Highly Reversible Lithium-Ion Battery with Excellent Rate Performance and Cycle Stability Based on a Ti₃C₂/CoS₂...

Transition metal sulfide (TMS) CoS₂ is considered an ideal anode material for new-generation lithium-ion batteries (LIBs) because of its high specific capacity, high electrochemical activity, and low cost. However, CoS₂ is prone to volume expansion and structural collapse when it participates in the internal conversion reaction of the battery, which limits its practical application. After analyzing the failure mechanism of CoS₂ as the anode material of LIBs, the concept of nanoengineered materials is introduced here. CoS₂ particles are nanosized and stabilized by constructing a composite structure on an alkali-treated two-dimensional Ti₃C₂ Mxene conductive network. Both experiments and theoretical calculations show that special Ti-O-Co bonds are formed at the interface of the Ti₃C₂/CoS₂ composite through oxygen-containing functional groups. Ti-O-Co bonding with adjustable electronic characteristics can effectively promote the utilization rate of anode materials, electronic conductivity, and ionic diffusivity and thus enhance the redox reaction kinetics of the device. When the Ti₃C₂/CoS₂ composite is used as the anode material for LIBs, it still provides a high specific capacity of 405.8 mAh g^-1 after 100 cycles at 0.1 A g^-1. After running for 1000 cycles at a high current of 1 A g^-1, the capacity retention is still close to 100%. Also, high cycle stability under the condition of highly active material loading (10.58 mg cm^-2) and low electrolyte/active material ratio (10 μL mg^-1) is achieved. This work provides a new idea for the development of commercial LIBs as anode materials.