Ion Hopping: Design Principles for Strategies to Improve Ionic Conductivity for Inorganic Solid Electrolytes

Solid electrolyte has been considered as an ideal substitution of liquid electrolyte, by avoiding the potential hazards of volatilization, flammability and explosion for liquid electrolyte based rechargeable batteries. However, there are significant performance gaps to be bridged between solid electrolytes with liquid electrolytes, one with the particular importance is the ionic conductivity which is highly dependent on the material types and structures. In this review, we re-visit the general physical image of ion hopping in the crystalline structure, by highlighting two main kernels that impact ion migration: ion hopping pathways and skeletons interaction. We then systematically summarize the universal strategies to effectively improve ionic conductivity of inorganic solid electrolytes: (1) constructing rapid diffusion pathways for mobile ions; (2) reducing resistance of the surrounding potential field. The scoped strategies offer an exclusive view on the working principle of ions movements regardless of the ion species, thus providing a comprehensive guidance for the future exploitation of solid electrolytes.