Pore Structure Control of Expanded Dickite and Its Application as a Clay Coating Layer on Cross-Linked Nonwoven Fabrics for Lithium-Ion Batteries

Abstract

A composite separator with a tunable pore structure is prepared by coating a porous expanded dickite layer on a cross-linked nonwoven fabric. The expanded dickite is prepared by rapidly calcining the mixture of a dickite-urea intercalation complex and potassium chlorate (KClO3). Moreover, the ratio of the external urea outside the dickite-urea intercalation complex and KClO3 significantly determines the energy released by the reaction of urea and KClO3, and further affects the expansive degree and functional group characteristics of the dickite. When the ratio of external urea to KClO3 is 0.448, the porous expanded dickite with hydroxyl groups shows an average layer gap of 0.212 μm. The composite separator coated with porous expanded dickite has obvious pore morphology characteristics similar to the expanded dickite, and displays a higher porosity (61.6%), electrolyte uptake (0.861 g cm−3), ionic conductivity (3.157 mS cm−1) and discharge capacity (152 mAh g−1) than commercial Celgard 2400. Using this composite separator, LiFePO4/Li cells exhibit an excellent rate capability and acceptable cycling stability, indicating that nonwoven coating by porous expanded dickite is a kind of the high-performance separator for lithium-ion batteries.