Regulating Lattice-Water-Adsorbed Ions to Optimize Intercalation Potential in 3D Prussian Blue Based Multi-Ion Microbattery

Miniaturized energy storage device (MESD) is the core module in microscale electronic equipment, yet its electrochemical performance is far away from the actual requirements. The extensive research efforts have improved the performance of MESD via the fabrication techniques and material construction, while ignoring the expansion of optimization strategy in the combination of energy storage mechanism. Herein, the Prussian blue/Zn microbattery is reported with the regulation of lattice-water-adsorbed intercalated ion. The optimal charge transport of cathode is achieved via the optimization of 3D structure of microelectrode to maximize the electrochemical performance. Also, lattice-water-adsorbed ion storage mechanism is further investigated to guide the design of differential energy storage for cathode and anode. The Cu₃(Fe(CN)₆)₂/Zn microbattery, with K⁺ inter/deintercalation in the cathode and Zn²⁺ deplating/plating in the anode, displays high capacity (0.281 mAh cm⁻² at 2.5 mA cm⁻²), rate performance (0.181 mAh cm⁻² at 25 mA cm⁻²), and cycling stability (77.6% capacity retention after 1500 cycles) enhanced by Cu²⁺ in the electrolyte. This highly efficient combination of fabrication process, active material, and multi-ion storage for microelectrode shows a high tolerance for optimization strategies, expanding the compatibility of optimization path for high-performance MESD.