Lattice-Coupled Si/MXene Confined by Hard Carbon for Fast Sodium-Ion Conduction
Li Gou, Weifeng Jin, Ying Li, Mei Wang, Shengliang Hu, Huiqi Wang, Yan‐Bing He
Abstract
Silicon (Si) has been ascertained as one of the most desirable anode candidates for sodium-ion batteries (SIBs), ascribed to its sizeable theoretical capacity and abundant resource. However, the inherent electrochemical inertness of crystalline Si against sodium impedes its practical use. Herein, lattice-coupled Si nanoparticles are uniformly distributed onto delaminated MXene (d-MXene) and further tightly confined by hard carbon (HC), consequently forming a 3D cross-linked (Si/d-MXene)@HC architecture as an anode material for SIBs. Coupling a carbon-coated Si anode with a conductive d-MXene matrix through the local lattice overlapping not only vastly enables the alloying reactivity of Si with Na, but also provides fast-transfer portholes for Na+ and electrons because of the capacitive-like behavior of d-MXene, thus increasing the capacity and achieving fast ion conduction. The Si/d-MXene bonded with HC, constructing a robust architecture, can effectively stabilize the whole electrode structure and accommodate the volume expansion of Si upon cycling and increase capacitive-like contributions, resulting in an enhanced capacity and excellent cycle performance as anodes for SIBs. The developed electrode thus harvests favorable electrochemical performance compared to pure Si and d-MXene electrodes, such as high initial discharge capacity (370 mAh g–1), long cycling stability (a capacity retention above 80% after 500 cycles), and superior rate performance. The protocol to enable the sodium storage performance of Si/MXene anodes by adopting the capacitive-battery dual model would inspire rather far-ranging investigations on other advanced battery systems.