Battery Cell Buffer Member With Closed Pores for Swelling Control

The buffer member employs a non-uniform porous structure where different regions have different pore densities. The first porous region has a first pore density while the second porous region has a second pore density that differs from the first. This local variation in pore density allows different parts of the buffer member to perform different functions: one region provides better buffering through higher porosity while another region provides structural integrity and controlled electrolyte absorption through lower porosity, thus resolving the contradiction between buffering effect and electrolyte absorption.

The buffer member is constructed as a porous structure with controlled pore densities in different regions. This porous architecture provides high buffering capacity through the compressibility and elasticity of the porous matrix while maintaining low mass due to the void spaces. The first and second porous regions with different pore densities optimize the balance between buffering capacity and mass, enabling the buffer member to effectively accommodate electrode assembly expansion without significantly increasing the overall mass, thus improving mass energy density.

The buffer member features spatially varying pore density with a first porous region and a second porous region having different pore densities. This non-uniform structure creates zones with different electrolyte absorption characteristics. The region with lower pore density absorbs less electrolyte solution, thereby reducing the contact area between the buffer member and electrolyte solution and minimizing side reactions, while still providing effective buffering capacity. This local differentiation resolves the contradiction between space utilization and side reaction prevention.