Chemical binding and conformal coating of sub-10 nm SnNi alloy layer on nanostructured carbon matrices enabling enhanced lithium storage

Alloy material is one of the most promising high-capacity anodic categories in Li-ion batteries, but suffers from huge volume expansion for practical applications. Hybridizing alloys with nanostructured carbon matrices is desirable to improve the overall electrochemical performances, however, alloys always distribute sparsely on nanostructured carbon matrices by physical connections, and easily detach from carbon matrices and aggregate to big congeries upon cycling. Here, we develop a facile and general hyrdogel-reduction approach for chemically binding and conformally coating alloys on nanostructured carbon matrices. As a typical illustration, carbon black (CB) is first immobilized within cyano-bridged Sn-Ni coordination polymer gel (Sn-Ni cyanogel), and after reduction, sub-10 nm Sn-Ni alloy layer is conformally coated on CB surface via Sn-O-C bonds, yielding the final CB@Sn-Ni hybrid framework. The sub-10 nm alloy layer and conformal coating nanostructure together with strong chemical bonding enable the CB@"Sn-Ni hybrid anode to exhibit long cycle life (400 mA h g(-1) after 350 cycles at 0.2 A g(-1)) and high rate performance (294 and 190 mA h g(-1) at 5 and 10 A g(-1), respectively). This work provides an alternative insight into conformally coating and chemical combining electrode materials with nanostructured carbon matrices for boosting electrochemical properties.