In situexsolution of Ag from AgBiS2nanocrystal anode boosting high-performance potassium-ion batteries

The irreversible formation of a solid electrolyte interface (SEI) film on semimetal/semiconductors impedes the electrochemical migration of K(+)in potassium-ion batteries due to the inevitable volume expansion of the anode materials. Herein, we report thein situexsolution of Ag in metastable nanostructured AgBiS(2)to spontaneously assist cycling for K(+)intercalation. Thein situXRD and ex situ HRTEM techniques revealed unique phase transitions during the uptake of K(+)on account of the mixed ion storage mechanism. During the initial reduction process, AgBiS(2)underwent K+/AgBiS(2)displacement, K+/BiS(2)conversion, and K+/Bi alloying reaction. The exsolution of Ag was electrochemically reduced in the process of K(+)insertion and remained as an intermediate charge transmitter to sustain a high reversible capacity of 420 mA h g(-1)at 0.5 A g(-1), superior rate performance of 210 mA h g(-1)at 5 A g(-1)and long-term (over 300) cycle stability. This work presents a strategy to resolve the issues of single-element anodes in metal-ion batteries.