Stabilizing Lithium Metal Anodes by a Self-Healable and Li-Regulating Interlayer

Abstract

Lithium (Li) metal is a promising anode for highenergy-density batteries, but its practical applications are severely hindered by side reactions and dendrite growth at the electrode/ electrolyte interfaces. Herein, we propose that the problems can be effectively solved by introducing an interlayer. The interlayer is composed of a trifluorophenyl-modified poly(ethylene imine) network cross-linked by dynamic imine bonding (PEI-3F). The trifluorophenyl moieties of the interlayer can coordinate with Li + , which enables the interlayer to adjust the distribution of Li + at the electrode/electrolyte interface, while the imine bonding endows the interlayer with self-healing capability. The resulting Li anodes exhibit excellent cycling stability (250 cycles in asymmetric Li||Cu cells) and dendrite-free morphologies. A lithium sulfur (Li-S) cell that uses anodes shows a retention rate of 91% after 100 cycles with a high sulfur loading (5 mg cm −2 ). This study provides a novel strategy to concern the intrinsic drawbacks of a lithium metal anode, which can be extended to other light-metal electrodes aiming for high energy-density batteries.

Intrinsically Self-Healing Polymers: From Mechanistic Insight to Current Challenges

“…The distribution of Li + at the electrode/ electrolyte interface can be better adjusted, and self-healing ability achieves recovery of interlayer even after being damaged by a Li dendrite. 191 Recently, a readily synthesized copolymer network endowed with simultaneously high ionic conductivity and good self-healability at relatively low temperature is fabricated based on the weak but abundant hydrogen-bonding units (Figure 19c,d). 192 The assembled Li-metal battery with such a protective layer shows superior electrochemical performance than that with bare a Li-metal electrode, even at relatively low temperature of 5 °C, as shown in Figure 19e.…”

Stabilizing Li Plating by a Fluorinated Hybrid Protective Layer

“…To show our modification effect more intuitively, we compared the battery cycle performance with the previous interface modification work (Table ). Under the same working conditions, the cycle life and cycle stability of the MgF 2 @Li electrodes are better. ,,− From the above voltage profile data of the symmetrical cells, we can see that the MgF 2 @Li electrodes have higher cycle stability and smaller cycle overpotential due to the existence of Li 3 Mg 7 and LiF. The low cycle life of pristine Li electrodes may be due to the spontaneously formed fragile protective layer, which is constantly ruptured and repaired with repeated Li deposition and stripping, causing continuous and irreversible loss of electrolyte.…”

Self-Healable Lithium-Ion Batteries: A Review

“…Recently, a poly (ethylene imine) (PEI) interlayer, cross-linked by imine bonding, was introduced on Li anodes to endow the SEI layer with self-healing capabilities [ 105 ]. Together with the trifluorophenyl moieties which can coordinate with Li + , the Li-PEI-3F anode showed good cycling stability (600 h in the symmetric Li||Li cells at 1.0 mAh cm −2 ).…”