid-State, is currently at technology readiness level 4 (laboratory validation), and the company aims to reach levels 7 or 8 by 2027, which would mean cells ready for integration into vehicles in pilot testing.

Looking ahead to what is to come

To prepare for a possible scaling of production, CATL has secured strategic supplies. The company has signed an agreement with Guangdong Jiayuan Technology to reserve up to 626,000 tonnes of copper foil (a key component in the anode) between 2026 and 2028, at an approximate value of €8.4 billion. This massive volume is interpreted as preparation not only for semi-solid batteries, but especially for full solid-state ones.

Despite these advances, CATL maintains a realistic approach. In October 2025, the company acknowledged that, although the main scientific challenges have been resolved, technical and, above all, economic obstacles persist, as sulfide cells are currently between 3 and 5 times more expensive than conventional ones.

CATL has been investing in this technology for more than a decade, with a dedicated R&D team and numerous collaborations with universities and industry. The company is also part of the Chinese CASIP platform – China All-Solid-State Battery Collaborative Innovation Platform – an alliance driven by the Chinese government that brings together competitors such as BYD, CALB, EVE Energy, SVOLT, Gotion and NIO, along with automakers and state funds. The goal of the consortium is to accelerate basic research, develop key technologies, produce vehicles with solid-state batteries and build a competitive supply chain by 2030.