Solid composite electrolytes (SCEs) that combine the advantages of solid polymer electrolytes (SPEs) and inorganic ceramic electrolytes (ICEs) present acceptable ionic conductivity, high mechanical strength, and favorable interfacial contact with electrodes, which greatly improve the electrochemical performance of all‐solid‐state batteries compared to single SPEs and ICEs. However, there are many challenges to overcome before the practical application of SCEs, including the low ionic conductivity less than 10−3 S cm−1 at ambient temperature, poor interfacial stability, and high interfacial resistance, which greatly restrict the room temperature performance. Herein, the advances of SCEs applied in all‐solid‐state lithium batteries are presented, including the Li ion migration mechanism of SCEs, the strategies to enhance the ionic conductivity of SCEs by various morphologies of ICEs, and construction methods of the low resistance and stable interfaces of SCEs with both cathode and anode. Finally, some typical applications of SCEs in lithium batteries are summarized and future development directions are prospected. This work presents how it is quite significant to further enhance the ionic conductivity of SCEs by developing the novel SPEs with the special morphology of ICEs for advanced all‐solid‐state lithium batteries.

All-solid-state lithium metal battery is the most promising next-generation energy storage device. However, the low ionic conductivity of solid electrolytes and high interfacial impedance with electrode are the main factors to limit the development of all-solid-state batteries. In this work, a low resistance-integrated all-solid-state battery is designed with excellent electrochemical performance that applies the polyethylene oxide (PEO) with lithium bis(trifluoromethylsulphonyl)imide as both binder of cathode and matrix of composite electrolyte embedded with Li 7 La 3 Zr 2 O 12 (LLZO) nanowires (PLLN). The PEO in cathode and PLLN are fused at high temperature to form an integrated all-solid-state battery structure, which effectively strengthens the interface compatibility and stability between cathode and PLLN to guarantee high efficient ion transportation during long cycling. The LLZO nanowires uniformly distributed in PLLN can increase the ionic conductivity and mechanical strength of composite electrolyte efficiently, which induces the uniform deposition of lithium metal, thereby suppressing the lithium dendrite growth. The Li symmetric cells using PLLN can stably cycle for 1000 h without short circuit at 60 °C. The integrated LiFePO 4 /PLLN/Li batteries show excellent cycling stability at both 60 and 45 °C. The study proposed a novel and robust battery structure with outstanding electrochemical properties.

Due to high energy density, low cost, and nontoxicity, lithium-sulfur (Li-S) batteries are considered as the most promising candidate to satisfy the requirement from the accelerated development of electric vehicles. However, Li-S batteries are subjected to lithium polysulfides (LiPSs) shuttling due to their high dissolution in liquid electrolyte, resulting in low columbic efficiency and poor cycling performance. Moreover, the Li metal as an indispensable anode of Li-S batteries shows serious safety issues derived from the lithium dendrite formation. The replacement of liquid electrolytes with solid-state electrolytes (SSEs) has been recognized as a fundamental approach to effectively address above problems. In this review, the progress on applying various classes of SSEs including gel, solid-state polymer, ceramic, and composite electrolytes to solve the issues of Li-S batteries is summarized. The specific capacity of Li-S batteries is effectively improved due to the suppression of LiPSs shuttling by SSEs, while the rate and cycling performance remain relatively poor owing to the limited ionic conductivity and high interfacial resistance. Designing smart electrode/electrolyte integrated architectures, enabling the high ionic transportation pathway and compatible electrode/electrolyte interface, may be an effective way to achieve high performance solid-state Li-S batteries. and strategies have been attempted to address the above main issues of Li-S batteries, including using sulfur host materials, [4] unique separators [5] and interlayer, [6] composite of electrolyte, [7] novel binders, [8] etc. However, these approaches can only solve problems to a certain extent. Some review papers have concluded and commented on above potential solutions. [9] Recently, solid-state electrolytes (SSEs) including gel, solid-state polymer, ceramic, and composite electrolytes are attracting increasing interest for application in Li-S batteries to fundamentally solve the issues of Li-S batteries caused by liquid electrolyte. Furthermore, nonflammable solid electrolytes would improve the safety performance of Li-S batteries remarkably. In the past few years, more and more research work focused on applying SSEs in Li-S batteries to solve the LiPSs dissolution. [10] Some review papers about Li-S batteries have also emphasized the significance of SSEs. However, until now, there are few review papers specially summarizing the progress and prospect of the solid-state Li-S batteries.This review aims to provide an overview of SSEs for addressing the major drawbacks of Li-S batteries, including the electrochemical reaction process of S cathode and its corresponding problems as well as traditional solutions, the recent research progress of solid-state Li-S batteries using gel, solidstate polymer, ceramic, and composite electrolytes, and strategies for overcoming the deficiencies of solid-state electrolytes such as low room-temperature ionic conductivity and high Solid-State Electrolytes interfacial resistance. In addtition, the mechanism a...