Solid-state batteries (SSBs) have recently been revived to increase the energy density and eliminate safety concerns associated with conventional Li-ion batteries with flammable liquid electrolytes. To achieve large-scale, low-cost production of SSBs as soon as possible, it would be advantageous to modify the mature manufacturing platform, involving slurry casting and roll-to-roll technologies, used for conventional Li-ion batteries for application to SSBs. However, the manufacturing of SSBs depends on the development of suitable solid electrolytes. Inorganic–polymer composite electrolytes combine the advantages of inorganic and polymer solid electrolytes, making them particularly suitable for the mass production of SSBs. In this Review, we discuss the properties of solid electrolytes comprising inorganic–polymer composites and outline the design of composite electrolytes for realizing high-performance devices. We also assess the challenges of integrating the composite electrolytes into batteries, which will enable the mass production of SSBs. Inorganic–polymer composites have emerged as viable solid electrolytes for the mass production of solid-state batteries. In this Review, we examine the properties and design of inorganic–polymer composite electrolytes, discuss the processing technologies for multilayer and multiphase composite structures, and outline the challenges of integrating composite electrolytes into solid-state batteries.

Tailoring inorganic–polymer composites for the mass production of solid-state batteries

Porous film host-derived 3D composite polymer electrolyte for high-voltage solid state lithium batteries

Rechargeable batteries with lithium metal anodes exhibit higher energy densities than conventional lithium-ion batteries. Solid-state electrolytes (SSEs) provide the opportunity to unlock the full potential of lithium metal anodes and fundamentally eliminate safety concerns caused by flammable liquid electrolytes. Up to now, most studies on SSEs have been focused on enhancing the ionic conductivity and improving the interfacial stability. However, the electrolyte thickness, which has received less attention, also plays an important role in determining the energy density and electrochemical performance of all-solid-state lithium batteries (ASSLBs). Recognizing this, our review evaluates SSE studies beyond traditional factors and focuses on a thickness perspective. We systematically analyze the influence of the electrolyte thickness on the energy densities of ASSLB pouch cells, and highlight the strategies that dramatically reduce the thickness of SSE membranes without sacrificing their mechanical properties. Then, we discuss recent advances and challenges of ASSLBs based on high-voltage and high-capacity cathodes, as well as novel configurations such as bipolar and flexible ASSLBs. Finally, we provide perspectives and suggestions towards high energy-density ASSLBs for future commercialization.

Reducing the thickness of solid-state electrolyte membranes for high-energy lithium batteries

An ultrathin solid polymer electrolyte (SPE) consisting of modified polyethylene (PE) as the host and poly(ethylene glycol) methyl ether acrylate and lithium salts as fillers is presented. The porous poly(methyl methacrylate)-polystyrene interface layers closely attached on both sides of the PE effectively improve the interface compatibility among electrolytes and electrodes. The resultant 10 μm-thick SPEs possess an ultrahigh ionic conductance of 34.84 mS at room temperature and excellent mechanical properties of 103.0 MPa with elongation up to 142.3%. The Li//Li symmetric cell employing an optimized solid electrolyte can stably cycle more than 1500 h at 60 °C. Moreover, the LiFePO4 //Li pouch cell can stably cycle over 1000 cycles at 1 C rate and with a capacity retention of 76.4% from 148.9 to 113.7 mAh g-1 at 60 °C. The LiCoO2 //Li pouch cell can stably operate at 0.1 and 0.2 C rate for each 100 cycles. Furthermore, the LiFePO4 //Li pouch cell can work stably after curling and folding, which proves its excellent flexibility and safety simultaneously. This work offers a promising strategy to realize ultrathinness, excellent compatibility, high strength, as well as safe solid electrolytes for all-solid-state lithium-metal batteries.

10 μm-Thick High-Strength Solid Polymer Electrolytes with Excellent Interface Compatibility for Flexible All-Solid-State Lithium-Metal Batteries.

Reviewing the current status and development of polymer electrolytes for solid-state lithium batteries

Considerable efforts are devoted to relieve the critical lithium dendritic and volume change problems in the lithium metal anode. Constructing uniform Li+ distribution and lithium "host" are shown to be the most promising strategies to drive practical lithium metal anode development. Herein, a uniform Li nucleation/growth behavior in a confined nanospace is verified by constructing vertical graphene on a 3D commercial copper mesh. The difference of solid-electrolyte interphase (SEI) composition and lithium growth behavior in the confined nanospace is further demonstrated by in-depth X-ray photoelectron spectrometer (XPS) and line-scan energy dispersive X-ray spectroscopic (EDS) methods. As a result, a high Columbic efficiency of 97% beyond 250 cycles at a current density of 2 mA cm-2 and a prolonged lifespan of symmetrical cell (500 cycles at 5 mA cm-2 ) can be easily achieved. More meaningfully, the solid-state lithium metal cell paired with the composite lithium anode and LiNi0.5 Co0.2 Mn0.3 O2 (NCM) as the cathode also demonstrate reduced polarization and extended cycle. The present confined nanospace-derived hybrid anode can further promote the development of future all solid-state lithium metal batteries.

Early Lithium Plating Behavior in Confined Nanospace of 3D Lithiophilic Carbon Matrix for Stable Solid-State Lithium Metal Batteries.

Sandwich structured NASICON-type electrolyte matched with sulfurized polyacrylonitrile cathode for high performance solid-state lithium-sulfur batteries

Jiangkui Hu

Papers

Porous film host-derived 3D composite polymer electrolyte for high-voltage solid state lithium batteries

Early Lithium Plating Behavior in Confined Nanospace of 3D Lithiophilic Carbon Matrix for Stable Solid-State Lithium Metal Batteries.

Sandwich structured NASICON-type electrolyte matched with sulfurized polyacrylonitrile cathode for high performance solid-state lithium-sulfur batteries

Solid-state lithium metal batteries enabled with high loading composite cathode materials and ceramic-based composite electrolytes

Dry electrode technology, the rising star in solid-state battery industrialization