MoS2 as a long-life host material for potassium ion intercalation

Electrochemical potassium ion intercalation into two-dimensional layered MoS2 was studied for the first time for potential applications in the anode in potassium-based batteries.X-ray diffraction analysis indicated that an intercalated potassium compound,hexagonal K0.4MoS2,formed during the intercalation process.Despite the size of K+,MoS2 was a long-life host for repetitive potassium ion intercalation and de-intercalation with a capacity retention of 97.5％ after 200 cycles.The diffusion coefficient of the K+ ions in KxMoS2 was calculated based on the Randles-Sevcik equation.A higher K+ intercalation ratio not only encountered a much slower K+ diffusion rate in MoS2,but also induced MoS2 reduction.This study shows that metal dichalcogenides are promising potassium anode materials for emerging K-ion,K-O2,and K-S batteries.