In Situ Interphase Engineering for beyond Lithium-Ion Battery Technologies

The pressing need to circumvent the negative impact of human activities on the environment has escalated the demand for electrochemical energy storage devices with an ever-growing energy density. Among the technologies, metal–sulfur and metal–air batteries appear to be promising owing to (i) less dependence on rare metals such as electrode materials, (ii) low carbon emission, and (iii) energy density on par with that of combustion engines. Nevertheless, the cycling stability of metal–air batteries is yet inferior due to parasitic reactions at both the cathode and anode interphases. Herein, the interphase modification and engineering beyond lithium-ion technologies were discussed, with a focus on in situ approaches. In situ interphase engineering could be facilitated through additives with no extra coating/deposition step, where the interphases formed are mostly thermodynamically stable. The research gaps on cathode–electrolyte interphases (CEI) for the sulfur cathode and air cathode are identified, highlighting the future research directions to achieve a balanced performance between the cathode and the metal anode.