A Flexible Si@C Electrode with Excellent Stability Employing an MXene as a Multifunctional Binder for Lithium-Ion Batteries.

Silicon is a promising anode material with high capacity for lithium-ion batteries (LIBs) but suffers from poor conductivity and large volume change during charge/discharge. Herein, by using two-dimensional conductive MXene as a multifunctional binder instead of conventional insulating polymer binders such as poly(vinylidene fluoride) or carboxymethylcellulose sodium (PVDF and CMC, respectively), a free-standing, flexible Si@C film was fabricated by simple vacuum filtration and directly used as anode for LIBs. In the MXene-bonded Si@C film, MXene constructed a three-dimensional conductive framework in which Si@C nanocomposites were embedded. Its loose and porous structure provided much space to buffer the large volume expansion of Si@C nanoparticles and thus led to significantly superior cycle stability compared with conventional CMC- and PVDF-bonded Si@C electrodes. Moreover, the porous structure and the metallically conductive MXene offered fast ion transport and outstanding conductivity of the MXene-bonded Si@C film, which were favorable for its rate performance. These results promise good potential of the MXene-bonded Si@C film electrode for LIBs.