Chinese automaker BYD recently published a patent application for a cathode composite structure aimed at solid-state battery systems. The filing, made public by the China National Intellectual Property Administration on July 28, 2026, outlines a dual-electrolyte approach that combines halide and sulfide materials with the cathode active component. Patent CN202510126712.6 (publication CN122474592A) describes the use of smaller halide electrolyte particles alongside larger sulfide electrolyte particles to form a composite electrode designed to address interface stability during repeated charge–discharge cycles.
BYD Group Chief Scientist Lian Yubo has identified solid-solid interface stability as a primary obstacle to solid-state battery commercialisation, noting that the technology remains in a “tackling stage.” While the new patent details material design and preparation methods, it does not include production validation data, performance specifications, or evidence of vehicle testing.
This disclosure follows several earlier BYD filings in the solid-state domain. In May 2026, BYD applied for a patent covering a composite solid electrolyte membrane composed of inorganic particles embedded within a polymer electrolyte fiber network, highlighting a separate sulfide-based approach. The company has also submitted cathode-related patents such as CN113725405A for a cathode composite structure and CN121237834A for a dual-layer cathode coating.
BYD’s Lithium Battery CTO Sun Huajun has previously stated that the cathode active material proportion in its all-solid-state architecture exceeds 85%, but details on testing conditions and performance results remain undisclosed. While patent publications offer insight into research priorities, they do not confirm whether a technology is production-ready or planned for immediate vehicle integration.
The broader battery industry continues to explore solid-state solutions, though experts emphasize the challenges of scaling lab-level research to high-volume manufacturing. For example, research from the Chinese Academy of Sciences indicates that optimizing sulfide particle size can improve capacity retention in laboratory tests. However, significant technical and production hurdles must be overcome before solid-state batteries achieve large-scale adoption.
Source: CarNewsChina
