Constructing a Stable Si-N-Enriched Interface Boosts Lithium Storage Kinetics in a Silicon-Based Anode.

Abstract

The stable operation of a SiOx anode largely depends on the intrinsic chemistry of the electrode/electrolyte interface; however, an unstable interface structure and undesirable parasitic reactions with the electrolyte of the SiOx anode often result in the formation of a fragile solid-electrolyte interphase (SEI) and serious capacity decay during the lithiation/delithiation process. Herein, a Si-N-enriched N-doped carbon coating is constructed on the surface of SiOx yolk-shell nanospheres (abbreviated as SiOx@NC) to optimize the SEI film. The two-dimensional covalently bound Si-N interface, on one hand, can suppress the interfacial reactivity of the SiOx anode to enable the formation of a thin SEI film with accelerated diffusion kinetics of ions and, on the other hand, acts as a Li+ conductor during the delithiation process, allowing Li+ to diffuse rapidly in the SiOx matrix, thereby improving the long-term cycling stability and rapid charge/discharge capability of the SiOx anode. A series of characterizations show that the interface charge-transfer barrier and the Li+ diffusion energy barrier through the SEI film are the main factors that determine the interfacial electrochemical behavior and lithium storage performance. This work clarifies the relationship between the SEI characteristics and the interfacial transfer dynamics and aims to offer a more basic basis for the screening of other electrode materials.