Fabrication Method of Directional Microstructure for High Energy Density, High Power Battery Cathodes

ABSTRACT Rechargeable batteries have attracted significant attention for electric transportation and storage of intermittent renewable energy. Conventional slurry coating makes random electrode microstructure with tortuous ion diffusion pathways that restrict capacity. We present a novel directional ice templating (DIT) method of making ultra‐high mass loading (70 mg cm −2 ) LiNi 0.8 Mn 0.1 Co 0.1 O 2 cathodes containing engineered electrode/electrolyte interface and aligned, fast ion diffusion channels to break the conventional energy‐power trade‐off. We investigated the effects of calendering to reduce electrode porosity while maintaining the interfacial vertical microstructure. Our results show a critical threshold of 30% calendering degree that exhibits the optimal combination of gravimetric and volumetric energy density, fast (dis)charging, and long‐term cycling stability. The porosity of the calendered DIT cathode is compatible with that of the conventional slurry coated cathodes, but exhibits significantly higher energy densities of 367 Wh kg −1 and 779 Wh L −1 when the (dis)charge current is increased to 7 mA cm −2 vs. 102 Wh kg −1 and 215 Wh L −1 for the slurry coated electrodes in pouch cells. Further, we built an electrode processing instrument to demonstrate the scalability of the aqueous DIT method. The developments demonstrate the feasibility of extending the DIT approach toward industrial‐scale sustainable electrode manufacturing for efficient energy storage.