LAUSR

The development of all-solid-state technology involvingLi-free transition-metalbased cathodes and Li-metal anodes has become an emerging trend with regard to solving the energy and safety bottleneck of current Li-ion batteries [1,2]. Although relevant publications in this area have increased in recent years, most of them have focused on developing solidstate electrolytes and reviving Li-metal anodes, whereas much less attention has been paid to the customization of cathodes, which determine the overall cell energy density. Intercalation-type Li-free cathodes storing guest ions in topotactic manners can effectively avoid drastic changes in micro/macrostructures and physical properties, achieving generally strong reversibility during the electrochemical process [3–5]. Exploring intercalationtype Li-free cathodes is expected to solve the long-standing open problem of large interfacial resistance between solid-state electrolytes and cathodes from the electrode design perspective. More importantly, it can also address concerns over raw material availability in Li-ion battery production [6]. Specifically, commercial cathodes suitable for large-scale energy storage applications (e.g. electric vehicles) that demonstrate high energy density and a long lifetime are highly reliant on Co or Ni, which is concerning owing to their high cost, scarcity and centralized/volatile supply chains. Therefore, the development and commercialization of Li-free cathodes without Co/Ni is critical for both the all-solid-state and traditional Li-ion battery industries. Figure 1. (A–C) Establishing a theoretical framework for quantitatively regulating voltage and phase stability competition based on a p-type alloying strategy combined with two improved ligand-field descriptors ( CFSS α−β and CFSEα−β). Reprinted with permission from ref. [9].