Fatigue-Free and Skin-like Supramolecular Ion-Conductive Elastomeric Interphases for Stable Lithium Metal Batteries

Abstract

The heterogeneity and continuous cracking of the static solid electrolyte interphase (SEI) are one of the most critical barriers that largely limit the cycle life of lithium (Li) metal batteries. Herein, we report a fatigue-free dynamic supramolecular ion-conductive elastomeric interphase (DSIEI) for a highly efficient and dendrite-free lithium metal anode. The soft phase poly­(propylene glycol) backbone with loosely Li+–O coordinating interaction was responsible for fast ion transport. Simultaneously, the supramolecular quadruple hydrogen bonds (H-bonds) in the hard phases endow the elastomeric interphase with mechanical enhancement, while gradient H-bonds can dissipate strain energy via the sequential bonding cleavage. Such a design affords superior mechanical robustness, high ionic conductivity, gradient energy dissipation, and high Li+ transference number. Besides, anion enrichment in DSIEI assists in situ construction of a lithium fluoride-rich inner layer upon cycling. The resultant biomimetic bilayer structure enables the symmetric cells with superior cyclability of over 600 h at a high current density of 10 mA cm–2. Moreover, the DSIEI allows stable operation of the full cells under constrained conditions of limited lithium excess, a high-loading LiNi0.8Co0.1Mn0.1O2 cathode, and a low negative/positive capacity (N/P) ratio. This work presents a powerful strategy for deigning artificial SEI and achieving high-energy-density Li metal batteries.

Molecular Engineering toward Robust Solid Electrolyte Interphase for Lithium Metal Batteries

“…[113,114] Subsequently, a polymer passivation layer with high mechanical and ionic conductivity is formed on the Li metal surface, which minimizes the continuous decomposition of the electrolyte and generates a stable SEI. [53,115] Owing to the simplicity of the process, electrochemical polymerization is a short-cut to inhibit the growth of Li dendrites and increase the energy density of LMBs in the future. [31,116] Some ingenious designs were reported to minimize the growth of Li dendrites by electrochemical polymerization methods.…”

“…Figure a,b presents the cycling properties of the Li symmetric cells and LMB full‐cells in recent years. [ 37,44–71 ] The durability of Li symmetric cells requires enhancement, especially at high current densities and area capacities. The electrochemical performance of most LMB full‐cells is concentrated in the range of <1000 cycles, <3 C current density, and <200 mAh g −1 capacity.…”

“…a) The cycling properties of the Li symmetric cells and b) LMB full‐cells based on molecular design. [ 37,44–71 ] c) A comparison of the energy density of the current state‐of‐the‐art LMB‐based pouch cells. [ 28,72–89 ]…”

High-Toughness and Intrinsically Self-Healing Cross-Linked Polyurea Elastomers with Dynamic Sextuple H-Bonds

“…Good tunable mechanical strength, outstanding toughness, and satisfactory elasticity are the most significant features of elastomers that permit their application in impact-resistant environments, , soft robots, − wearable electronics, − etc. More importantly, the crack-resistance, self-healing, environmental friendliness, reliability, and safety of the elastomers are demanded .…”

One-Dimensional Oxide Nanostructures Possessing Reactive Surface Defects Enabled a Lithium-Rich Region and High-Voltage Stability for All-Solid-State Composite Electrolytes

“…Considered as one of the “ultimate solutions”, solid electrolytes substantially improve the safety and energy density of batteries by replacing flammable liquid organic electrolytes. , In various electrolyte systems, solid polymer electrolytes stand out owing to their high flexibility and excellent interfacial compatibility, which satisfy most industrial requirements. , However, polymer electrolytes usually suffer from low ionic conductivity at room temperature, poor stability under high-voltage conditions, and severe lithium-dendrite-induced short circuits. Therefore, the enhancement of ion-transport kinetics through multiple strategies, especially chemical interactions and structural designs, has become an essential direction for research breakthroughs.…”