Cu 12 Sb 4 S 13 Quantum Dots/Few‐Layered Ti 3 C 2 Nanosheets with Enhanced K + Diffusion Dynamics for Efficient Potassium Ion Storage

Despite the high theoretical specific capacity of transition-metal disulfides anode for potassium-ion batteries (PIBs), their development has been greatly hindered by dramatic capacity fading and poor cycle life. Herein, the synthesis of the new composite of Cu12Sb4S13 quantum dots/few-layered Ti3C2 nanosheets (CAS-Ti3C2) as advanced anode for boosting the K ion storage is reported. It is found that as-made CAS-Ti3C2 show a strong synergistic effect between quantum dots and Ti3C2 nanosheets mainly caused by the formation of the Ti–S bond, which can not only shorten the diffusion path of K+ but also accommodate the serious volumetric variation during the discharge/charge process. As expected, this specially designed CAS-Ti3C2 anode exhibits a superior reversible specific capacity of 496.7 mAh g−1 at 100 mA g−1 after 200 cycles and 175.6 mAh g−1 at a high current density of 1.0 A g−1 even over 1800 cycles, preceding most of the reported transition-metal disulfides quantum dots-based anodes for PIBs. These comprehensive studies reveal that the excellent electrochemical property is attributed to the fast K+ diffusion kinetics and unique transformation and restorage mechanism between K+ with CAS-Ti3C2 anode.