Synthesis and electrochemical properties of Zn2Ti3O8/g-C3N4 composites as anode materials for Li-ion batteries

Abstract

Zn₂Ti₃O₈/g-C₃N₄ (0, 1, 3 and 8 wt%) composites were prepared via a simple solvothermal method, and their physical and electrochemical properties were systematically analyzed. SEM and HRTEM results show that the Zn₂Ti₃O₈/g-C₃N₄ spherical structures with width sizes of about 500–700 nm are plump and uniform. Moreover, g-C₃N₄ with a large specific surface area can effectively buffer the deformation of Zn₂Ti₃O₈ and reduce the resistance of Zn₂Ti₃O₈ charge transfer and Li⁺ diffusion, thus improving the conductivity of Zn₂Ti₃O₈. The results reveal that Zn₂Ti₃O₈/g-C₃N₄ (3 wt%) had the most outstanding electrochemical performance of all samples. It can deliver discharge (charge) capacities of 444.6 (387.9), 284.5 (280.8), 197.5 (199.9), 149.9 (149.3), 119.2 (118.7) and 81.4 (81) mA h g⁻¹ cycled at 50, 100, 300, 600, 900, and 1500 mA g⁻¹, respectively. At the same current densities, pure Zn₂Ti₃O₈ only provides discharge (charge) capacities of 325.4 (283.5), 223.7 (219.5), 142.9 (141.8), 95.4(94.8), 69.4 (69.4) and 38.3 (39.3) mA h g⁻¹. The results verify that Zn₂Ti₃O₈/g-C₃N₄ materials are expected to be remarkable anode materials for Li-ion batteries.