BYD files six more solid-state battery patents
BYD has published six new patents covering key aspects of solid-state battery technology. The filings focus on improving the contact between electrodes and solid electrolytes as the company reportedly targets pilot production of dual-electrolyte cells in 2027.
Four of the new patents concentrate on materials and cell chemistry. One proposes adding an ion-conducting, electrochemically stable interlayer between halide and sulphide electrolytes to prevent unwanted chemical reactions and extend cycle life. Another uses a first solid electrolyte as a buffer layer between the active cathode material and a sulphide electrolyte, aiming to improve stability while limiting heat generation. According to the patent, the active cathode layer should not release more than 117 joules per gram under thermal conditions.
Two further patents focus on the cathode structure itself. One describes a dual-layer composite cathode that combines monocrystalline and polycrystalline cathode materials with different solid electrolytes. BYD says the design seeks to combine the higher structural stability of monocrystalline materials with the superior rate performance of polycrystalline materials.
Another patent proposes a cathode based on three materials, in which lithiated metal oxides and metal sulphides are mixed with a solid electrolyte to reduce interfacial resistance, improve specific capacity and extend cycle life.
The remaining two patents move beyond materials science and towards manufacturing. One introduces ionic liquid wetting agents with a gradient distribution across the electrode to improve ion transport and maintain reliable contact between solid materials. The other defines a quality metric called ‘Re’ for the contact ratio between cathode and electrolyte particles. BYD states that at least 60 per cent of a cathode particle’s perimeter should be in contact with electrolyte particles to improve charging performance, capacity and durability.
The latest patents follow a solid-state battery patent granted by the China National Intellectual Property Administration (CNIPA) in late July covering composite cathode structures. According to Chinese media, BYD plans to start small-scale production of solid-state cells using its dual-electrolyte cathode design in 2027. The first cells are expected to be evaluated in prototype vehicles before any wider deployment. BYD has not officially confirmed the reported production timeline.
These new reports build on the company’s previously disclosed solid-state battery roadmap. Last year, BYD confirmed it had already produced its first solid-state battery cells and planned demonstration vehicles from 2027 before targeting broader commercialisation towards the end of the decade. Earlier this year, the manufacturer also revealed progress in both sodium-ion and solid-state battery research, underlining its strategy of developing multiple next-generation battery chemistries in parallel.
While BYD continues to advance the technology, large-scale production remains a challenge across the industry. In June, CATL Chairman Robin Zeng cautioned that engineering and manufacturing constraints mean solid-state batteries are still several years away from mass-market deployment. Nevertheless, the technology remains a major focus for battery manufacturers.