Developing high-safety Li-metal anodes (LMAs) is extremely important for the application of high-energy Li-metal batteries (LMBs), especially Li–S and Li–O₂ battery systems. However, the notorious Li-dendrite growth problem results in serious safety concerns for any energy storage application. Through a recent combination of interface-based science, nanotechnology-based solutions and characterization methods, the LMA is now primed for a technological boom. In this review, the recent emerging strategies and perspectives on LMAs are summarized, following which the current huge evolution in interfacial chemistry regulation, optimizing electrolyte components, designing a rational ‘host’ for lithium metal, optimizing “solid-state electrolytes” and other emerging strategies for developing high-safety LMAs is highlighted. Furthermore, several state-of-the-art in situ/operando synchrotron-based X-ray techniques for high safety LMB research are introduced. With the further development of LMAs in the future, subsequent application in high energy LMBs is to be expected.

For energy storage technologies, secondary batteries have the merits of environmental friendliness, long cyclic life, high energy conversion efficiency and so on, which are considered to be hopeful large-scale energy storage technologies. Among them, rechargeable lithium-ion batteries (LIBs) have been commercialized and occupied an important position as secondary batteries due to their high energy density and long cyclic life. Nevertheless, the uneven distribution of lithium resources and a large number of continuous consumptions result in a price increase for lithium. So, it is very crucial to seek and develop alternative batteries with abundant reserves and low cost. As one of the best substitutes for widely commercialized LIBs, sodium-ion batteries (SIBs) display gorgeous application prospects. However, further improvements in SIB performance are still needed in the aspects of energy/power densities, fast-charging capability and cyclic stability. Electrode materials locate at a central position of SIBs. In addition to electrode materials, electrolytes, conductive agents, binders and separators are imperative for practical SIBs. In this review, the latest progress and challenges of applications of SIBs are reviewed. Firstly, the anode and cathode materials for SIBs are symmetrically summarized from aspects of the design strategies and synthesis, electrochemical active sites, surrounding environments of active sites, reaction mechanisms and characterization methods. Secondly, the influences of electrolytes, conductive agents, binders and separators on the electrochemical performance are elucidated. Finally, the technical challenges are summarized, and the possible future research directions for overcoming the challenges are proposed for developing high performance SIBs for practical applications. Graphical abstract