Delaying-volume-change CaCo2O4/rGO as anode for high performance lithium-ion and sodium-ion batteries

Abstract

CaCo2O4/rGO was prepared by sol-gel strategy and mechanical ball milling method. The Rietveld refinement results demonstrate that a single-phase structure with a monoclinic symmetry can be obtained. When utilized as the anode for lithium-ion batteries, it exhibits excellent rate performance and electrochemical stability due to the significantly decreasing the particle size as well as the forming a conductive rGO network in the composite after ball milling. A reversible stable specific capacity of 778 mA h g−l is attained at a current density of 200 mA h g−l after 100 cycles between 0.01-3 V (vs. Li/Li+). The long cycling capacity of 608.5 mA h g−l can still be remained following 300 cycles at 1 A g−l. The evolution of CaCo2O4 structural and phases during electrochemical cycling processes was thoroughly investigated for the first time using in-situ analytical techniques to elucidate the Li+ storage mechanism. Here, the electrochemical performance of CaCo2O4/rGO as the anode material for sodium-ion batteries is also reported on the first occasion, and a reversible specific capacity of 400 mA h g−l can be achieved at a current density of 20 mA h g−l between 0.01-3 V (vs. Na/Na+) with the good electrochemical performance.