An Ultrathin Asymmetric Solid Polymer Electrolyte with Intensified Ion Transport Regulated by Biomimetic Channels Enabling Wide‐Temperature High‐Voltage Lithium‐Metal Battery

Abstract

Lithium metal is being pursued extensively as a promising anode candidate to fabricate high energy density batteries owing to its ultrahigh specific capacity (3860 mAh g −1 ), lower density (0.59 g cm −3 ), and the lowest potential (−3.04 V vs H + /H 2 ). [1][2][3][4][5] Despite these outstanding merits, the commercialization of lithium metal batteries (LMBs) based on organic liquid electrolytes still confronting many great challenges, such as liquid leakage, flammability, and poor cycle ability, derived from the uncontrollable formation of Li dendrites. [6,7] Short circuits and severe heat release are generally caused by the continuous growth of Li dendrites, which will ignite the liquid organic electrolytes. [8,9] Solid-state electrolytes (i.e. polymer and ceramic electrolytes) may address these issues. [10][11][12][13] Compared with ceramic electrolytes, solid polymer electrolytes (SPEs) are considered as ideal candidates due to their low cost, ductility, and easy process ability. [14][15][16][17][18][19][20][21][22] However, their electrochemical stability and ionic conductivity need to be improved further to accelerate their applications in solid lithium metal batteries (SLMBs). [23][24][25][26] Even though SPEs are composed of many components, their electrochemical stability is mainly determined by the polymer matrices. [27,28] Many polymers of different electrochemical stability have been explored for the fabrication of LMBs since 1975. [29] However, no monophase polymer matrix was found to exhibit profound high-potential stability and reasonable lithium compatibility simultaneously due to its intrinsic limited energy gap. [30,31] Thus, LMBs with SPEs can only be constructed successfully by using modest potential cathodes, [32,33] which restricts their operating voltage and energy density. To improve the electrochemical stability of SPEs, numerous strategies have been proposed. For example, semi-interpenetrated polymer networks were proposed, [25,[34][35][36] but this strategy cannot intrinsically improve the electrochemical stability of the single polymer matrix, which would cause phase separation of Solid electrolytes that can be made compatible with high-voltage cathodes are greatly desired to increase the energy density of solid lithium metal batteries (SLMBs). However, no monophase polymer or ceramic examples can simultaneously exhibit strong electrochemical stability and reasonable lithium compatibility due to their limited internal energy gap. Herein, a novel asymmetric solid polymer electrolyte (AMSE) with tailored Li + transport mechanisms is proposed. It is composed of a high-voltage layer (HVL, polyacrylonitrile/ionic liquid [IL]) and lithium-compatible layer (LCL, poly(vinylidene fluoride-co-hexafluoropropylene)/UiO-66-SO 3 Li). The HVL exhibits a vehicular Li + transport mechanism with the introduction of IL, which achieves exceptional-electrochemical stability and reduced interfacial resistance. Due to the complexation between anions and UiO-66-SO 3 Li, a structural diffusion mechanism is ach...

Quasi‐Solid‐State Composite Electrolytes with Multifunctional 2D Molecular Brush Fillers for Long‐Cycling Lithium Metal Batteries†

“…[ 10 ] Furthermore, the strong polarization and electric field inside LMBs could generate serious lithium dendrites, which are prone to cause large‐scale internal short circuit and severe safety accident during continuous uncontrolled growth process. [ 11‐12 ] Solid‐state electrolytes with certain mechanical strength, such as inorganic ceramic electrolytes (ICEs), solid‐state polymer electrolytes (SPEs), and solid‐state composite electrolytes (SCEs), are ideal materials for suppressing the uncontrolled growth of lithium dendrites, which are considered as an effective strategy to solve above bottleneck issues. [ 13‐14 ] Compared with ICEs, SPEs show great development potential because of their low cost, good flexibility, and easy processability.…”

Heterojunction‐Accelerating Lithium Salt Dissociation in Polymer Solid Electrolytes

“…Solidstate lithium metal batteries (SSLMBs) have become next-generation energy storage devices with high expectations. [1,2] Solid state electrolytes, as key components of cells, have attracted considerable research interest owing to their ability to relieve safety issues and achieve high energy densities. [3][4][5] Solid state electrolytes can be classified into two main categories: ceramic and polymer solid electrolytes.…”

The Fabrication of in Situ Polymerization of 1,3-Dioxlane/Poly(vinyl alcohol)/Polyethylenimine Quasi-Solid Polymer Electrolyte for a Lithium Metal Battery Operated at Low Temperatures

“…In recent years, many researches have been devoted to improving the performance of electrolyte by combining the advantages of both liquid electrolyte and solid polymer electrolyte. , For example, Yao et al prepared a novel asymmetric ionogel electrolyte and achieved high ionic conductivity of 7.5 × 10 –4 S cm –1 at 20 °C and excellent cycling performance (the assembled NCM811/Li cell can operate stably over 150 cycles at 0.2 C) . In addition, quasi-solid polymer electrolyte (QSPE) as a kind of gel polymer electrolyte, which is generally composed of polymer, lithium salt, and plasticizer, has been extensively studied because of the high ionic conductivity and excellent safety. − For example, Li et al prepared QSPE by introducing ionic liquid into a polymer network and attained high ionic conductivity over 1 mS cm –1 at room temperature and 5.5 × 10 –5 S cm –1 at 0 °C .…”