Octahedral Co3O4 particles threaded by carbon nanotube arrays as integrated structure anodes for lithium ion batteries

Octahedral Co3O4 particles threaded by ultra-long multi-walled carbon nanotube (MWCNT) arrays were prepared by a hydrothermal process and subsequent calcination. The Co3O4 octahedron with the (111) facets attaches to MWCNTs uniformly and closely. The composite can be used as an integrated anode for lithium ion batteries (LIBs) without any other additives (such as conductive additives and polymer binder), which exhibits a high reversible capacity of 725 mA h g−1 at a current density of 100 mA g−1, and excellent cyclic stability without capacity degradation over 100 cycles at a current density of 500 mA g−1. The high performance can be attributed to the unique structure: (i) the ultra-long MWCNT array facilitates fast electron transfer; (ii) the tight adhesion between Co3O4 and MWCNTs prevents particle drifting and agglomeration; (iii) the free space between MWCNTs promotes fast ion transport and alleviates the large volume variation during discharge–charge process. This work demonstrates the great potential of MWCNT arrays as substrate and provides insights for the design and direct use of MWCNT array-based materials in LIBs, which will be helpful for future development of high-performance electrode materials.