BYD files a patent for batteries with cells submerged directly in cooling liquid

BYD has filed a patent application for a battery system in which the cells sit submerged directly in the cooling liquid. The document, numbered CN 122868832 A, was published on October 5, 2026 by the China National Intellectual Property Administration (CNIPA). It was filed in March 2025 under the title "Battery cabinet and energy storage equipment."

What immersion cooling means

Many batteries today use indirect cooling: coolant flows through aluminum plates pressed against the modules, and heat has to pass through the cell casing and other layers before it reaches the coolant. BYD's and CATL's current storage systems are also liquid-cooled without the coolant touching the modules directly.

With immersion cooling, the modules sit directly in a dielectric fluid, which doesn't conduct electricity. Heat moves from the cells straight into the fluid, over a much shorter path. BYD mentions hydrocarbon- or ester-based fluids rather than ordinary coolant.

The problem the patent solves

If the batteries sit in liquid, the electrical parts have to stay dry. The patent splits the cabinet into two separate compartments:

• at the top, a dry compartment with the electrical equipment;
• at the bottom, a liquid-filled compartment holding the cell modules.

Power and signal leads leave the liquid compartment through its top, not through the walls or floor. The fluid pressure is lower there, and the exit point has less contact with the liquid. According to the abstract, this reduces the risk of leaks, improves sealing and makes the cabinet safer.

For storage, not for cars

The patent covers battery cabinets for energy storage and doesn't mention any vehicle application. The idea that this is a faster-charging car battery isn't supported by the document. The application is still under examination, and BYD hasn't announced any production plans.

For BYD's latest sales numbers, see our article on its September record.