Lowering the voltage-hysteresis of CuS anode for Li-ion batteries via constructing heterostructure

Conversion-reaction anode materials always deliver high capacities when used for Li-ion batteries (LIBs). However, the large voltage-hysteresis between the discharge and charge potentials slide down the round-trip efficiency of the electrodes, which restricts their further application on commercial LIBs. Herein, an assumption that lowering the voltage-hysteresis by constructing heterostructure is proposed and further verified by CuS based electrode. As a proof of concept, CuS/MnS heterostructure nanoparticles confined by carbon layers are designed and further crosslinked into a 3D network, constructing CuS/MnS-C heterostructure nanofibers (HNFs). The as-formed heterointerfaces facilitate the charge separation and transfer, and further improve the kinetics. Meanwhile, the confinement and conductive network of the carbon nanofibers improve the structural stability and conductivity of the hybrid electrode. As a result, the voltage-hysteresis values of the CuS anode are lowered to 0.30 and 0.35 V in the well-designed CuS/MnS-C HNFs electrode, much smaller than the original values (0.82 and 0.70 V) in the CuS-C NFs electrode. Moreover, the CuS/MnS-C HNFs electrode exhibits the best excellent rate capability among their counterpart electrodes (493.5 mAh g(-1) at 2.0 A g(-1) with the coulombic efficiency of about 100%). This work would shed light on the development of practical conversion-reaction anode materials with low voltage-hysteresis.