Stable Manganese-Based High-Entropy Prussian Blue for Enhanced Sodium-Ion Storage
Congcong Li, Yang Xiao, Dingyi Zhang, Xinyao Yuan, Jun Xiao, Yufei Zhao, Hong Gao, Hao Liu
Abstract
Prussian blue (PB) and its analogs (PBAs) are considered ideal cathode materials for sodium-ion batteries (SIBs) due to the following merits, including high redox potential, simple synthesis methods, and excellent structural stability. Herein, we synthesized a high-entropy PB cathode material, Na1.20Mn0.38Fe0.15Ni0.14Co0.15Cu0.16[Fe(CN)6]0.82□0.18·0.38H2O (HE-HCF), through a facile co-precipitation method. The five transition metals in HE-HCF have similar atomic sizes and electronegativity, collectively occupying the high-spin Fe-HS sites. The manganese-based system design reduces the preparation cost, and the high-entropy doping approach further decreases the content of crystalline water in the structure. Benefiting from the synergistic effects of the multiple component elements, HE-HCF demonstrates a capacity retention rate of 72.7% at 0.1 A g−1. Moreover, it even maintains 85.3% of its initial capacity after 1000 cycles at 1 A g−1. Electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT) analyses further confirm that HE-HCF exhibits low charge transfer resistance and a small reaction activation energy.