CNTs@C@Cu2‐xSe Hybrid Materials: An Advanced Electrode for High Performance Lithium Batteries and Supercapacitors

Abstract In this work, one dimensional CNTs@C anchored with Cu 2‐x Se nanospheres have been prepared by a facile solvothermal method. The parameters affected the morphology of the sample are investigated. When evaluated as anode for Li ion batteries, the obtained CNTs@C@Cu 2‐x Se electrode delivers enhanced electrochemical performance with high reversible capacity, better cycle stability and rate capability. After 100 th cycle, a discharge capacity of 399 mAh g −1 can be achieved at 0.1 A g −1 . Even at high rate of 2 A g −1 , the electrode can still keep a capacity of 198 mAh g −1 after 50 cycles. In addition, the obtained CNTs@C@Cu 2‐x Se shows typical faradaic redox properties and exhibits excellent specific capacity (302.7 g −1 at 1 A g −1 ) and prominent cycling stability (86.9 % capacity retention after 2000 cycles at 2 A g −1 ). The enhanced electrochemical performance can be attributed to the unique structure. The Cu 2‐x Se nanospheres consist of numerous nanocrystalline, which increases the contact area between Cu 2‐x Se and electrolyte, reduces the pave length as well as accommodates volume change during cycling. The amorphous carbon layer with numerous carboxyl and hydroxyl groups strengthens the adhesion between the Cu 2‐x Se and the CNTs. And the CNTs can enhance the conductivity of Cu 2‐x Se and alleviate the mechanical stress and strain of the electrode during charge and discharge process.