Targeted Construction of Amorphous MoSx with an Inherent Chain Molecular Structure for Improved Pseudocapacitive Lithium‐Ion Response

Abstract Owing to low ion/electron conductivity and large volume change, transitional metal dichalcogenides (TMDs) suffer from inferior cycle stability and rate capability when used as the anode of lithium‐ion batteries (LIBs). To overcome these disadvantages, amorphous molybdenum sulfide (MoS x ) nanospheres were prepared and coated with an ultrathin carbon layer through a simple one‐pot reaction. Combining X‐ray photoelectron spectroscopy (XPS) with theoretical calculations, MoS x was confirmed as having a special chain molecular structure with two forms of S bonding (S 2− and S 2 2− ), the optimal adsorption sites of Li + were located at S 2 2− . As a result, the MoS x electrode exhibits superior cycle and rate capacities compared with crystalline 2H‐MoS 2 (e.g., delivering a high capacity of 612.4 mAh g −1 after 500 cycles at 1 A g −1 ). This is mainly attributed to more exposed active S 2 2− sites for Li storage, more Li + transfer pathways for improved ion conductivity, and suppressed electrode structure pulverization of MoS x derived from the inherent chain‐like molecular structure. Quantitative charge storage analysis further demonstrates the improved pseudocapacitive contribution of amorphous MoS x induced by fast reaction kinetics. Moreover, the morphology contrast after cycling demonstrates the dispersion of active materials is more uniform for MoS x than 2H‐MoS 2 , suggesting the MoS x can well accommodate the volume stress of the electrode during discharging. Through regulating the molecular structure, this work provides an effective targeted strategy to overcome the intrinsic issues of TMDs for high‐performance LIBs.