Bicontinuous hierarchical Na7V4(P2O7)4(PO4)/C nanorod–graphene composite with enhanced fast sodium and lithium ions intercalation chemistry

摘要: Mixed polyanion materials with a 3D framework for battery electrodes have been attracting significant attention recently in view of the requirements to further improve energy storage and power densities. Herein, we present design hierarchical Na7V4(P2O7)4(PO4)/C nanorod–graphene composite as sodium- lithium-storage cathode materials. The structure is composed 1D rectangular nanorod, which coated by situ residual carbon wrapped reduced graphene-oxide sheet. open network graphene surface coating nanorod provide bicontinuous electron ion pathways, providing three-dimensional conductive efficient transfer. flexible electrode built from free binder or additive exhibits improved conductivity higher sodium/lithium migration coefficients than pristine nanorod. It approaches initial reversible electrochemical capacities 91.4 91.8 mA h g−1 high discharge potentials over 3.8 V (vs. Na/Na+ Li/Li+) good cycling properties capacity retentions 95% 83% after 200 cycles at 1 C rate sodium lithium intercalation systems, respectively. Even 10 C, it still delivers 87.4% (for sodium) 78.2% lithium) stability. Taking into consideration compatibilities both ions their superior characteristics, considered be promising high-rate capability material advanced applications.