Optimization of VOSO4@C cathode materials with CNT and GO for lithium-ion batteries

Abstract

VOSO 4 is a promising cathode material for lithium-ion batteries owing to its polyanionic structure and the polyvalency of vanadium. In this study, carbon nanotubes (CNTs) and graphene oxide (GO) were adopted for modifying the microstructure and improving the overall performance of VOSO 4 . Before the chemical synthesis of VOSO 4 , the CNTs were firstly combined with precursor and CNT-VOSO 4 @C was formed via a one-step chemical synthesis. The results showed that CNTs could improve the charge–discharge performance of the VOSO 4 @C. The initial discharge specific capacity of CNT-VOSO 4 @C was up to 151.6 mAh·g −1 at 0.05 C, and even at 1 C the capacity could reach 66.06 mAh·g −1 . The discharge–capacity retention rate is 100% after a long circulation. Secondly, CNTs and GO were composited with the synthesized VOSO 4 @C and the obtained composites VOSO 4 @C-CNT and VOSO 4 @C-GO exhibited good electrochemical properties with initial discharge specific capacities of 135.7 and 141.8 mAh·g −1 at 0.05 C, respectively. This may be attributed to the high specific surface areas and conductivities of CNTs and GO. When grinding the composites, CNTs and GO are uniformly distributed among the particles, forming bridges between the particles, that can increase the electrical conductivity between the particles and reduce the volume expansion of electrode materials. CNT-VOSO 4 @C exhibits the best modification effect. This study proposes a feasible approach for applying VOSO 4 in lithium-ion batteries, particularly under weak currents. • CNT and GO act as bridges between the VOSO 4 @C particles. • CNT-VOSO 4 @C has the best initial discharge capacity and capacity retention rate. • This work provides a feasible approach for applying VOSO 4 in lithium-ion battery, especially at weak currents.