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To realize high-energy-density Li metal batteries at low temperatures, a new electrolyte is needed to solve the high-voltage compatibility and fast lithium-ion de-solvation process. A gel polymer electrolyte with a small-molecular-weight polymer is widely investigated by combining the merits of a solid polymer electrolyte (SPE) and liquid electrolyte (LE). Herein, we present a new gel polymer electrolyte (P-DOL) by the lithium difluoro(oxalate)borate (LiDFOB)-initiated polymerization process using 1,3-dioxolane (DOL) as a monomer solvent. The P-DOL presents excellent ionic conductivity (1.12 × 10−4 S cm−1) at −20 °C, with an oxidation potential of 4.8 V. The Li‖LiCoO2 cell stably cycled at 4.3 V under room temperature, with a discharge capacity of 130 mAh g−1 at 0.5 C and a capacity retention rate of 86.4% after 50 cycles. Moreover, a high-Ni-content LiNi0.8Co0.1Mn0.1O2 (NCM811) cell can steadily run for 120 cycles at −20 °C, with a capacity retention of 88.4%. The underlying mechanism of high-voltage compatibility originates from the dense and robust B- and F-rich cathode interface layer (CEI) formed at the cathode interface. Our report will shed light on the real application of Li metal batteries under all-climate conditions in the future. [ABSTRACT FROM AUTHOR]

[Display omitted] The huge Li ion transport resistance through the grain boundaries (GBs) among rigid oxide particles forces the adoption of high-temperature sintering (HTS) process over 1000 °C. Nevertheless, the severe side reactions and uncontrollable lithium loss are always companied during the high-cost HTS process, which slows down the pace of oxide solid electrolyte (OSE) for practical application and accelerates the exploration of a new OSE sintering process. Herein, a near-room-temperature (60 °C) cold-sintering process is proposed by filling the GBs with a low-melting-point plastic crystal electrolyte (PCE). Due to the soft property and high-ionic conductivity of PCE, the Li ion transport rate through the GBs is 10 times faster than the bulk phase, endowing the OSE (Li 1.5 Al 0.5 Ge 1.5 (PO 4) 3 chosen as a representative) with a room temperature ionic conductivity of 0.25 mS cm−1. As proof of the concept, the assembled Li symmetrical cells perform a low over-potential of 50 mV with a capacity of 1 mA h cm−2 and full cells delivers a capacity retention of roughly 70% after 820 cycles (1.5 years) at 0.1C. [ABSTRACT FROM AUTHOR]

[Display omitted] Solid-state polymer electrolytes are outstanding candidates for next-generation lithium metal batteries in the realm of high specific energy densities, high safeties and tight contact with electrodes. However, their applications are still hindered by the limitations that no single polymer is electrochemically stable with the oxidizing high-voltage cathode and the highly reductive Li anode, simultaneously. Herein, a bilayer asymmetric polymer electrolyte (SL-SPE) without accessional interface resistance that using poly (ethylene glycol) diacrylate (PEGDA) as a "bridge" to connect the sulfonyl (O S = O)-contained oxidation-tolerated layer and polyether-derived reduction-tolerated layer (SPE), is proposed and synthesized by sequential two-step UV polymerizations. SL-SPE can provide widened electrochemical stability window up to 5 V, while simultaneously deploying a stable Janus interface property. Eventually, the superior high-voltage (4.4 V) cycling durability can be displayed in LiNi 0.6 Co 0.2 Mn 0.2 O 2 |SL-SPE|Li batteries. This finding provides a bran-new idea for designing multifunctional polymer electrolytes in the application of solid-state batteries. [ABSTRACT FROM AUTHOR]

In this paper, the microstructure and ionic conductivity of Li 1.5 Al 0.5 Ge 1.5 (PO 4) 3 (LAGP) solid electrolytes prepared by spark plasma sintering (SPS) were investigated by XRD, SEM, TEM and EIS, respectively. The results showed that as the sintering temperature was increased, both the relative density and the ionic conductivity of the sintered LAGP samples first increased and then decreased, achieving a maximum value of 97% and 2.12 × 10−4 S cm−1 simultaneously at 700 °C. At the same time, the crystallinity of the sintered samples was improved, while a few impurity phases, such as AlPO 4 and GeO 2 , appeared in the samples. It was also found that carbon contamination and oxycarbide gas was be brought in during SPS. Carbon contamination could produce an extra grain boundary impedance to the samples and could be removed by annealing at 500 °C in an air atmosphere. Oxycarbide gas could affect the relative density of the sintered LAGP samples and could be mitigated by choosing a suitable SPS process. Moreover, the shear modulus of the sintered LAGP was measured to be 49.6 GPa, which exceeded the minimum value of 8.5 GPa that was necessary to suppress Li dendrite growth. [ABSTRACT FROM AUTHOR]

Block copolymer electrolytes (BCPEs) are promising candidates for solid-state lithium battery applications because they can achieve improved mechanical performance and conductivity simultaneously. In this report, we report on fluorine-containing ABA triblock copolymer electrolytes (FBCPEs) with A blocks of perfluoroalkyl pendants and B blocks of poly(ethylene oxide) (PEO). It is found that fluorine-containing blocks endows considerable mechanical strength, high lithium ion transference number of t Li+ = 0.41, and wide electrochemical stability window up to 4.9 V to FBCPEs. In addition, FBCPEs can also participate in forming fluorinated solid electrolyte interphase (SEI), and thus serves to enhance the cycle stability of batteries. Combination of these excellent properties leads to the LiFePO 4 /FBCPEs/Li cells with excellent cycling performance and rate capability. The cycle results of the assembled LiNi 0.6 Co 0.2 Mn 0.2 O 2 /FBCPEs/Li cells indicate that FBCPEs have potential for application in high-voltage battery systems. [Display omitted] • Solid-state fluorine-containing triblock copolymer electrolytes were developed. • High lithium ion transference number and wide electrochemical stability window. • LiFePO 4 cells assembled with FBCPEs exhibit excellent cycling performances. [ABSTRACT FROM AUTHOR]

Sulfide-based composite solid-state electrolyte has been deemed as "Holy Grail" for unlocking solid-state lithium metal batteries (SSLMBs) with high-energy density, combining the extremely high ionic conductivity of sulfide and machinability of organic polymer. However, this appealing system is hitherto stymied by two hindrances, difficult to synthesize due to the chemical incompatibility of sulfide with moisture and polar solvents, moreover, interfacial instability with lithium (Li) anode inducing severe Li dendrite grown. Herein, by utilizing perfluoropolyethers as bifunctional adjuvant, we initiatively fabricate sulfide-based composite electrolyte, Poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/Li 10 GeP 2 S 12 and assemble SSLMBs. Perfluoropolyethers with low molecular weight facilitate the stable dispersion of Li 10 GeP 2 S 12 in casting solution, ascribed to their strong electronegativity of C–F bonds. In addition, high molecular weight perfluoropolyethers function as interfacial stabilizer, dramatically improving the interfacial compatibility with Li anode by in-situ forming a LiF-rich solid electrolyte interphase layer. This composite electrolyte exhibits high room temperature ionic conductivity (0.18 mS cm−1), outstanding lithium ion transfer number (0.68), good mechanical strength and nonflammability. The solid-state LiFePO 4 ǁLi battery presents superior long-term cycling stability and rate capability. Our study paves a new way for fabricating the sulfide-based composite electrolyte, provides an effective strategy for constructing compatible solid-state electrolyteǁLi interface. Image 1 • PVDF-HFP/Li 10 GeP 2 S 12 electrolyte is prepared by binary solution casting method. • PFPE 500 as dispersing solvents exhibit good chemical compatibility with Li 10 GeP 2 S 12. • A high ion conductivity (σ RT = 10−4 S cm−1) and Li+ transfer number (0.68) are obtained. • PFPEs as interfacial stabilizers enhance the compatibility of Li 10 GeP 2 S 12 with Li. • LiFePO 4 ‖Li battery shows good cycling stability and rate capability. [ABSTRACT FROM AUTHOR]