Metal nanodots anchored on carbon nanotubes prepared by a facile solid-state redox strategy for superior lithium storage

Abstract

Alloying-based electrode materials (e.g. Si, Sn, Sb, Bi, etc.) are the promising anode candidates for next-generation lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) owing to their high specific capacities, but they suffer from huge volume changes upon lithium/sodium insertion/extraction processes. On the other hand, such alloying anodes usually require a complicated and high energy-consumption synthesis process (e.g. Si anode by a magnesiothermic reduction at over [Formula: see text]C, Sn, Sb and Bi anodes by a high-temperature carbothermic reduction at 600–[Formula: see text]C), thus limiting their practical application for replacing low-cost graphite. In this work, we develop a straightforward solid-state strategy for a general synthesis of metal nanodots (Sn, Sb and Bi) supported on carbon nanotubes (CNTs) by using the reduction potential differences of metal salts and NaBH4 as the reaction power at room temperature. Owing to the very mild reaction, the resulted active component is small enough (2–5[Formula: see text]nm) with diffusion-less and nucleation-less barriers upon alloying/dealloying reaction, thus enabling high electrode stability and high capacity retention. Taking Sn anode as an example, the obtained Sn/CNTs deliver a high reversible capacity of 415[Formula: see text]mAh g[Formula: see text] at 0.5[Formula: see text]A g[Formula: see text] after 1000 cycles without obvious capacity decay. Such findings indicate that the proposed solid-state synthetic method could offer a great potential for realizing large-scale and economic applications of energy storage materials.