Synthesis of controlled-particle-size boehmite for coating lithium-ion battery separators

Abstract

In recent years, the synthesis of inorganic materials with different particle sizes and the structure–activity relationship of inorganic materials have been hot research topics in the materials chemistry field. Here, we report a method for synthesizing boehmite with controlled particle sizes (∼2 μm, ∼1 μm, ∼0.7 μm, ∼0.5 μm and ∼0.3 μm) by adding pseudo-boehmite as crystalline seeds, and explore the effect of the boehmite particle size on lithium-ion battery separator performance. The boehmite/PE separators exhibit good thermal stability, excellent electrolyte wettability, higher ionic conductivity and lower interfacial impedance, compared with pure PE separators. And the best performance of the modified PE separator is achieved when the particle size of coated boehmite is about 0.5 μm. As expected, the LiFePO₄/Li cell with this boehmite/PE separator presents superior cycling stability and rate capacity, and the discharge capacity decreases from 132.8 mA h g⁻¹ to 95.6 mA h g⁻¹ with a capacity retention rate of 72.0% after 1000 cycles at 1C.