Interlayer Spacing-Controlled Na_0.71Co_0.96O₂ with High Pseudocapacitance for Enhanced Sodium Storage

Abstract

Sodium-ion batteries with abundant resources and low cost are considered as a potential candidate for energy application. However, the low rate performance and poor cyclability of cathodes always impede the practical applications of sodium-ion batteries. In this work, we report a facile molten-salt combustion method to fabricate Na0.71Co0.96O2 microplates. When the ratio of sucrose is about 10% in raw materials, the Na0.71Co0.96O2 microplates with a large crystal cell volume and interplanar spacing exhibit a high rate performance of 100.9 mAh g–1 at 1000 mA g–1 and superior cyclability (78.6% retained capacity after 300 cycles at 500 mA g–1). The capacitive contribution analysis and Na+ diffusion coefficient calculation further demonstrate that the large crystal cell volume and interplanar spacing can provide high pseudocapacitance and a rapid sodium-ion diffusion channel in the cathode material during the intercalation/deintercalation process. This strategy can push forward the fabrication of advanced cathodes with high-performance for sodium-ion batteries.