Zn2GeO4 nanorods grown on carbon cloth as high performance flexible lithium-ion battery anodes

Abstract

To improve the electrical conductivity and cycling stability of germanium compounds as anode materials for lithium ion batteries (LIBs), Zn₂GeO₄ nanorods grown on carbon cloth (Zn₂GeO₄/CC) were designed and fabricated by a simple hydrothermal process combined with a post-annealing treatment. The Zn₂GeO₄/CC composites possess hierarchical porosity and a network structure. Serving as free-standing and binder-free anodes for LIBs, they exhibit high specific capacity and excellent reversibility. A discharge capacity as high as 1851.9 mA h g⁻¹ is attained at a current density of 200 mA g⁻¹, and the Zn₂GeO₄/CC electrode still maintains a high reversible capacity of 1302.3 mA h g⁻¹ after 200 cycles. Even at a high specific current of 2000 mA g⁻¹, it still retains a capacity of 847.5 mA h g⁻¹. The superior electrochemical performance of the Zn₂GeO₄/CC composites is attributed to the synergistic effects of the hierarchical porosity, Zn₂GeO₄ nanorods, and 3D carbon cloth network structure, which can effectively accommodate the huge volume change of the Zn₂GeO₄ nanorods during cycling and maintain perfect electrical conductivity throughout the electrode. Moreover, the excellent mechanical flexibility of the Zn₂GeO₄/CC composites makes the material a promising candidate for self-supported and flexible electrodes for LIBs.