Lithium (Li) metal is considered as one of the most promising anode materials for next‐generation high‐energy‐density storage systems. However, the practical application of Li metal anode is hindered by interfacial instability and air instability due to the highly reactivity of Li metal. Unstable interface in Li metal batteries (LMBs) directly dictates Li dendrite growth, “dead Li” and low Coulombic efficiency, resulting in inferior electrochemical performance of LMBs and even safety issues. In addition, its sensitivity to ambient air leads to the severe corrosion of Li metal anode, high requirements of production and storage, and increased manufacturing cost. Plenty of efforts in recent years have overcome many bottlenecks in these fields and hastened the practical applications of high‐energy‐density LMBs. In this review, we focus on emerging methods of these two aspects to fulfill a stable and low cost electrode. In this perspective, design artificial solid electrolyte interphase (SEI) layers, construct three‐dimensional conductive current collectors, optimize electrolytes, employ solid‐state electrolytes, and modify separators are summarized to be propitious to ameliorate interfacial stability. Meanwhile, ex situ/in situ formed protective layers are highlighted in favor of heightening air stability. Finally, several possible directions for the future research on advanced Li metal anode are addressed.

Lithium (Li) metal is considered as a promising anode candidate for high-energy-density batteries. However, the high reactivity of Li metal leads to poor air stability, limiting its practical application. Additionally, the interfacial instability, such as dendrite growth and an unstable solid electrolyte interphase layer, further complicates its utilization. Herein, a dense lithium fluoride (LiF)-rich interfacial protective layer is constructed on the Li surface through a simple reaction between Li and fluoroethylene carbonate (denoted as LiF@Li). The LiF-rich interfacial protective layer consists of both organic (ROCO2Li and C–F-containing species, which only exist on the outer layer) and inorganic (LiF and Li2CO3, distribute throughout the layer) components with a thickness of ∼120 nm. Specifically, chemically stable LiF and Li2CO3 play an important role in blocking air and hence improve the air durability of LiF@Li anodes. Notably, LiF with high Li+ diffusivity facilitates uniform Li+ deposition, while organic components with high flexibility relieve volume change upon cycling, thereby enhancing the dendrite inhibition capacity of LiF@Li. Consequently, LiF@Li exhibits remarkable stability and excellent electrochemical performance in both symmetric cells and LiFePO4 full cells. Moreover, LiF@Li maintains its initial color and morphology even after air exposure for 30 min, and the air-exposed LiF@Li anode still retains its superior electrochemical performance, further establishing its outstanding air-defendable capability. This work proposes a facile approach in constructing air-stable and dendrite-free Li metal anodes toward reliable Li metal batteries.

For pursuing the ambitious goals in the burgeoning electric vehicles, portable electronic devices, and energy storage sectors, Li-ion batteries (LIBs) are considered as one of the most promising electrochemical power sources because of their high energy density and moderate cost. Particularly, the improvement of battery materials and recycling of spent LIBs are receiving great attention since the sustainable approaches for the synthesis, modification, and recycling of battery materials are the crucial factors to the successful large-scale implementation of LIBs. In this regard, supercritical carbon dioxide (SC-CO 2 ), which possesses many merits, such as environmentally friendly, low-cost, individual chemical environment, and especially its unique physical properties, has been employed as solvent and reaction medium in the synthesis and modification of diverse functional materials. In this review, we mainly aim at compiling the applications of SC-CO 2 technology in the synthesis and modification of electrode materials as well as the recycling of LIBs. First, the unique properties and principles of SC-CO 2 technology are highlighted. Second, the latest progresses of the electrode materials design and recycling with the assistance of SC-CO 2 technique are summarized. Finally, the challenges, future directions, and perspectives on the design and development of battery materials and battery recycling by SC-CO 2 technology are proposed.