Recent progress and perspectives on designing high-performance thick electrodes for all-solid-state lithium batteries

All-solid-state lithium batteries (ASSLBs) with higher energy density and improved safety have been regarded as an alternative to the state-of-the-art Li-ion batteries. As a critical component of the battery, the active materials are stored in the cathode, which directly determines the capacity and energy density output. Increasing the thickness of the electrodes can raise the ratio of active materials in the packaged cell, thus showing the potential to achieve higher energy densities. However, the development of thickness-based ASSLBs is still hindered by the sluggish electrochemical kinetics caused by the slow Li+/e− transport in the high-tortuosity channels/pathways. In this review, we comprehensively summarize the recent progress in the emerging area of thick electrodes to solve the critical issue and develop high-performance ASSLBs. Firstly, we overview the recent developments in the design of thick electrodes with continuous Li+/e− transport pathways and low-tortuosity structures. After that, the interfacial engineering on creating a favorable SSE/electrode material interface is reviewed. Subsequently, several factors such as particle size, binder, crystal structure and solvent that have a great influence on building Li+/e− transport pathways are discussed. Moreover, the improvement of intrinsic electrochemical kinetics via high-conductivity electrode design is introduced. Lastly, the recent development of thick electrode-based ASSLB pouch cells are summarized, and the future directions of thick electrodes in ASSLBs are speculated upon.