Engineering Solid Electrolyte Interphase on Red Phosphorus for Long-Term and High-Capacity Sodium Storage

Solid electrolyte interphase (SEI) makes a critical impact on the cyclic property of anodes for both lithium and sodium-ion batteries (LIBs/SIBs), which is more significant for high-capacity anodes. Unfortunately, it is arduous to control the components of SEI and its arrangement due to the unstable interface resulting from the decomposition, rupture, and re-generation of SEI and the complex chemical environment. Here, we report a synergistic in situ and ex situ strategy to tai-lor the interface of an active material, which enables SEI with superb mechanical behavior to form in the Helmholtz re-gion around interface. The amorphous TiO2 as a protection layer shows strong interaction with the reduction product (i.e., NaF) of fluoroethylene carbonate additive, which enhances the adhesion of SEI to the electrode material. The shed-ding of SEI during the huge volume expansion of active material is substantially suppressed. Furthermore, the toughness of SEI is increased by the binding of NaF with the organic co...