Origin of enhanced stability of SiO anode via using carbon nanotubes

Abstract

High-capacity SiO (SO)-based alloys are among the most promising anodes for next-generation lithium-ion batteries (LIBs). Challenges of SO-based anodes, including sluggish kinetics and poor stability, have been effectively mitigated by using carbon nanotubes (CNTs) as conductive additives. However, the underlying mechanism, apart from kinetics, remains elusive. Herein, we find that CNTs can help to maintain complete conductive networks of electrodes after cycling, ensuring uniform lithiation reaction. The alleviated local extra-huge volume expansion of SO will further suppress continuous solid-state interphase growth, active material delamination from the current collector, and even lithium plating. Accordingly, pure SO anode with CNTs (SO-CNTs) can cycle stably with the capacity retention of 96.2% over 200 cycles at 0.5 C (1 C = 1600 mA g−1). The function of CNTs is further proved in practical SO/graphite (SO650-CNTs, 1 C = 650 mA g−1) anode with a high capacity retention of 80.6% over 400 cycles at 1 C. This work provides a new perspective on the functional mechanism of conductive additives, and will accelerate the commercialization of alloy anodes in the battery industry.