Separator and battery

By using a separator design with a porous structure and surface protrusions in lithium-ion batteries, the problem of positive electrode breakage caused by silicon material expansion is solved, improving the cycle stability and safety of the battery, and achieving higher energy density and lower expansion rate.

WO2026144457A1PCT designated stage Publication Date: 2026-07-09ZHUHAI COSMX BATTERY CO LTD
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Patent Information

Authority / Receiving Office
WO · WO
Patent Type
Applications
Current Assignee / Owner
ZHUHAI COSMX BATTERY CO LTD
Filing Date
2025-10-27
Publication Date
2026-07-09

AI Technical Summary

Technical Problem

In lithium-ion batteries, silicon materials expand and contract significantly during charging and discharging, which makes the positive electrode sheet prone to breakage in the step region of the single-sided and double-sided transition zone, affecting the cycle stability and safety of the battery.

Method used

A separator is used, which includes a carrier layer and a polymer layer. The polymer layer has a porous structure and protrusions on its surface. The porous structure has sponge-like buffering properties, and the protrusions can be compressed to absorb the stress generated by the expansion and contraction of the silicon material, thereby reducing the impact on the positive electrode.

Benefits of technology

By using a porous structure and protrusion design, the battery expansion rate is reduced, the cycle stability and safety of the battery are improved, the risk of positive electrode breakage is reduced, and the long-cycle stability and safety performance of lithium-ion batteries are enhanced.

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Abstract

The present disclosure relates to the field of batteries, and in particular, to a separator and a battery. The separator comprises a carrier layer and a polymer layer located on the surface of one or both sides of the carrier layer. The polymer layer is of a porous structure, and the porous structure comprises a first polymer in the form of a continuous phase and a pore structure distributed in the continuous phase of the first polymer, wherein the pore structure is in the form of a discontinuous phase, and the surface of the polymer layer on at least one side is provided with protrusions. The separator of the present disclosure can buffer the expansion and contraction of a negative active material, thereby overcoming the problem of cracking of a positive electrode sheet caused by the expansion and compression of the negative active material, reducing the expansion rate of a battery, and improving the cycle stability of the battery.
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