The Qingdao Energy Institute Has Published a Review on the Breakthrough in Regulating Multi-level Structures to Overcome the Charge Transmission Bottleneck in Solid-State Lithium Batteries.

Solid-state lithium metal batteries are regarded as the ideal choice for next-generation energy storage technologies due to their high energy density and excellent safety. However, the slow charge transfer kinetics within the solid components and across the components severely limit their actual energy density, rate performance, and cycle life. Therefore, revealing the intrinsic relationship between "structure - charge transport - performance" and improving the charge transfer kinetics of heterogeneous solid-state systems through structural regulation have become the key to promoting the practical application of solid-state batteries.

Recently, the Solid-State Energy Systems Technology Center of Qingdao Energy Institute systematically reviewed the research progress in the regulation of the three-level structures (electrode, electrolyte, and battery) of solid-state lithium batteries. It deeply analyzed the key influencing factors and regulatory principles of each level structure regulation, and comprehensively evaluated and compared the gain effects and limitations of various structural optimization strategies in improving ion transmission. Finally, it envisioned the multi-level structure regulation paths for achieving rapid charge transmission dynamics in the future, providing widely applicable design principles for the development of next-generation high-performance inorganic solid-state lithium metal batteries.

For composite cathodes, the proportions of active materials, solid electrolytes, conductive agents, and binders can be precisely controlled through component engineering to construct a continuous and efficient ion/electron transmission network. This ensures efficient transmission while maximizing the mass of active materials. Through size engineering, the particle sizes and proportions of active materials and solid electrolytes can be optimized to shorten the charge transmission path. Gradient design can actively match the lithium ion flux distribution in thick electrodes, thereby synergistically increasing the loading and utilization rate of active materials.

In the field of solid electrolytes, the structural control strategies cover two major systems: inorganic solid electrolytes and composite solid electrolytes. For inorganic solid electrolytes, multi-scale collaborative optimization from micro-scale doping, defect regulation to macro-scale densification processes is required to ensure rapid lithium ion migration. For composite solid electrolytes, the advantages of organic-inorganic materials are complemented, and the filler structure design ranging from zero-dimensional particles to three-dimensional frameworks is combined to achieve a significant increase in ionic conductivity.

The optimization and design of the overall structure of the battery are equally crucial. The thinning of the electrolyte layer can significantly reduce the resistance of ion transmission, which is a key path to achieving high energy density and high rate capability of the battery; introducing a buffer layer, electrolyte penetration, and multi-layer electrolyte design can effectively improve the lithium ion transmission at the interface; the three-dimensional integration of the electrode/ electrolyte can significantly increase the interface contact area and shorten the ion migration path, thereby achieving efficient synergy between charge transmission and electrochemical reactions.

Looking ahead, structural regulation will evolve in four main directions:

1. Integrating machine learning with multi-physics field modeling, shifting from single-factor analysis to multi-scale structural collaborative design;

2. Systematically revealing the quantitative relationships between key parameters of electrode structures, transmission characteristics, and battery performance indicators, and establishing quantitative design guidelines for high-load electrodes;

3. Innovating the research paradigm for practical solid electrolytes, combining high-throughput computing to solve problems such as material system development of ultra-thin electrolyte membranes, solvent selection, and rheological regulation of slurry;

4. Establishing a quantitative evaluation system for the compatibility of electrode and solid electrolyte interfaces, achieving the transition from qualitative analysis to quantitative analysis.

Original link:

https://pubs.rsc.org/en/Content/ArticleLanding/2025/CS/D5CS00895F