Constructing multifunctional solid electrolyte interface via in-situ polymerization for dendrite-free and low N/P ratio lithium metal batteries.

Stable solid electrolyte interface (SEI) is highly sought after for lithium metal batteries (LMB) owing to its efficient electrolyte consumption suppression and Li dendrite growth inhibition. However, current design strategies can hardly endow a multifunctional SEI formation due to the non-uniform, low flexible film formation and limited capability to alter Li nucleation/growth orientation, which results in unconstrained dendrite growth and short cycling stability. Herein, we present a novel strategy to employ electrolyte additives containing catechol and acrylic groups to construct a stable multifunctional SEI by in-situ anionic polymerization. This self-smoothing and robust SEI offers multiple sites for Li adsorption and steric repulsion to constrain nucleation/growth process, leading to homogenized Li nanosphere formation. This isotropic nanosphere offers non-preferred Li growth orientation, rendering uniform Li deposition to achieve a dendrite-free anode. Attributed to these superiorities, a remarkable cycling performance can be obtained, i.e., high current density up to 10 mA cm-2, ultra-long cycle life over 8500 hrs operation, high cumulative capacity over 4.25 Ah cm-2 and stable cycling under 60 °C. A prolonged lifespan can also be achieved in Li-S and Li-LiFePO4 cells under lean electrolyte content, low N/P ratio or high temperature conditions. This facile strategy also promotes the practical application of LMB and enlightens the SEI design in related fields.

Polymer Electrolyte Film as Robust and Deformable Artificial Protective Layer for High-Performance Lithium Metal Anode.

Lithium (Li) metal anode is a promising candidate for next-generation high capacity energy storage systems. Unfortunately, the uneven deposition/dissolution of Li metal hinders its wide applications. Herein, a robust and deformable polymer electrolyte film as the advanced protective layer on Li metal is developed by a simple tape-casting method, in which the polymer endows a comfortable interfacial contact as well as membrane flexibility to adapt the volume change, while the coordination between the polymer and Li salt provides fast Li+ ion diffusion channels. The modified Li metal anodes deliver a stable cycling over 1000 cycles under a high current density of 3 mA cm-2 in the ether-based electrolyte. The enhanced cycling performance at high current densities are mainly attributed to the Li plating occurred beneath the ion-conducting protective layer, which facilitates Li+ ion uniform distribution and further suppresses Li dendrite growth. Accordingly, constructing a polymer electrolyte protective film onto the Li metal anodes is a facile and low-cost methodology to drive the Li metal anode toward practical application.