Polymer-in-salt solid electrolytes for lithium-ion batteries

Abstract

Solid-state polymer lithium-ion batteries with better safety and higher energy density are one of the most promising batteries, which are expected to power future electric vehicles and smart grids. However, the low ionic conductivity at room temperature of solid polymer electrolytes (SPEs) decelerates the entry of such batteries into the market. Creating polymer-in-salt solid electrolytes (PISSEs) where the lithium salt contents exceed 50[Formula: see text]wt.% is a viable technology to enhance ionic conductivity at room temperature of SPEs, which is also suitable for scalable production. In this review, we first clarify the structure and ionic conductivity mechanism of PISSEs by analyzing the interactions between lithium salt and polymer matrix. Then, the recent advances on polyacrylonitrile (PAN)-based PISSEs and polycarbonate derivative-based PISSEs will be reviewed. Finally, we propose possible directions and opportunities to accelerate the commercializing of PISSEs for solid polymer Li-ion batteries.

Designing Polymer‐in‐Salt Electrolyte and Fully Infiltrated 3D Electrode for Integrated Solid‐State Lithium Batteries

“…More importantly, the formation of aggregated ionic clusters can restrict the movement of TFSI À and rapidly transport Li + . [25,30] In addition to high ionic conductivity and good t Li þ , PVHLi-1.1 electrolyte membrane possesses good electrochemical stability. In the linear sweep voltammetry (LSV) measurements (Figure 3 f and S7), a mild current peak is observed at 4.1 V for the liquid electrolyte, while the PVHLi-1.1 is stable up to 4.7 V without obvious current fluctuation.…”

“…Compared to the low Li salt concentration SPEs with low ionic conductivities arising merely from the segmental polymer chains (associate with and dissociate from Li + ), the ionic conductivity in PISSEs significantly benefits from the motion of Li + through fast ion transport channels created by aggregated cation/anion clusters. [24,25,50] The activation energy (E a ) of different PVHLi-x electrolytes was calculated by the Arrhenius formula and listed in Table S1. Because of the least resistance to segmental motion and unique Li + transport pathway in PISSEs, the PVHLi-1.1 has the lowest migration barrier for ion transport.…”

“…%), despite being rarely investigated, has great potentials because it can achieve high ionic conductivity at RT via a facile and quite straightforward way. [23][24][25] In this system, the proportion of amorphous regions has been maximized due to the complete interaction between sufficient lithium salt and the polymer matrix. Besides, the transport of lithium ions is achieved not only by the movement of the amorphous regions of the polymer but also through the unique ionic channel constructed by ion clusters (Figure 1 b).…”

“…Besides, the transport of lithium ions is achieved not only by the movement of the amorphous regions of the polymer but also through the unique ionic channel constructed by ion clusters (Figure 1 b). [24][25][26] Till now, a few polymer matrices, [25b, 26-30] especially polycarbonates, [27] have been utilized in PISSEs with satisfactory ionic conductivity at RT. Nevertheless, their mechanical properties were deteriorated, which is caused by ultrahigh concentration of Li salt in PISSEs.…”

Surface and Interface Engineering of Nanoarrays toward Advanced Electrodes and Electrochemical Energy Storage Devices

“…However, liquid electrolytes are not ideal for realizing flexible devices because of poor thermal stability and the risk of leakage and electrolyte fluctuation during device movement such as bending, rolling, folding, and twisting. [129][130][131] Using (quasi-)solid-state electrolytes such as polymer electrolytes will effectively address these issues and endow the device with multi-functionality. In particular, when 3D-NAs are utilized, it is highly possible that solid-state electrolytes and electrode nanostructures will attain close interfacial contact, similar to the liquid electrolyte cases, which is quite different from the limited contact in traditional powder electrodes (Figure 9a 1 ).…”