Sandwich-structured cathodes with cross-stacked carbon nanotube films as conductive layers for high-performance lithium-ion batteries

Abstract

A simple and feasible strategy of using cross-stacked super-aligned carbon nanotube (SACNT) films as conductive layers to prepare sandwich-structured LiCoO₂ cathodes for high-performance lithium-ion batteries (LIBs) is reported. Owing to the super-aligned feature, the SACNTs are fully dispersed and form a homogeneous and efficient conductive network in the electrodes. Meanwhile, the sandwiched electrode structure, consisting of a repeating and alternating stack of LiCoO₂ layers and SACNT films, ensures that each layer of active materials can adhere to the SACNT conductive layers, realizing sufficient electron transfer throughout the electrodes regardless of the thickness of the electrodes. With the introduction of three separate SACNT conductive layers, significant improvements on the conductivity as well as the cell performance are achieved. The sandwich-structured LiCoO₂–2 wt% Super P–SACNT cathodes possess an impressive rate capability (109.6 mA h g⁻¹ at 10C and 1668% improvement compared with that without SACNT films), showing the best rate performances reported so far for commercial micro-sized LiCoO₂ particles. The easy fabrication procedure, compatible method for commercialization, low cost, and outstanding electrochemical performances of the sandwich-structured electrode demonstrate its great potential for the large-scale production of high-performance electrodes for LIBs.