High-entropy prussian blue analogs with 3D confinement effect for long-life sodium-ion batteries

Abstract

Prussian blue analogs (PBAs) have been regarded as competitive cathode materials for sodium-ion batteries due to their low-cost and easy synthesis. Nevertheless, the practical application of PBAs is limited by their intrinsic poor electronic conductivity and structural degradation. Herein, a unique high entropy (HE) Prussian blue Analogs encapsulated by three-dimensional carbon (HE-PBAs@C) was for the first time designed and synthesized by combining the merits of HE and 3D confinement effect originating from carbon wrapping (CW). The HE strategy guarantees the inherent stability of PBAs and promotes accelerated Na⁺ diffusion, while the CW technique serves a dual purpose by enhancing electronic conductivity and mitigating lattice distortion through the 3D confinement effect. As a result, the HE-PBAs@C cathode exhibits impressive electrochemical performance, including high specific capacity (120.2 mA h g⁻¹ at 10 mA g⁻¹), outstanding rate performance (73.0 mA h g⁻¹ at 4 A g⁻¹), excellent capacity retention (80.1% after 4000 cycles at 2 A g⁻¹) and unprecedented stability in the ambient environment. Furthermore, the HE-PBAs@C cathode demonstrates excellent compatibility with both hard carbon (700 cycles 95.4%) and NaTi₂(PO₄)₃ (1000 cycles 98.1%) anodes in full cells, highlighting its promising potential for large-scale energy storage applications.