Structure Design of Cathode Electrodes for Solid‐State Batteries: Challenges and Progress

Solid‐state lithium batteries have aroused wide interest with the probability to guarantee safety and high energy density at the same time. In the past decade, fruitful endeavors have been devoted to promoting each component of these batteries, including solid electrolyte with high conductivity, dendrite‐free lithium anode, and high‐capacity cathode. However, the currently achieved cell performances are still inconsistent with the original expectations, in which interfaces severely hamper the energy output and cycling stability for practical application. Herein, particular attentions are paid to the interface between cathode and solid electrolyte. The huge resistance caused at this interface can be found throughout the entire life of batteries from preparation to operation. Accordingly, these issues are divided into physical contact, thermal interdiffusion, space‐charge layer, electrochemomechanical breakdown, and undesirable side reactions and further elucidated in detail. Moreover, representative developments concerning the cathode/solid electrolyte interface in terms of compositional and morphological control in cathode, architecture and manufacture design in solid electrolyte, and artificial interphase building are summarized. With these efforts, the emphasis of the fundamental issues and perspectives of interface between cathode and solid electrolyte may eventually contribute to high‐energy long‐cycling solid‐state lithium batteries.