Realizing Superior Prussian Blue Positive Electrode for Potassium Storage via Ultrathin Nanosheet Assembly

Prussian blue analogues have attracted growing attention as the positive electrode materials in rechargeable potassium-ion batteries (KIBs) due to the intrinsic open frameworks and high theoretical capacities. However, the bulk synthesized Prussian blue which is accompanied by aggregation inevitably results in the limited K + ion mobility and suppressed potassium storage performance. In this work, ultrathin nanosheet-assembled hierarchical Prussian blue materials (K 1.4 Fe 4 [Fe(CN) 6 ] 3 ) are synthesized via a facile dissolution-recrystallization strategy. On the strength of this architecture, the positive electrode displays both high rate (71 and 24.9 mAh g –1 at 50 and 600 mA g –1 ) and long life-span properties (75.2% of the primal capacity retained after 100 cycles) for potassium storage. The enhanced diffusion kinetics and structural stability are further demonstrated through the galvanostatic intermittent titration technique analysis and ex-situ X-ray diffraction. Our work provides a new nanostructuring strategy for improving the potassium storage in intercalation electrodes.