BYD has patented a new composite solid electrolyte membrane, which is an integral part of its “BYD solid state battery development programme”, thereby contributing another piece of technical information to a rapidly emerging trend of sulfide solid-state batteries in China’s battery market. The Chinese patent, with file No. CN121983643A, includes a composite solid electrolyte membrane and its production method, together with solid state battery, battery pack and electrical devices.
BYD Solid State Battery Patent Details
In essence, the BYD solid-state battery patent relates to an electrolyte structure which integrates different solid electrolytes into one assembly, i.e., inorganic solid electrolyte particles and a polymer electrolyte fibre network covering layer. The inorganic electrolyte contains both fine and coarse particles, whereas the polymer electrolyte, made up of a polymer matrix and lithium salts, surrounds certain parts of the inorganic electrolyte.
The architecture focuses on enhancing the performance in two particular aspects, namely ionic conductivity and mechanical strength of the electrolyte membrane.
No information regarding energy densities, charge rate capabilities, cycle lives, cost per unit of manufacturing, or times for commercialization are provided in this patent this narrow technical disclosure does give away the structure but hides the performance that BYD aims to achieve.
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Core Technical Problems in Solid State Battery Development According to BYD’s Chief Scientist
While discussing the patented technology related to BYD’s solid-state batteries, one should not forget that this invention is made against the background of an open technical assessment voiced by the company’s senior executives. In April 2026, BYD chief scientist Lian Yubo reported that his company’s all-solid-state battery research was at a crucial point in time for making a breakthrough, although this process faced serious challenges.
Lian listed solid-solid interface stability and inhibition of lithium dendrites as the two most crucial technological challenges that were currently limiting further advancement. Furthermore, Lian also suggested that the industry needed to develop its approach to whole chain engineering rather than focusing solely on improving individual battery cells – an approach that recognises how much engineering effort goes from one potentially useful patent to a functional BYD solid-state battery.
BYD’s previous releases have mentioned pilot scale production in 2027, which coincides with the development of their third-generation sodium-ion batteries, which aim for an incredible 10,000 charging cycles.
Increasing Competition Around China’s Solid State Batteries
With its application for solid-state battery patents, BYD has entered a highly competitive list of Chinese companies competing to achieve their production goals by 2027. There have been several patent filings from CATL regarding sulfide-based solid-state batteries at similar timelines as BYD. CALB has displayed an all-solid-state battery with a capacity of 60 Ah that offers more than 450 Wh/kg in March 2026.
Chery has announced the development of an all-solid state battery with 60 Ah capacity and a specific energy level of 400 Wh/kg, with integration in the car slated for testing in 2027. Earlier, GAC had revealed the entry into small-scale production for verification tests of its automotive-grade solid-state batteries that were greater than 60 Ah.
The Present Battery Business of BYD is Dominated by LFP Technology
Although BYD is showing strong progress in solid-state batteries, the existing battery business of the company relies on lithium iron phosphate technology only. The cumulative battery installation capacity by BYD stood at 10.49 GWh for April 2026, accounting for 16.8% of the overall market share, lower than 12.84 GWh and 22.5% market share of May 2025.
It is precisely this concentration on LFP that captures BYD’s present-day commercial situation – for now, solid-state technology is still a development project rather than a source of income, while the 2027 pilot production goal marks just the start of commercialization.
