Boosting sodium storage capability of Prussian blue analogues through in-situ composite integration with carboxylated multi-walled carbon nanotubes

Abstract

Manganese-based Prussian blue analogues (MnHCF) are considered promising candidates for cathode materials in sodium-ion batteries (SIBs), primarily owing to their high redox potential, substantial capacity, and cost-effectiveness. However, the inherent Jahn-Teller distortion and low electronic conductivity of MnHCF lead to structural degradation and poor electrochemical performance. Herein, a MnCoHCF/A-CNT composite material was constructed in situ using a simple co-precipitation reaction by introducing Co as a regulating component and employing a strategy to incorporate carboxylated multi-walled carbon nanotubes (A-CNTs). With the partial substitution of Mn by Co elements enhancing structural stability, along with the conductive network formed by A-CNT boosting electrical conductivity, the MnCoHCF/A-CNT material demonstrates exceptional sodium ion storage capabilities. It demonstrates a discharge capacity of 122.22 mAh g⁻¹ at a current density of 15 mA g⁻¹ and retains a capacity of 81.15 mAh g⁻¹ even at a much higher current density of 1500 mA g⁻¹. Moreover, it exhibits stable cycling performance for over 800 cycles at a current density of 750 mA g⁻¹. This work supplies a convenient strategy for preparing structurally engineered Prussian blue analogues (PBAs) as high-performance SIB cathodes.