Single-walled carbon nanotube as conductive additive for SiO/C composite electrodes in pouch-type lithium-ion batteries

Abstract

SiO/C is believed to be one of the most promising anode material for lithium-ion batteries due to the low operation potential and superior theoretical capacity. However, the substantial volume change during cycling process limits its further practical application. Herein, we report an affordable and highly effective approach to enhancing the electrochemical performance by adding a small amount of single-walled carbon nanotubes (SWCNT) as conductive additive for SiO/C anodes. An efficient liquid-phase mixing approach is employed to evenly disperse the SWCNT into silicon oxide/graphite composite anode for lithium-ion batteries (LIBs). The electrochemical capability is carried out using pouch full cells with commercial electrode areal loading and mass loading. The addition of SWCNT (0.5%) reduces film resistance and direct current resistance (DCR) for charging. The lithium-ion diffusion coefficient is 6.32 × 10−15 cm2 s−1 for SWCNT-added sample, which is an order of magnitude higher than that of the sample without SWCNT (2.33 × 10−16 cm2 s−1). Furthermore, the battery assembled by the SWCNT-adding electrode shows better rate performance and cycle stability. The charge efficiency improves 1.25 times at 4 C charging, which enables fast charging for LIBs. The cycling results show that SWCNT-adding electrode displays capacity retention of 90.30% after 600 cycles at 1 C. Furthermore, the loading of SiO/C electrode increases from 93.4 to 95.4 wt%, which is beneficial for improvement of energy density. It is worth noting that it suggests a well-designed recipe for the practical application of SWCNT for LIBs.