A Micro-Cracked Conductive Layer Made of Multiwalled Carbon Nanotubes for Lithium-Ion Batteries

A conductive layer, made of multiwalled carbon nanotubes (MWCNTs), with micro-cracks and a micro/nanoporous structure is fabricated between an active material layer (AML) and a current collector. The coating thickness of the MWCNT-based conductive layer (MCL) varies in the range of 25-100m. Electrochemical tests of half-cells demonstrate that both the mesocarbon-microbeads (MCMB) anode and the LiCoO2 cathode with a micro-cracked MCL show higher capacity, lower impedance, and less capacity fading than the pristine and non-cracked electrodes. These improvements are caused by the enhancement of adhesion strength and the buffer effect of the micro-cracked MCL. With a change of the coating thickness, the size and number of micro-cracks on the MCL varies to accommodate the active material with different particle sizes. The electrodes with a micro-cracked MCL with a coating thickness of 50 and 75 mu m are suitable for MCMB and LiCoO2 with a particle size of 10-20 mu m.