Surface engineering enables robust SEI growth towards a stable and efficient lithium-ion battery SiOx anode

Abstract

It is challenging to enhance the cycling stability and rate capability of SiO_x (0 < x < 2) anodes for commercialization, due to the random and disordered growth of the solid electrolyte interphase (SEI) on the anode surface. Here, a surface engineering strategy was proposed to controllably regulate SEI formation. Through in situ constructing and densely coating a C–N network on the SiO_x nanoparticle surface, the surface energy and electronic structure were regulated, resulting in controlled growth of SEI components. The optimized SEI architecturally consists of inner Li₂O and an outer LiF/Li₂CO₃ mixture. It not only enables mechanical robustness but also suppresses electrolyte decomposition, which significantly improves the Li⁺ transport kinetics at the electrode/electrolyte interfaces, resulting in a 4-fold reduced interfacial charge transfer resistance. Consequently, the anode exhibits outstanding electrochemical performance, with an initial reversible capacity of 1674 mAh g⁻¹. Moreover, the high capacities of 1618 mAh g⁻¹, 1274 mAh g⁻¹ and 1114 mAh g⁻¹ were recorded at the 100th, 200th, and 300th cycles with a 1 A g⁻¹ current density, respectively. The capacity retention rates were 96%, 83%, and 66%, respectively, which demonstrates good cycling stability. Besides, the rate capability approached 888 mAh g⁻¹ at 5 A g⁻¹ and recovered 98% as the current decreased to 0.1 A g⁻¹. More importantly, this method is low-cost, scalable, and uniform, making it suitable for large-scale industrial applications. This work provides a new way of producing high-performance SiO_x anodes; moreover, the scalable fabrication is promising for industrial applications.