Pseudo-capacitance reinforced modified graphite for fast-charging potassium-ion batteries

Abstract

As emerging energy storage systems, potassium-ion batteries (PIBs) are suitable for grid-scale energy storage application due to the abundant potassium resources and low cost. It is crucial to achieve fast-charging PIBs. However, as the most promising anode candidate, graphite still faces setbacks in achieving fast charging due to poor kinetic issue. Herein, modified graphite (MG) is synthesized to realize the fast potassium ion storage. Benefiting from the enlarged graphitic space combined with unique porous microstructure, MG exhibits outstanding electrochemical performance. The optimized MG anode delivers a specific capacity of 115 mAh g−1 at 4 A g−1 and excellent cycling stability of 1500 cycles at 1 A g−1. Moreover, the full cell assembled with MG anode and Prussian Blue (PB) cathode exhibits a capacity retention of 75% after 20000 cycles at the current density of 1 A g−1. The excellent electrochemical performance is further demonstrated to be associated with dominant pseudo-capacitance behavior, i.e. surface or near-surface reversible redox reactions, which are less affected by solid electrolyte interface (SEI) than intercalation reactions. Our work proposes a strategy to optimize graphitic anode materials by regulating the microstructure and may provide insight into the synthesis of high rate carbon-based anode materials for PIBs.