Dual mechanism of electrostatic shielding and iodide redox for self-healing lithium metal anodes

Abstract

Uncontrollable lithium dendrite growth and interfacial parasitic reaction hinder the development of lithium metal batteries (LMBs). The 15-Crown-5 (15-C-5) has shown potential to inhibit dendrite growth due to a self-healing electrostatic shielding (SHES) mechanism. The strong complexation of 15-C-5 with Li+ induces to generate a Li2O-dominated solid electrolyte interphase (SEI), leading to a dramatic increase in inactive Li and dead Li. Meanwhile, the inhomogeneous SEI causes whisker Li tip deposition, which increases the contact specific surface area between the electrolyte and Li, further intensifies electrolyte consumption. This has impeded the development of 15-C-5 electrolyte. Therefore, we propose to add I3–/I– redox to eliminate the negative effect of 15-C-5, including several advantages: the rescuing engineering of inactive Li and dead Li during deposition process; the promotion of columnar Li tips deposition and the circumvention of electrolyte consumption; enhancing SEI mechanical strength and lowering the Li nucleation barrier. The SHES mechanism occurrs during Li deposition and I3–/I– redox works during Li stripping. Boosted interfacial stability and cycle life can be retained due to the dual mechanism effect of SHES and I3–/I– redox. The work provides a dual-mechanism strategy from optimizing electrolytes to deep the insight into the research toward self-healing lithium metal anodes.