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The safety concerns associated with power batteries have prompted significant interest in all−solid−state lithium batteries (ASSBs). However, the advancement of ASSBs has been significantly impeded due to their unsatisfactory electrochemical performance, which is attributed to the challenging interface between the solid−state electrolyte and the electrodes. In this work, an in situ polymerized composite solid−state electrolyte (LLZTO−PVC) consisting of poly(vinylene carbonate) (PVC) and Li6.4La3Zr1.4Ta0.6O12 (LLZTO) was successfully prepared by a γ−ray irradiation technique. The novel technique successfully solved the problem of rigidity at the interface between the electrode and electrolyte. The LLZTO−PVC electrolyte exhibited a notable ionic conductivity of 1.2 × 10−4 S cm−1 25 °C, along with good mechanical strength and flexibility and an electrochemical window exceeding 4.65 V. It was showed that the LiCoO2(LCO)/LLZTO−PVC/Li battery, which achieved in situ solidification via γ−ray irradiation, can steadily work at a current density of 0.2 C at 25 °C and maintain a retention rate of 92.4% over 100 cycles. The good interfacial compatibility between electrodes and LLZTO−PVC electrolyte designed via in situ γ−ray irradiation polymerization could be attributed to its excellent electrochemical performance. Therefore, the method of in situ γ−ray irradiation polymerization provides a vital reference for solving the interface problem. [ABSTRACT FROM AUTHOR]

Highlights: The mechanism of the change in lithium-ion transport behavior caused by the incorporation of inorganic fillers into the polymer matrix is reviewed. The intrinsic factors of inorganic fillers to enhance the ionic conductivity of composite polymer electrolyte (CPEs) are investigated in depth. The contribution of inorganic fillers to inhibit dendrite growth and side reactions in CPEs is summarized. With excellent energy densities and highly safe performance, solid-state lithium batteries (SSLBs) have been hailed as promising energy storage devices. Solid-state electrolyte is the core component of SSLBs and plays an essential role in the safety and electrochemical performance of the cells. Composite polymer electrolytes (CPEs) are considered as one of the most promising candidates among all solid-state electrolytes due to their excellent comprehensive performance. In this review, we briefly introduce the components of CPEs, such as the polymer matrix and the species of fillers, as well as the integration of fillers in the polymers. In particular, we focus on the two major obstacles that affect the development of CPEs: the low ionic conductivity of the electrolyte and high interfacial impedance. We provide insight into the factors influencing ionic conductivity, in terms of macroscopic and microscopic aspects, including the aggregated structure of the polymer, ion migration rate and carrier concentration. In addition, we also discuss the electrode–electrolyte interface and summarize methods for improving this interface. It is expected that this review will provide feasible solutions for modifying CPEs through further understanding of the ion conduction mechanism in CPEs and for improving the compatibility of the electrode–electrolyte interface. [ABSTRACT FROM AUTHOR]

Polyethylene oxide (PEO) is considered as the most promising and widely studies polymer matrix. However, its practical application is limited for its low ionic conductivity at room temperature. Here, a novel fluorinated branched (2,2,2-Trifluoroethyl methacrylate (TFEMA)) ether polymer (PFP) was synthesized through thiol-Michael addition click reaction and blended with PEO to obtained PEO-based polymer electrolyte. The introduction of PFP could reduce the crystallinity and hinder the migration of anions, resulting in a double increase in ionic conductivity and lithium-ion transference number. More importantly, the symmetric Li/Li employing blended polymer shows stable cycle more than 1700 h and the Li/LiFePO 4 cell shows the superior performance of both cycling and rating at 60 °C. Even at lower temperature (28 °C), the Li/LiFePO 4 cell exhibits encouraging cycling performance with 88.6% capacity retention at 0.2C after 100 cycles. This study provides a novel strategy for structural design and synthesis progress of solid polymer electrolyte. • PFP is synthesized by thiol-Michael addition click reaction, without any specialized energy required. • Branched structure reduced crystallinity of PEO and δ = 3.16 × 10−5 S cm−1 at 30 °C, which is an order of magnitude higher. • The polar groups in PFP optimal ionic conduction, resulting in the increase of lithium-ion transference number. • δ = 1.66 × 10−4 S cm−1 and t Li+ = 0.30 at 45 °C, which can benefit for the stable cycle of solid-state battery. [ABSTRACT FROM AUTHOR]

A novel quasi solid single‐ion polymer electrolyte with semi‐interpenetrating network (semi‐IPN) structure has been prepared. The lithium‐ion conduction membrane is composed of both the cross‐linked lithiated poly‐2‐acrylamido‐2‐methylpropane sulfonic acid (PAMPS‐Li) as a polyanionic single‐ion lithium salt source and the high molecular weight polyethylene oxide (PEO) as a polymer matrix, in which the two components show great compatibility due to the special semi‐IPN structure. For such quasi‐solid electrolyte system, we have particularly studied the crystallinity variety and ionic conductivity change with a series of polymer salt concentration. The results show that the electrolyte has an appropriate mechanical stability, minimal crystallinity, and acceptable ionic conductivity of 1.34×10−5 S/cm at 60 °C. Furthermore, the lithium‐ion conduction membrane shows the lithium‐ion dominating conductive property and high transport number of 0.77. Moreover, the LiFePO4/Li batteries' cycle results show a high discharge capacity of 140.0 mAh/g and a retention of 90.4 % after 100 cycles at the rate of 0.2 C. [ABSTRACT FROM AUTHOR]

The application of PEO-based solid polymer electrolyte (SPE) is limited by the low ionic conductivity and lithium-ion transference number near room temperature. In this paper, a pendant polyether poly (EO- co -PCGE) (PECP) with low molecular weight is prepared by copolymerization of ethylene oxide (EO) monomer with typical lithium-ion conduction group and propylene carbonate glycidyl ether (PCGE) monomer with high dielectric group. By blended with PECP, the PEO-based SPE is obtained and its ionic conductivity can be increased to 3.54 × 10−5 S cm−1 at room temperature and 1.32 × 10−4 S cm−1 at 40 °C. In one aspect, the pendant structure and low molecular weight are beneficial to the reduction of the crystallinity of PEO matrix; in a further aspect, the cyclic carbonate pendant offers a competitive effect on segmental motion and the lithium-ion complexation of PEO, thus affecting the conduction mechanism of lithium-ions in the conventional PEO-based SPE and significantly increasing the lithium-ion transference number. The synergistic effect of these two aspects makes the prepared PEO-based SPE have excellent properties of ionic conduction especially at room temperature, and the LiFePO 4 /Li batteries with the SPE present excellent cycling performance at the temperature of 40 °C with a discharge capacity of about 100 mA h g−1 after 150 battery cycles. [Display omitted] • Copolyether with low molecular weight is conducive to reducing crystallinity of SPE. • Pendant cyclic carbonate can affect the conduction of Li + thus improving t Li +. • Ionic conductivity could be greatly increased by the synergistic effect of above two. • σ = 3.54 × 10−5 S cm−1 at room temperature, over one order of magnitude higher. • σ = 1.32 × 10−4 S cm−1 at 40 °C which can support the cycling of solid-state battery. [ABSTRACT FROM AUTHOR]

A new lithiated-interpenetrating network gel-polymer electrolytes (LIPN-GPEs) is designed and fabricated by ultraviolet-irradiation radical polymerization. The LIPN-GPEs includes both cross-linked poly (lithiated 2-acrylamido-2-methylpropane sulfonic acid- co -polyethylene glycol acrylate) matrix C–P(AMPSLi-MPEGA) and polyacrylonitrile (C-PAN), which forms the interpenetrating framework. The interpenetrating network ensures the mechanical strength and flexibility that eliminates volume changes of lithium anode during lithium deposition/stripping process. Meanwhile, the LIPN-GPEs with better self-supporting nature and high ionic conductivity (2.5 × 10−3 S/cm) can promote the movement of lithium ion resulting in more uniform distribution, which realizes uniform lithium deposition with stable SEI composition. Therefore, the LIPN-GPEs indicates excellent interfacial stability towards lithium anode. Symmetrical lithium metal cell yields low overpotential of 50 mV over 4000 h at 0.5 mA cm−2. The LIPN-GPEs with optimized ratio exhibits wider electrochemical window (5.06 V vs. Li/Li+) at ambient temperature, which also possesses unexceptional thermal stability with decomposition temperature up to 400 °C. Especially, when assembled with high-voltage cathode LiCoO 2 (LCO) and LiNi 0.5 Co 0. 2 Mn 0. 3 O 2 (NCM523) as coin cells, the LIPN-GPEs reveals cycling performance, reflecting good high-voltage resistance characteristic. This work testifies that LIPN-GPEs through a convenient ultraviolet-irradiation radical polymerization provides a candidate for lithium metal battery, which furnishes application prospects in wearable devices. • The strength and flexibility eliminates the volume changes of lithium anode. • The LIPN-GPEs realizes excellent uniform lithium deposition with 4000 h. • The LIPN-GPEs exhibits better self-supporting nature and high ionic conductivity. • The LIPN-GPEs reflects fantastic high-voltage resistance characteristic. [ABSTRACT FROM AUTHOR]

Single ion conductor has been realized as a new path to reduce polarization and improve electrochemical performance of the lithium ion batteries (LIBs). In this work, a novel single ion conductor gel polymer electrolyte (SIGPE) was designed via free radical polymerization, co-electrospinning and plasticizing process. The molecular structure information of the single ion polyanionic salt P(MPEGA-AMPSLi) of the SIGPE is carefully verified. The SIGPE shows high ionic conductivity of around 2.8 × 10−5 S/cm at 25 °C, high lithium ion transference number of 0.75, wide electrochemical window of 4.7 V as well as a stable cycle performance at 25 °C and 60 °C. The plasticizing mechanism of the gel polymer electrolyte has also been modeled and studied theoretically by molecular dynamics simulation. The results display a positive effect of the plasticizing in promoting the ionization of Li ions, increasing the diffusion coefficient of Li ions from 8.05 × 10−11 cm2/s to 1.37 × 10−9 cm2/s. Image 1 • Synthesized a novel composite single ion conductor gel polymer electrolyte. • High ionic conductivity of 2.8 × 10−5 S/cm at 25 °C, high LTN of 0.75 and stable cycle performance at 25 °C and 60 °C. • Molecular dynamic simulation was applied for Li ion coordination and diffusion information. [ABSTRACT FROM AUTHOR]