In Situ Synthesis and Unprecedented Electrochemical Performance of Double Carbon Coated Cross-Linked Co₃O₄

Improving the structural stability and the electron/ion diffusion rate across whole electrode particles is crucial for transition metal oxides as next-generation anodic materials in lithium-ion batteries. Herein, we report a novel structure of double carbon-coated Co3O4 cross-linked composite, where the Co3O4 nanoparticle is in situ covered by nitrogen-doped carbon and further connected by carbon nanotubes (Co3O4 NP@NC@CNTs). This double carbon-coated Co3O4 NP@NC@CNTs framework not only endows a porous structure that can effectively accommodate the volume changes of Co3O4, but also provides multidimensional pathways for electronic/ionic diffusion in and among the Co3O4 NPs. Electrochemical kinetics investigation reveals a decreased energy barrier for electron/ion transport in the Co3O4 NP@NC@CNTs, compared with the single carbon-coated Co3O4 NP@NC. As expected, the Co3O4 NP@NC@CNT electrode exhibits unprecedented lithium storage performance, with a high reversible capacity of 1017 mA h g–1 after 500 cycles at 1 A g–1, and a very good capacity retention of 75%, even after 5000 cycles at 15 A g–1. The lithiation/delithiation process of Co3O4 NP@NC@CNTs is dominated by the pseudocapacitive behavior, resulting in excellent rate performance and durable cycle stability.