Constructing carbon layer on SiO anode via interface engineering for high-performance lithium-ion batteries

• Construction of in situ carbon layer on the surface of SiO electrode. • The SiO/C anode exhibits both a high specific capacity and high energy density. • Completely isolated contact between the active material and the electrolyte. • Characterization of in situ EIS associated with battery cycling. Silicon monoxide (SiO) is a promising anode material for lithium-ion batteries due to its high specific capacity, abundant resources, and simple synthesis. However, its large volume change (∼200%) during cycling leads to unstable SEI formation and rapid capacity decay. Here, we propose an interface engineering strategy using carbon dots (CDs) to form a protective carbon layer on the SiO surface. This approach reduces electrolyte and active material consumption. The resulting SiO/C electrode delivers a high specific capacity of 1094 mAh g −1 after 300 cycles at a cycle rate of 0.4 C and achieves an energy density of 432.5 Wh kg −1 . In-situ electrochemical impedance spectroscopy reveals that the carbon coating facilitates faster charge transfer and alleviates mechanical stress during cycling. This work demonstrates a scalable and effective approach for improving the electrochemical performance of SiO anodes for next-generation lithium-ion batteries. The synthesis of Carbon dots is achieved through a hydroxyl aldehyde condensation reaction, which is subsequently employed to engineer carbon layer structures on the surface of SiO electrodes. The composite electrode exhibits a remarkable specific capacity of 1094 mAh g −1 after 300 cycles at cycle rate of 0.4 C, alongside a specific energy density of 432.5 Wh kg −1 for lithium-ion batteries.