Poly(vinylidene fluoride-co-hexafluoropropylene)-Based Solid Polymer Electrolyte Incorporated with UiO-66 for Lithium Metal Batteries

Abstract

All-solid-state lithium metal batteries (ASSLMBs) have garnered significant interest as a result of their enhanced safety features and higher energy density compared to traditional lithium-ion batteries with liquid electrolytes. Nonetheless, a substantial challenge within ASSLMBs lies in the constrained lithium-ion flux encountered in solid-state polymer electrolytes, resulting in subpar performance during high-current charging and discharging scenarios. This limitation detrimentally affects the electrochemical performance of ASSLMBs. In this present work, we introduce a novel composite solid polymer electrolyte (CSPE) comprising metal–organic frameworks, namely, UiO-66, poly­(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), and lithium bis­(trifluoromethane)-sulfonimide (LiTFSI) (referred to as UPH-SPE). UPH-SPE containing 5 wt % UiO-66 demonstrates exceptional characteristics, including a high ionic conductivity of 4.7 × 10–4 S cm–1, an electrochemical stability window of 4.9 V, and a remarkable lithium-ion transference number of 0.58 at 25 °C. Full cell tests unequivocally showcase that these newly developed composite electrolytes exhibit significantly improved performance in terms of the rate capability and cycling stability at room temperature. Specifically, the discharge capacity of ASSLMBs with UPH-SPE remains at 140 mAh g–1 when operated at a current density of 0.5 C over 100 cycles. Even after 200 cycles, the capacity is sustained at 94 mAh g–1. This study underscores the potential of our CSPE film to advance the practical application of ASSLMBs, offering promising prospects for future developments in this field.

2023 Pioneers in Energy Research: Shizhang Qiao

“…The Se–W 2 N/C cathode displays an exceptional performance with a reversible capacity. In the frame of lithium all-solid-state battery development, Liu et al introduced a novel composite solid polymer electrolyte (CSPE) comprising metal–organic frameworks, namely, UiO-66, poly­(vinylidene fluoride- co -hexafluoropropylene) (PVDF-HFP), and lithium bis­(trifluoromethane)-sulfonimide (LiTFSI) (referred to as UPH-SPE). This novel electrolyte demonstrates a high ionic conductivity, a large electrochemical stability window, and a remarkable lithium-ion transference number.…”

Preparation of Main-Chain Fluorinated Alternating Polymer by START Polymerization for All-Solid-State Electrolytes

“…Solid electrolytes can be mainly divided into two categories: solid polymer electrolytes (SPEs) and solid inorganic electrolytes (SIEs). − SPEs own many advantages such as good interface contact, high electrochemical stability, excellent processability, and low cost due to which SPEs have garnered widespread research attention . Among all of the polymer electrolytes studied, poly­(ethylene oxide) (PEO) was the most used due to its excellent solvation effect toward Li + and electrode interface compatibility. − However, it generally exhibited poor oxidative and thermal stability, limited Li + transference number ( t Li + ) due to its high crystallinity, and low conductivity at room temperature. , To prepare PEO-based electrolytes with high conductivity and sufficient mechanical strength, various strategies including copolymerization, − blending, , addition of inorganic particles, − cross-linking, and other methods , have been developed.…”