Enhanced lithium-ion storage of the SiO_x@C anode enabled by carbon coating coupled with MXene as a conductive binder

SiOx is a promising anode material for lithium-ion batteries owing to its high theoretical capacity (2680 mA h g(-1)), but it suffers from unsatisfactory cycling stability and rate capability caused by large volume changes during lithiation/delithiation and low electronic conductivity. Here, with low-density polyethylene as the carbon source, carbon-coated SiOx (SiOx@C) particles with Si-C bond at the interface are prepared, in which the carbon coating can significantly improve the conductivity and suppress the volume expansion of SiOx. Furthermore, the SiOx@C electrode is assembled with Ti3C2Tx MXene nanosheets as a multi-functional conductive binder via the conventional homogenizing-coating method. In the MXene-bonded SiOx@C electrode, the SiOx@C particles are embedded into the highly conductive MXene framework, which simultaneously facilitates fast electron transfer and ion diffusion, buffers the volume expansion of SiOx@C, and provides additional porosity for fully exposing active sites. Benefiting from the combination of carbon coating and the MXene binder, the MXene-bonded SiOx@C electrode displays excellent electrochemical performance for lithium-ion storage with a high reversible capacity (1363.3 mA h g(-1) at 0.1 A g(-1)), outstanding cycling stability (962.7 mA h g(-1) after 300 cycles at 0.8 A g(-1)) and superior rate performance (604.5 mA h g(-1) at 6.4 A g(-1)). This work not only provides a promising anode material for high-energy-density lithium-ion batteries, but also proposes a strategy for constructing silicon-based electrodes with an MXene as a multi-functional binder.