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Solid-state batteries (SSBs) are developed with the use of inflammable solid-state electrolytes to realize higher energy density and improved safety. However, the densification temperature of solid electrolytes via conventional sintering methods is usually high, especially for oxide-type electrolytes. Advanced sintering techniques such as spark plasma sintering have been developed to decrease the heat-treatment temperature and time. Recently, a novel cold sintering process (CSP) has been developed, which offers an alternative route to the densification of many solid-state electrolyte materials below 300 °C. Generally, the CSP involves multi-stage non-equilibrium processes such as dissolution-precipitation under external stress, viscous flow of saturated solutions and diffusion of species. Herein, the CSP application in different solid electrolytes and electrodes are summarized. It is expected that the CSP has great potential in preparing solid-state batteries and solid electrolytes in the future. [ABSTRACT FROM AUTHOR]

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] Polyvinylidene difluoride (PVDF) is one of the most attractive electrolyte materials for solid-state batteries due to its high ionic conductivity, however, the battery performance is limited by the high electrolyte–electrode interfacial resistance. Herein, PVDF polymer mixed with ceramic Li 7 La 3 Zr 2 O 12 is coated on cellulose support membrane (PLCSM) through a simple slurry-casting method. The ionic transport of PLCSM is originated from dimethyl formamide (DMF)-Li+ solvation structure, which plays a critical role in conducting lithium ions. β-PVDF after dehydrofluorination offers a high dielectric constant and enhances the dissociation of lithium salt. As a result, PLCSM with a total thickness of 85 µm presents an oxidation voltage of 4.9 V. Li-Li symmetric cells by employing PLCSM reveal that the critical current density (CCD) is increased to 1 mA cm−2. A full cell of LiFePO 4 |PLCSM |Li with high mass loading (1.2 mA h cm−2) shows a first-cycle discharge capacity of 160 mA h g−1. With LiNi 0.6 Mn 0.2 Co 0.2 O 2 as the cathode, the initial discharge capacity is 153 mA h g−1, and the capacity retention after 80 cycles is 80 %. The sandwiched PLCSM provides an effective strategy to achieve high-performance dendrite-free Li metal batteries. [ABSTRACT FROM AUTHOR]

A quasi-solid-state Li-Te battery was developed using a flexible gel polymer electrolyte and Te/C cathode. [Display omitted] A quasi-solid-state Li-Te battery is developed by using a flexible gel polymer electrolyte (GPE), porous carbon/tellurium cathode, and lithium metal anode. The ionic conductivity of GPE is controllable and reaches up to 8.0 × 10−4 S cm−1 at 25 °C. The good interfacial contact with Li metal ensures excellent cycling stability in Li/GPE/Li symmetric cells. Moreover, it is found that, compared to S and Se counterparts, the Li-Te battery exhibits good rate capability due to the high electrical conductivity of Te and excellent interfacial stability among GPE, Li, and Te. This work provides several facile strategies to develop safe and high-performance solid-state Li-Te batteries. [ABSTRACT FROM AUTHOR]

Substitution of liquid electrolyte with solid‐state electrolytes (SSEs) has emerged as a very urgent and challenging research area of rechargeable batteries. NASICON (Na3Zr2Si2PO12) is one of the most potential SSEs for Na‐ion batteries due to its high ionic conductivity and low thermal expansion. It is proven that the ionic conductivity of NASICON can be improved to 10−3 S cm−1 by Sc‐doping, of which the mechanism, however, has not been fully understood. Herein, a series of Na3+xScxZr2−xSi2PO12 (0 ≤x ≤ 0.5) SSEs are prepared. To gain a deep insight into the ion transportation mechanism, synchrotron‐based X‐ray absorption spectroscopy (XAS) is employed to characterize the electronic structure, and solid‐state nuclear magnetic resonance (SS‐NMR) is used to analyze the dynamics. In this study, Sc is successfully doped into Na3Zr2Si2PO12 to substitute Zr atoms. The redistribution of sodium ions at certain specific sites is proven to be critical for sodium ion movement. For x≤ 0.3, the promotion of sodium ion movement is attributed to sodium ion concentration increase at the Na2 sites and decrease at the Na1 and Na3 sites. For x> 0.3, the inhibition of sodium ion movement is due to the phase change from monoclinic to rhombohedral and an increasing impurity content. [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]

The low coulombic efficiency and poor cycle performance deriving from uncontrolled growth of dendrites have caused a serious obstacle to the practical application of lithium metal. Herein we propose a bifunctional regular-random dual cross-linking network solid polymer electrolyte (RRa-SPE) for dendrite-free all-solid-state lithium metal batteries. Under the synergistic effect of regular polymerization skeleton and random cross-linking network, the RRa-SPE effectively regulates the lithium deposition and facilitates the generation of a highly homogeneous and robust solid-electrolyte interphase (SEI) layer on lithium metal. Besides, this RRa-SPE shows benign ionic conductivity of 4.36 × 10−4 S cm−1 (at 30 °C), high lithium ion transference number of 0.76 and enhanced mechanical strength. The Li/RRa-SPE/Li symmetric cell maintains low and stable voltage polarization (0.15 V) after circulating for 1200 h at 0.5 mA cm−2. Improved LiFePO 4 /RRa-SPE/Li cell exhibits excellent rate capability and prominent cycle performance with a capacity retention of 99.6% after 240 cycles at 0.5 C at 30 °C. Image 1 The SPE is prepared via a facile UV-derived dual-reaction. With bifunctional network, the SPE effectively regulates the lithium deposition. The SPE shows enhanced ionic conductivity of 4.36 × 10−4 S cm−1 at 30 °C. The SPE exhibits high lithium ion transference number of 0.76. [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]