Catalyst engineering for lithium ion batteries: The catalytic role of Ge in enhancing the electrochemical performance of SnO₂(GeO₂)_0.13/G anodes

The catalytic role of germanium (Ge) was investigated to improve the electrochemical performance of tin dioxide grown on graphene (SnO₂/G) nanocomposites as an anode material of lithium ion batteries (LIBs). Germanium dioxide (GeO₂) and SnO₂ nanoparticles (<10 nm) were uniformly anchored on the graphene sheets via a simple single-step hydrothermal method. The synthesized SnO₂(GeO₂)_0.13/G nanocomposites can deliver a capacity of 1200 mA h g^-1 at a current density of 100 mA g^-1, which is much higher than the traditional theoretical specific capacity of such nanocomposites (∼702 mA h g^-1). More importantly, the SnO₂(GeO₂)_0.13/G nanocomposites exhibited an improved rate, large current capability (885 mA h g^-1 at a discharge current of 2000 mA g^-1) and excellent long cycling stability (almost 100% retention after 600 cycles). The enhanced electrochemical performance was attributed to the catalytic effect of Ge, which enabled the reversible reaction of metals (Sn and Ge) to metals oxide (SnO₂ and GeO₂) during the charge/discharge processes. Our demonstrated approach towards nanocomposite catalyst engineering opens new avenues for next-generation high-performance rechargeable Li-ion batteries anode materials.