High-Rate SiO Lithium-Ion Battery Anode Enabled by Rationally Interfacial Hybrid Encapsulation Engineering

The development of a high-rate SiO lithium-ion battery anode is seriously limited by its low intrinsic conductivity, sluggish interfacial charge transfer (ICT), and unstable dynamic interface. To tackle the above issues, interfacial encapsulation engineering for effectively regulating the interfacial reaction and thus realizing a stable solid electrolyte interphase is significantly important. Hybrid coating, which aims to enhance the coupled e-/Li+ transport via the employment of dual layers, has emerged as a promising strategy. Herein, we construct a hybrid MXene-graphene oxide (GO) coating layer on the SiO microparticles. In the design, Ti3C2Tx MXene acts as a "bridge", which forms a close covalent connection with SiO and GO through Ti-O-Si and Ti-O-C bonds, respectively, thus greatly reducing the ICT resistance. Moreover, the Ti3C2Tx with rich surface groups (e.g., -OH, -F) and GO outer layers with an intertwined porous framework synergistically enable the pseudocapacitance dominated behavior, which is beneficial for fast lithium-ion storage. Accordingly, the as-made Si@MXene@GO anode exhibits considerably reinforced lithium-ion storage performance in terms of superior rate performance (1175.9 mA h g-1 at 5 A g-1) and long cycling stability (1087.6 mA h g-1 capacity retained after 1000 cycles at 2.0 A g-1). In-depth interfacial chemical composition analysis further reveals that an inorganically rich interphase with a gradient distribution of LiF and Li2O formed at the electrolyte/anode interface ensures mechanical stability during repeated cycles. This work paves a feasible way for maximizing the potential of SiO anodes toward fast-charging lithium-ion batteries.