Template-Free Synthesis of Hollow-Structured Co₃O₄ Nanoparticles as High-Performance Anodes for Lithium-Ion Batteries

We have developed a template-free procedure to synthesize Co₃O₄ hollow-structured nanoparticles on a Vulcan XC-72 carbon support. The material was synthesized <i>via</i> an impregnation–reduction method followed by air oxidation. In contrast to spherical particles, the hollow-structured Co₃O₄ nanoparticles exhibited excellent lithium storage capacity, rate capability, and cycling stability when used as the anode material in lithium-ion batteries. Electrochemical testing showed that the hollow-structured Co₃O₄ particles delivered a stable reversible capacity of about 880 mAh/g (near the theoretical capacity of 890 mAh/g) at a current density of 50 mA/g after 50 cycles. The superior electrochemical performance is attributed to its unique hollow structure, which combines nano- and microscale properties that facilitate electron transfer and enhance structural robustness