Hollow opening nanoflowers MoS2-CuS-EG cathodes for high-performance hybrid Mg/Li-ion batteries

Abstract Hybrid Mg/Li-ion Batteries (MLIBs) combine both the advantages of fast alkali metal ions intercalation cathode and dendrite-free Mg anode that exhibits satisfactory electrochemical performance. However, achieving superior comprehensive battery performance is still a main challenge for MLIBs. Novel hollow opening nanoflower MoS2-CuS-EG (HONF-MoS2-CuS-EG) cathode with unique structure as MLIBs cathode was firstly fabricated via a facile hydrothermal method and superior comprehensive electrochemical performances are presented. Constructed by increased interlayer distance MoS2, metallic-like conductivity CuS and superior electrical conductivity EG, high discharge capacity and superior rate performance are demonstrated by HONF-MoS2-CuS-EG electrode. The volume expansion/contraction during charge-discharge cycles can be effectively buffered by EG and superior cycle stability. The discharge capacity at 10th cycle is as high as 240.6 mAh·g−1, which increases over the 1st cycle by 8.6% at 50 mA·g−1. The discharge capacities at 200 and 1000 mA·g−1 are 201.4 and 117.5 mAh·g−1. The capacity retention rates after 100 cycles (172.4 mAh·g−1) and 200 cycles (73.5 mAh·g−1) for HONF-MoS2-CuS-EG electrode at 50 mA·g−1 are 47.43% and 22.22%, which are much higher than those of hollow close nanoflower MoS2 (HCNF-MoS2) cathode (2.81% and 1.95%). As high as 262.5 mAh·g−1 discharge capacity with 91.6% capacity retention of HONF-MoS2-CuS-EG at 500 mA·g−1 and 150 cycles is presented, indicating that increasing current density is favor to cycle performance of HONF-MoS2-CuS-EG cathode. The electrochemical mechanism of HONF-MoS2-CuS-EG electrode in MLIBs is also elaborated. This work provides a practical approach to construct advanced MoS2-based cathode materials for MLIBs.