Inorganic solid electrolytes (SEs) possess substantial safety and electrochemical stability, which make them as key components of safe rechargeable solid-state Li batteries with high energy density. However, complicated integrally molding process and poor wettability between SEs and active materials are the most challenging barriers for the application of SEs. In this regard, we explore composite SEs of the active ceramic LiAlGe(PO) (LAGP) as the main medium for ion conduction and the polymer P(VDF-HFP) as a matrix. Meanwhile, for the first time, we choice high chemical, thermal, and electrochemical stability of ionic liquid swelled in polymer, which significantly ameliorate the interface in the cell. In addition, a reduced crystallinity degree of the polymer in the electrolyte can also be achieved. All of these lead to good ionic conductivity of the composite electrolyte (LPELCE), at the same time, good compatibility with the lithium electrode. Especially, high mechanical strength and stable solid electrolyte interphase which suppressed the growth of lithium dendrites and high thermal safety stability can also be observed. For further illustration, the solid-state lithium battery of LiFePO/LPELCE/Li shows relatively satisfactory performance, indicating the promising potentials of using this type of electrolyte to develop high safety and high energy density solid-state lithium batteries.

Recently, poor security in conventional liquid electrolytes and high interfacial resistance at the electrode/electrolyte interface are the most challenging barriers for the expanded application of lithium batteries. In this regard, easy processing and flexible composite ionic liquid gel polymer electrolytes (ILGPEs) supported by Li1.5Al0.5­Ge1.5­(PO4)3 (LAGP) are fabricated and investigated. The electrolyte is effectively combined with good electrochemical performances and thermal safety. Among these, the effects of different types of fillers such as the inert filler-SiO2 and the active filler-LAGP on the ionic conductivity were studied in detail. LAGP particles can not only effectively reduce the crystallinity of the polymer matrix but also provide lithium ions and act as the lithium-ion conductor leading to higher ionic conductivity and Li+ ion transference number. Especially, the electrolyte shows good compatibility and no dendrite with the Li metal anode, significantly improving cyclic stability of LiFe­PO4/Li batteries. The results indicate that the ILGPE-10%LAGP is a potential alternative electrolyte for high safety rechargeable solid-state lithium metal batteries.

Despite their high theoretical energy density, lithium-sulfur (Li-S) batteries are hindered by practical challenges including sluggish conversion kinetics and shuttle effect of polysulfides. Here, a nitrogen-doped continuous porous carbon (CPC) host anchoring monodispersed sub-10 nm FeS 2 nanoclusters (CPC@FeS 2 ) is reported as an efficient catalytic matrix for sulfur cathode. This host shows strong adsorption of polysulfides, promising the inhibition of polysulfide shuttle and the promoted initial stage of catalytic conversion process. Moreover, fast lithium ion (Li-ion) diffusion and accelerated solid-solid conversion kinetics of Li 2 S 2 to Li 2 S on CPC@FeS 2 host guarantee boosted electrochemical kinetics for conversion process of sulfur species in Li-S cell, which gives a high utilization of sulfur under practical conditions of high loading and low electrolyte/sulfur (E/S) ratio. Therefore, the surfur cathode (S/CPC@FeS 2 ) delivers a high specific capacity of 1459 mAh g −1 at 0.1 C, a stable cycling over 900 cycles with ultralow fading rate of 0.043% per cycle, and an enhanced rate capability compared with cathode only using carbon host. Further demonstration of this cathode in Li-S pouch cell shows a practical energy density of 372 Wh kg −1 with a sulfur loading of 7.1 mg cm −2 and an E/S ratio of 4 µL mg −1 .

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