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All‐solid‐state lithium batteries (ASSBs) enabled by solid‐state electrolytes (SEs) including oxide‐based and sulfide‐based electrolytes have gained worldwide attention because of their intrinsic safety and higher energy density over conventional lithium‐ion batteries (LIBs). However, despite the high ionic conductivity of advanced SEs, ASSBs still exhibit high overall internal resistance, the most significant contributor of which can be ascribed to the cathode‐SE interfaces. This review seeks to clarify the critical issues regarding the cathode‐SE interfaces, including fundamental principles and corresponding solutions. First, major issues concerning electro‐chemo‐mechanical instability between cathodes and SEs and their formation mechanisms are discussed. Then, specific problems in oxides and sulfides and various solutions and strategies toward interfacial modifications are highlighted. Efforts toward the characterization and analysis of cathode‐SE interfaces with advanced techniques are also summarized. Finally, perspectives are offered on several problems demanding urgent solutions and the future development of SE applications and ASSBs. [ABSTRACT FROM AUTHOR]

The electrochemical stability window of the electrolyte solution limits the energy content of non-aqueous lithium metal batteries. In particular, although electrolytes comprising fluorinated solvents show good oxidation stability against high-voltage positive electrode active materials such as LiNi0.8Co0.1Mn0.1O2 (NCM811), the ionic conductivity is adversely affected and, thus, the battery cycling performance at high current rates and low temperatures. To address these issues, here we report the design and synthesis of a monofluoride ether as an electrolyte solvent with Li-F and Li-O tridentate coordination chemistries. The monofluoro substituent (-CH2F) in the solvent molecule, differently from the difluoro (-CHF2) and trifluoro (-CF3) counterparts, improves the electrolyte ionic conductivity without narrowing the oxidation stability. Indeed, the electrolyte solution with the monofluoride ether solvent demonstrates good compatibility with positive and negative electrodes in a wide range of temperatures (i.e., from −60 °C to +60 °C) and at high charge/discharge rates (e.g., at 17.5 mA cm−2). Using this electrolyte solution, we assemble and test a 320 mAh Li||NCM811 multi-layer pouch cell, which delivers a specific energy of 426 Wh kg−1 (based on the weight of the entire cell) and capacity retention of 80% after 200 cycles at 0.8/8 mA cm−2 charge/discharge rate and 30 °C. The energy content of non-aqueous lithium batteries is limited by the electrochemical stability window of the electrolyte solution. Here, the authors report a monofluoride ether-based electrolyte to stabilize high-voltage lithium metal batteries at high current rates and low temperatures. [ABSTRACT FROM AUTHOR]

As a promising candidate of current solid-state electrolytes with various advantages, such as broad electrochemical stability window, high thermal stability, and chemical stability, garnet-type solid-state electrolyte Li7La3Zr2O12 (LLZO) attracts extensive research attention. Researchers usually use the element doping method to improve the lithium ion conductivity of LLZO and to stabilize the cubic phase. However, the improvements either increase the cost of raw materials or need complex process. In this work, the preparation process of Al-doped LLZO is optimized by a simple post-doping method (LLZO-Al), and the as-prepared LLZO-Al shows a high lithium ion conductivity of 5.331 × 10−4 S cm−1 and an activation energy of 0.25 eV at room temperature. In addition, the LLZO-Al exhibits excellent stability against Li in LiǁLLZO-AlǁLi symmetric cell, and the LiNi0.8Co0.1Mn0.1O2 (NCM811)ǁLLZO-AlǁLi solid-state cell delivers a stable cycle of 120 cycles at 0.1C. This work offers a low-cost preparation method of LLZO-based solid-state electrolytes with high ionic conductivities for high-energy solid-state lithium metal batteries. [ABSTRACT FROM AUTHOR]

Solid polymer electrolyte with good thermal stability and flexibility is an excellent candidate for solid‐state lithium metal batteries, while its low ionic conductivity caused by high crystallinity limits its application at ambient temperature. Here a metal organic framework (zeolitic imidazolate framework‐8, ZIF‐8) composited comb‐like methoxy poly(ethylene glycol) acrylate polymer electrolyte (MCPE) with high ionic conductivity (9.96 × 10−5 S cm−1 at 30 °C) is prepared by an in situ UV polymerization method. The as‐prepared MCPE exhibits improved mechanical property due to the introduction of porous ZIF‐8 nanofillers, which is beneficial to suppress the growth of lithium dendrites. Consequently, the LiFePO4||MCPE||Li cells show a high capacity of 116 mAh g−1 at 30 °C and 0.5 C, and maintain 89.4% of initial capacity after 150 cycles with the average Coulombic efficiency of 99.9%. These results demonstrate that the MCPE shows great potential in solid‐state lithium metal batteries near room temperature. [ABSTRACT FROM AUTHOR]

Although silicon (Si) anode has extremely high specific capacity, the damage to the electrode caused by the huge volume expansion greatly hinders its practical application in lithium-ion batteries. Aiming to alleviate this problem, a high-performance aqueous binder (AMNG) with gradient hydrogen bonding and flexible three-dimensional network structure is prepared by a one-pot method. Compared to the conventional linear polyacrylic acid (PAA) binder, the AMNG binder exhibits enhanced ionic conductivity and stress dissipation for Si nanoparticles, which is able to greatly reduce the side reactions caused by volume changes and considerably improve the electrochemical performance of Si anodes. As a result, the Si nanoparticles using the AMNG binder exhibit an initial discharge capacity as high as 3101 mAh g−1 with a Coulombic efficiency of 89.95%, and a capacity retention of 71.6% for 120 cycles, which are superior to the electrode using PAA, corresponding to 2832 mAh g−1, 88.37% and 28.1%, respectively. More prominently, the practical application of the AMNG binder is evaluated in high-mass-loading Si-based electrodes and even in full cells with LiFePO 4 , all showing satisfied performance. Therefore, this design approach is valuable as a reference for the preparation of commercial aqueous binders. [Display omitted] • An environmentally friendly binder is prepared by an aqueous one-pot method. • The binder embodies "gradient hydrogen bonding" and "elastic 3D network". • Nitrile groups and ether bonds boost the ionic conductivity of the binder. • The binder is universal for practical application of Si-based anodes. [ABSTRACT FROM AUTHOR]

Abstract The development of facile, inexpensive and large-scale methods to prepare carbon scaffolds with high sulfur content is crucial to the practical applications of Li-S Battery. Herein, Nitrogen, Oxygen and Cobalt multiple-doped graphitized mesoporous carbon sulfur composites (N-O-Co-C/S) with high sulfur content (90%) are developed via inexpensive carbonization methods. The composites exhibit superior performance with a capacity of 610 mAh g−1 at a current of 0.5 C after 200 cycles and 302 mAh g−1 at a current of 2 C after 1400 cycles. The superior performance of N-O-Co-C/S composites can be attributed to the enhanced electrical conductivity and ionic conductivity of Co-N-O-C/S composites, which can be supported by electrochemical impedance spectroscopy measurement. The polysulfide-trapping was mainly attributed to the strong O-S, N-S and Co-S interactions, thus improving the e electrochemical performance. Highlights • Nitrogen, Oxygen and Cobalt multiple-doped mesoporous graphitized carbon are been synthesized. • Its composites with sulfur show excellent electrochemical performances. • N and Co co-doped graphitized carbon can facilitate charge transfer and suppress the shuttle phenomenon. [ABSTRACT FROM AUTHOR]

Nano-sized fillers in a polymer matrix with good distribution can play a positive role in improving polymer electrolytes in the aspects of ionic conductivity, mechanical property and electrochemical performance of Li-ion cells. Herein, polyethylene oxide (PEO)/Li 3 PS 4 hybrid polymer electrolyte is prepared via a new in-situ approach. The ionic conductivities of the novel hybrid electrolytes with variable proportions are measured, and the optimal electrolyte of PEO-2%vol Li 3 PS 4 presents a considerable ionic conductivity of 8.01 × 10 −4  S cm −1 at 60 °C and an electrochemical window up to 5.1 V. The tests of DSC and EDXS reveal that the Li 3 PS 4 nanoparticles with better distribution, as active fillers scattering in the PEO, exhibit a positive effect on the transference of lithium ion and electrochemical interfacial stabilities. Finally, the assembled solid-state LiFePO 4 /Li battery presents a decent cycling performance (80.9% retention rate after 325 cycles at 60 °C) and excellent rate capacities with 153, 143, 139 and 127 mAh g −1 at the discharging rate of 0.1 C, 0.2 C, 0.5 C and 1 C at 60 °C. It is fully proved that it is an advanced strategy to preparing the new organic/inorganic hybrid electrolytes for lithium-ion batteries applications. [ABSTRACT FROM AUTHOR]

A catalytic material is introduced into the polymer matrix to prepare a novel polymeric alkaline electrolyte membrane (AEM) which simultaneously increases ionic conductivity, reduces the fuel cross-over. In this work, the hydroxide anion exchange membrane is mainly composed of poly(vinylalcohol) and alkaline exchange resin. CoCl 2 is added into the poly(vinylalcohol) and alkaline exchange resin gel before casting the membrane to introduce catalytic materials. CoCl 2 is converted into CoOOH after the reaction with KOH solution. The crystallinity of the polymer matrix decreases and the ionic conductivity of the composite membrane is notably improved by the introduction of Co-species. A direct borohydride fuel cell using the composite membrane exhibits an open circuit voltage of 1.11 V at 30 °C, which is notably higher than that of cells using other AEMs. The cell using the composite membrane achieves a maximum power density of 283 mW cm −2 at 60 °C while the cell using the membrane without Co-species only reaches 117 mW cm −2 at the same conditions. The outstanding performance of the cell using the composite membrane benefits from impregnation of the catalytic Co-species in the membrane, which not only increases the ionic conductivity but also reduces electrode polarization thus improves the fuel cell performance. This work provides a new approach to develop high-performance fuel cells through adding catalysts in the electrolyte membrane. [ABSTRACT FROM AUTHOR]

• Flexible solid-state cells are developed with an in situ integration strategy. • A 20-µm-thick hybrid polymer/ceramic/ionic liquid electrolyte is prepared. • Stable interfaces are built, keeping intimate contact and reducing resistance. • The Li 4 Ti 5 O 12 /LiNi 0.8 Co 0.1 Mn 0.1 O 2 cell exhibits long cycling life at 30 °C. • The use of Si-based anode achieves 489.6 Wh kg−1 energy density at material's level. Flexible solid-state batteries (FSSBs) are indispensable energy storage devices to fulfil the energy and safety requirements for future flexible applications. The bottlenecks of FSSBs are how to realize high energy density with competent ionic conductivity for room-temperature (RT) flexible applications. Here, the first fabrication of RT FSSB with high energy density is reported, which is realized by in situ integration of a 20-µm-thick hybrid polymer/ceramic/ionic liquid solid-state electrolyte (SSE) between the high energy combination of anode/cathode electrodes. The in situ electrode/electrolyte interfacial integration strategy provides an ultrathin SSE layer, ultralow resistance and superior flexibility, and the SSE guarantees both high ionic conductivity and good compatibility with high-energy cathode LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811). The fabricated Li 4 Ti 5 O 12 /NCM811 FSSB delivers super-low resistance approaching conventional liquid cells and excellent cycling stability up to 600 cycles at RT. The extension of anode to SiO x @graphite leads to a high theoretical energy density of 489.6 Wh kg−1 at material's level, times higher than current options. In addition, the RT FSSB shows great flexibility, indicating a high performance application in future flexible electronics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zeolitic imidazolate framework-90 grafted with ionic liquid (ZIF-90-g-IL) was prepared. • Solid polymer electrolytes (SPEs) with ZIF-90-g-IL were obtained. • Composite SPEs showed high ionic conductivity and broad electrochemical stability window. • Composite SPEs could inhibit growth of lithium dendrites. • Li batteries with composite SPEs exhibited super-long cycle life at high rate. The stable structure, high porosity and surface functionality endow metal organic frameworks (MOFs) nanoparticles as excellent nanofillers for high-performance poly (ethyleneoxide)-based solid polymer electrolytes (PEO SPEs). However, the agglomeration of MOFs severely limits their potential applications. Herein, a novel zeolitic imidazolate framework-90 nanofiller grafted with imidazole ionic liquid containing siloxane groups (ZIF-90-g-IL) is prepared by dehydration condensation reaction, which enables the uniform distribution of the nanofiller in PEO SPEs. The resulting composite PEO SPE with ZIF-90-g-IL nanofillers delivers higher ionic conductivity of 1.17 × 10-4 S/cm at 30 °C and lithium ion transference number of 0.44, wider electrochemical stability window of 4.8 V, and stronger ability to inhibit lithium dendrite growth than the PEO SPE with unmodified ZIF-90. The strong interaction of ZIF-90-g-IL with PEO is caused by the chelation of quaternary ammonium cations of ionic liquid groups on the ZIF-90-g-IL surface with oxygen containing a lone pair of electrons of PEO, resulting in a uniform distribution of the nanofillers in PEO. The LFP||Li half cells with the PEO/ZIF-90-g-IL SPE exhibit good cycling performance with 71% capacity retention (101 mAh g−1) after 500 cycles at 2C under 60 °C, and show excellent cycling performance with 97.4% capacity retention (148 mAh g−1) after 30 cycles at 0.1C under 30 °C. The composite SPE is also used for high-voltage NCM811||Li half cells. The capacity retention is 63% (99 mAh g−1) after 100 cycles at 0.1C under 60 °C. The results imply ZIF-90-g-IL as effective nanofillers for SPEs showing a great potential application in all solid-state lithium metal batteries. [ABSTRACT FROM AUTHOR]