Mechanically Interlocked Interphase with Energy Dissipation and Fast Li-Ion Transport for High-Capacity Lithium Metal Batteries

Abstract

Constructing an artificial solid electrolyte interphase (ASEI) on Li metal anodes (LMAs) is a potential strategy for addressing the dendrite issues. However, the mechanical fatigue of the ASEI caused by stress accumulation under the repeated deformation from the Li plating/stripping is not taken seriously. Herein, this work introduces a mechanically interlocked [an]daisy chain network (DCMIN) into the ASEI to stabilize the Li metal/ASEI interface by combining the functions of energy dissipation and fast Li-ion transport. The DCMIN featured by large-range molecular motions is cross-linked via efficient thiol-ene click chemistry; thus, the DCMIN has flexibility and excellent mechanical properties. As an ASEI, the crown ether units in DCMIN not only interact with the dialkylammonium of a flexible chain, forming the energy dissipation behavior but also coordinate with Li ion to support the fast Li-ion transport in DCMIN. Therefore, a stable 2800 h-symmetrical cycling (1 mA cm−2) and an excellent 5 C-rate (full cell with LiFePO4) performance are achieved by DCMIN-based ASEI. Furthermore, the 1-Ah pouch cell (LiNi0.88Co0.09Mn0.03O2 cathode) with DCMIN-coated LMA exhibits improved capacity retention (88%) relative to the Control. The molecular design of DCMIN provides new insights into the optimization of an ASEI for high-energy LMAs.