Artificial Solid‐Electrolyte Interphase for Lithium Metal Batteries

Abstract

Li metal has attracted intense attention due to its high specific capacity, but the dendrite growth during cycling impedes its practical application as a rechargeable anode. To improve the stability of the solid‐electrolyte interphase (SEI) on Li metal is the key to develop Li anode with high safety. In native SEI, inorganics act as fast ion channels and organics play the role of soft base with high flexibility to buffer volume change. However, the SEI with inorganics close to Li surface and organics close to electrolyte always leads to a fragile structure, resulting in repeatedly breaking and growing of the surface layer. Artificial SEI is one of the most effective ways to improve interphase stability and extend the cycle life of Li anode. Inorganics such as Li fluoride, Li nitride, Li phosphate and Li alloys have been widely applied in Li protection. In situ chemical reactions, spin coating and doctor blade coating of organics were also conducted to obtain SEI with high lithiophilic functional groups and high elasticity. To fabricate an ideal artificial SEI, organic and inorganic components should be rearranged as a rational structure to possess synergetic effects with both high flexibility and ionic conductivity. This Minireview summarizes the most recent works on artificial SEI and discusses the electrochemical performance of different components as interphase, aiming to inspire the study on designing and fabricating stable Li anode with robust interphase structure.

Constructing nitrided interfaces for stabilizing Li metal electrodes in liquid electrolytes

“…Since the formation of the SEI is a key factor in controlling the surface properties of Li, one of the effective approaches to stabilize Li metal electrode is to construct functional artificial SEI layers on its surfaces. 28,35,43,63,64 According to the preparation mechanism, the strategies to develop nitrided artificial SEI can be divided into physical methods and chemical methods.…”

Molecular Engineering Approaches to Fabricate Artificial Solid‐Electrolyte Interphases on Anodes for Li‐Ion Batteries: A Critical Review

“…Some excellent recent reviews summarize the current development, design and improvement of Art-SEIs. [26,27,28,99,[108][109][110][111][112][113][114] In contrast, our present review mainly focuses on the reality check of Art-SEI materials and methods toward real-world applications. Specifically, in this chapter, Art-SEI engineering approaches are reviewed from a practical perspective, divided into top-down and bottom-up methods.…”

Engineering and characterization of interphases for lithium metal anodes

“…With continuously formation of SEI, 6 Li: 7 Li ratio in electrolyte would decrease over time. On the copper surface, 6 Li: 7 Li ratio in initially formed SEI would higher than that of subsequently formed. By analyzing ToF-SIMS result combined with XPS as shown in Figure 11a, they proposed that the direct time sequence of SEI formation in different layer on Cu surface that SEI growth follows a "bottom-up" mechanism: the organic components formed first on the electrode; then, the inorganic components formed underneath the organic layer and push the as-formed layer up as the SEI grows.…”

“…4,5 Another approach is by coating artificial SEIs to obtain controllable composition and structure. 6 In recent decade, numerous achievements have been made regarding to the SEI engineering and the LMBs electrochemical performance. 7 At same time, continued efforts have been made on the fundamental understanding of this significant component, SEI.…”

“…Figure 11. (a)6 Li:7 Li ratio and Cu + , C2H2 -(organic), Li2F-(inorganic), and Cu + . Intensities were normalized to total ion counts.…”