Stabilizing Li Metal Anodes through a Novel Self-Healing Strategy

Abstract

Poor stability is a long-standing problem preventing the practical application of Li metal anodes, which is fundamentally attributed to their fragile solid electrolyte interphase (SEI) layers that are intrinsically neither adaptable to the dynamic volume change nor self-healable after breakage. Here a Li metal anode is effectively stabilized by in situ integrating its SEI layer into a self-healable polydimethylsiloxane (PDMS) network cross-linked via imine bonding. The self-healing network enables the integrated SEI layer to readily accommodate the volume change but also to repair itself after breaking. Consequently, the resulting anode exhibits excellent cycling stability and a dendrite-free morphology. In a Li/LiFePO4 full cell, this strategy leads to capacity retention up to 99% and a Coulombic efficiency >99.5% after 300 cycles. Our investigation provides a novel self-healing strategy for developing stable Li-metal anodes aiming at high energy-density batteries.

High Stable Sulfur Cathode with Self‐Healable and Physical Confining Polydimethylsiloxane Interlayer

“…Firstly, the surface of sulfur microparticles was encapsulated with a PDMS nanoshell cross‐linked by dynamic imine bonding. The encapsulation was performed in ethyl acetate in the presence of sulfur powder, PDMS‐NH 2 , and terephthalaldehyde (Figure a) . The PDMS‐NH 2 was cross‐linked into a nanoshell with a thickness of 38 nm and homogeneously coated onto S microparticles to form a smooth appearance (Figure b–c, Figure S1 of Supporting Information).…”

“…The encapsulation was performed in ethyl acetate in the presence of sulfur powder, PDMS-NH 2 , and terephthalaldehyde ( Figure 1a). [33,34] The PDMS-NH 2 was cross-linked into a nanoshell with a thickness of 38 nm and homogeneously coated onto S microparticles to form a smooth appearance (Figure 1b-c, Figure S1 of Supporting Information). The existence of the PDMS nanoshell was confirmed by Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) (Figure 1d, Figure S2-3 of Supporting Information).…”

“…PDMS‐NH 2 (0.1–0.5 g) and sulfur microparticles (0.1–1.0 g) was added to ethyl acetate under stirring. Later terephthalaldehyde dissolved in ethyl acetate was slowly added to the above mixture . After stirring at room temperature for 12 h, the resulting mixture was filtered, washed with THF, and dried in vacuum to obtain PDMS encapsulated sulfur (S−PDMS) microparticles.…”

The Challenge of Lithium Metal Anodes for Practical Applications

“…With the protection of the porous PDMS film, the average CE of Li anode could reach 94.5% for over 200 cycles at a current density of 0.5 mA cm −2 . Cui et al further developed a kind of self‐healable network (PDMS‐1,4‐diformylbenzene (DFB)), which is cross‐linked between PDMS‐NH 2 and DFB via imine bonding. The self‐healing property of elastomer was achieved by fast transmission between imine (CN) bonds and amino/aldehyde (‐NH 2 /‐CHO) groups.…”

“…Copyright 2017, Wiley‐VCH. b) Reproduced with permission . Copyright 2018, American Chemical Society.…”