High-entropy Mn–Prussian blue analogues enable long-term cycling in aqueous sodium-ion batteries through synergistic redox and ion diffusion enhancements
Hao Fu, Jun Yang, Zhiqiang Wu, Ren He, Jianeng Ji, Chunyan Li, Minjie Shi, Edison Huixiang Ang
Abstract
Manganese-based Prussian blue analogues (Mn–PBA) have garnered significant attention due to their exceptionally high specific capacity in aqueous sodium-ion batteries (ASIBs). However, the dissolution of Mn 2+ ions during the charge/discharge process leads to structural degradation, adversely affecting cycle life and limiting practical applications. In this work, a high-entropy strategy is employed to overcome this limitation. The resulting high-entropy Mn–PBA (HE–Mn–PBA), synthesized via a simple co-precipitation method, benefits from entropy stabilization and synergistic effects among multiple metal components, enabling excellent structural integrity during prolonged cycling. As a cathode material, HE–Mn–PBA achieves nearly 100 % capacity retention (116.07 mAh g −1 ) after 200 cycles at 1 A g −1 , along with stable performance over 10,000 cycles. In situ Raman spectroscopy confirms the formation of enhanced and reversible redox-active centers, while kinetic analyses reveal significantly improved Na + diffusion kinetics. Furthermore, a full cell assembled with a polyimide anode delivers a high energy density of 56.11 Wh kg −1 . This high-entropy engineering approach offers a promising pathway to address the stability challenges of Mn-based materials in ASIBs.