Carbon materials toward efficient potassium storage: Rational design,performance evaluation and potassium storage mechanism

Potassium-ion batteries(PIBs) are potential “Beyond Li-ion Batteries” candidates for their resource advantage and low standard electrode potential. To date, the research on PIBs is in its early stages, the most urgent task is to develop high-performance electrode materials and reveal their potassium storage mechanism. For PIBs anode materials, carbon with tunable microstructure, excellent electrochemical activity, nontoxicity and low price is considered as one of the most promising anode materials for commercialization. Although some breakthrough works have emerged, the overall electrochemical performance of the reported carbon anode is still far away from practical application. Herein, we carry out a comprehensive overview of PIBs carbon anode in terms of three aspects of rational design of structure, performance evaluation criteria and characterization of potassium storage mechanism. First, the regulation mechanism of key structural features of carbon anode on its potassium storage performance and the representative structural regulation strategies are introduced. Then, in view of the undefined performance evaluation criteria of PIBs carbon anode, a reference principle for evaluating the potassium storage performance of carbon anode is proposed. Finally, the advanced characterization techniques for the potassium storage mechanism of carbon anode are summarize. This review aims to provide guidance for the development of practical PIBs anode.