Abstract

Prussian blue (PB) has attracted considerable attention as a cathode material for sodium-ion batteries owing to its low cost and fast Na+ diffusion kinetics. However, conventional aqueous synthesis often involves rapid nucleation and non-uniform crystal growth, resulting in residual crystal water and lattice defects that compromise structural stability and electrochemical performance. Various strategies, including non-aqueous and solvothermal approaches, have been explored to mitigate these issues, yet precise control over defect formation remains challenging because of complex processing and residual water. Herein, a purely non-aqueous glycerol-based synthesis strategy incorporating NaCl is proposed, without involving solvothermal processes or aqueous/organic solvent mixtures, to fundamentally address these intrinsic limitations. The high viscosity of glycerol moderates reaction kinetics, while the NaCl-regulated ionic environment enables controlled nucleation and growth, yielding uniformly sized PB nanoparticles with diameters of 200–300 nm. As a result, sodium-rich phase with enhanced crystallinity is obtained compared to PB synthesized via conventional non-aqueous routes. The as-synthesized PB exhibits effectively suppressed crystal water-induced side reactions and mitigated particle cracking during electrochemical cycling, leading to stable voltage profiles and improved long-term cycling stability. Notably, the material retains approximately 79.6% of its initial capacity after 10,000 cycles at a high rate of 10C, demonstrating substantially enhanced durability under the harsh conditions. This work demonstrates that the structural instability of PB can be fundamentally controlled at the synthesis stage through a simple non-aqueous strategy, thereby offering new opportunities for the design of long-life sodium-ion battery cathodes.