Regulating the Structure and Kinetic Properties of Prussian White Cathode With Atmosphere Protection for Sodium-Ion Batteries.

Manganese hexacyanoferrate (MnHCF), also known as Prussian white cathode material, has become a popular choice for sodium-ion batteries due to its high output voltage, low cost, and high theoretical specific capacity. However, MnHCF synthesized via conventional methods exhibits a cubic phase, presenting issues such as CN vacancies, crystalline water, poor conductivity, and complex phase transitions during charge-discharge cycles. These factors lead to low capacity utilization and poor cycle life, limiting its application in sodium-ion batteries. The performance of Prussian white cathode material is closely related to its structure. In this study, MnHCF with monoclinic phase characteristics was synthesized by introducing nitrogen as the reaction atmosphere. After 200 cycles at 5C, its capacity retention rate was 75%, showing more excellent cycle performance and rate performance compared with the cubic phase. Additionally, this work investigates structural changes during moderate discharge cycles. Crucially, in situ EIS and cyclic voltammetry at varying scan rates characterize the evolving kinetic processes throughout charge-discharge cycles. This study presents an effective synthesis strategy, which is helpful for the design and optimization of Prussian blue analog sodium-ion batteries.