Synergistically Suppressing Lithium Dendrite Growth by Coating Poly‐l‐Lactic Acid on Sustainable Gel Polymer Electrolyte

Abstract

Lithium (Li) metal batteries are promising candidates in next‐generation high‐power energy storage devices. However, Li dendrite growth induces great safety issues. Herein, inspired by the high electrolyte uptake, high polarity of the cellulose derivative, and excellent mechanical properties of poly‐l‐lactic acid (PLLA), a sustainable multifunctional gel polymer electrolyte (GPE) through coating a thin PLLA film on the natural polymer is proposed for Li dendrite suppression and cycling stability improvement. In addition, PLLA film coating can also enhance the thermal stability and interfacial interaction between the PLLA‐coated GPEs and Li metal, thus improving the safety of the batteries. Due to these unique beneficial features, the green GPEs enable stable cycling of the Li metal anode with an enhanced Li+ transference number and coulombic efficiency during extended cycles and increases the lifetime by inhibiting short‐circuit failures even under a high energy density and extensive Li metal deposition.

Perspectives on Improving the Safety and Sustainability of High Voltage Lithium‐Ion Batteries Through the Electrolyte and Separator Region

“…[191] For practical applications in LIBs, GPEs must also have good mechanical and chemical stability, high ionic conductivity, high Li + transference numbers, and promote good interfacial contact with the electrode surfaces. [192] In recent years, there has been a great deal of research into the topic of GPEs, with studies demonstrating the application of GPEs in HV batteries with more common polymers (such as PEO, [193][194][195][196][197] PVDF, [198][199][200][201][202] and acrylate-based polymers such as polyacrylonitrile, PAN, [203][204][205][206][207] or poly(methyl methacrylate), PMMA), [208,209] as well as with more sustainable, biodegradable polymers such as cellulose [185,[210][211][212][213][214][215][216][217] or starch. [218,219] Some of these GPEs have even been capable of ionic conductivities comparable to commercial LEs (≈11.07 mS cm −1 for a 1 m LiPF 6 electrolyte in EC:DMC (1:1, v/v)).…”

Advances in Nanofibrous Materials for Stable Lithium-Metal Anodes

“…For GPE, the use of three-dimensional nanofiber networks as a skeleton can effectively improve its mechanical strength and thermal stability. − In addition, the abundant nanoscale or microscale pore structures of nanofiber films provide sufficient space for retaining liquid electrolytes, preventing them from leaking while also providing good interfacial compatibility. , As a typical example, Huang et al fabricated porous polyimide nanofiber films by electrospinning, and then added commercial electrolytes into the polyimide films . Under the promotion of lithium bis­(trifluoromethane)­sulfonimide (LiTFSI), the 1,3-dioxolane underwent self-polymerization, and finally a GPE with high room-temperature ion conductivity (2.9 × 10 –3 S cm –1 ), high strength (31 MPa), and high thermal stability (160 °C) was formed.…”

Lithium-ion battery separator membranes based on poly(L-lactic acid) biopolymer

“…These CA/PLLA/HNT composite nanofiber membranes have been used as green skeleton materials in GPEs for lithium-ion batteries in search for high performance and environmental sustainability [41]. Also, PLLA was successfully used as a coating in a GPE, in order to suppress the growth of lithium dendrites in the battery, allowing high electrolyte uptake and retention, thermal stability, electrochemical stability and Li + transference number [42]. Nevertheless, to our knowledge, there are still no applications of this polymer directly as separator membranes for lithium ion batteries or in the electrochemistry field.…”