Lithium metal anodes are potentially key for next-generation energy-dense batteries because of the extremely high capacity and the ultralow redox potential. However, notorious safety concerns of Li metal in liquid electrolytes have significantly retarded its commercialization: on one hand, lithium metal morphological instabilities (LMI) can cause cell shorting and even explosion; on the other hand, breaking of the grown Li arms induces the so-called "dead Li"; furthermore, the continuous consumption of the liquid electrolyte and cycleable lithium also shortens cell life. The research community has been seeking new strategies to protect Li metal anodes and significant progress has been made in the last decade. Here, an overview of the fundamental understandings of solid electrolyte interphase (SEI) formation, conceptual models, and advanced real-time characterizations of LMI are presented. Instructed by the conceptual models, strategies including increasing the donatable fluorine concentration (DFC) in liquid to enrich LiF component in SEI, increasing salt concentration (ionic strength) and sacrificial electrolyte additives, building artificial SEI to boost self-healing of natural SEI, and 3D electrode frameworks to reduce current density and delay Sand's extinction are summarized. Practical challenges in competing with graphite and silicon anodes are outlined.

Perovskites (ABX3) are promising oxygen evolution reaction (OER) catalysts for their highly intrinsic activity. The in‐depth understanding and the adjustment of dynamic reconstruction of active phases for perovskites in OER are still a daunting challenge. Here, a refined A‐site management strategy is proposed for perovskite oxides, which facilitates the surface reconstruction of the B‐site element based active phase to enhance the OER performance. Electrocatalyst LaNiO3 displays a dynamic reconstruction feature during OER with the growth of a self‐assembled NiOOH active layer, based on the in situ electrochemical Raman technology. Precise A‐site Ce doping lowers the reconstruction potential for the active phase and the dynamic structure–activity correlation is well established. Theoretical calculations demonstrate that A‐site Ce substitution upshifts the O 2p level for greater structural flexibility with optimized oxygen vacancy content, thereby activating the B‐site atom and promoting the active phase reconstruction. These results suggest that A‐site management prompts the B‐site element based active phase dynamic reconstruction via engineered X‐site content as a bridge. Therefore, indicating the strong correlation of each‐site component in perovskite oxides during OER and deepening the understanding of the fundamental processes of the structural transformation and further benefiting the accurate design of high‐efficiency perovskite OER electrocatalysts.

Tin foil should have outstanding volumetric capacity as a Li-ion battery anode; however, it suffers from an unacceptable initial coulombic efficiency (ICE) of 10-20%, which is much poorer than that of Si or SnO 2 nanoparticles. Herein, we demonstrate that bare Sn catalyzes liquid electrolyte decomposition at intermediate voltages to generate gas bubbles and Leidenfrost gas films, which hinder lithium-ion transport and erode the solid-electrolyte interphase (SEI) layer. By metallurgically pre-alloying Li to make Li x Sn foil, the lower initial anode potential simultaneously suppresses gassing and promotes the formation of an adherent passivating SEI. We developed a universally applicable roll-to-roll mechanical prelithiation method and successfully prelithiated Sn foil, Al foil and Si/C anodes. The as-prepared Li x Sn foil exhibited an increased ICE from 20% to 94% and achieved 200 stable cycles in LiFePO 4 //Li x Sn full cells at B2.65 mA h cm À2 . Surprisingly, the Li x Sn foil also exhibited excellent air-stability, and its cycling performance sustained slight loss after 12 h exposure to moist air. In addition to LiFePO 4 , the Li x Sn foil cycled well against a lithium nickel cobalt manganese oxide (NMC) cathode (4.3 V and B4-5 mA h cm À2 ). The volumetric capacity of the Li x Sn alloy in the LFP//Li x Sn pouch cell was up to B650 mA h cm À3 , which is significantly better than that of the graphite anode on a copper collector, with a rate capability as high as 3C. Broader contextSelf-supporting tin foil is a high-volumetric-capacity alternative to the graphite LIB anode; however, it shows an exceptionally low initial coulombic efficiency (10-20%), even lower than that of Si and SnO 2 nanoparticles with 410 3 Â contact area with the electrolyte, which is quite strange. Inspired by previous reports that tin catalyzes the decomposition of organic solvents, herein, we proved that bare Sn indeed catalyzes electrolyte decomposition at an intermediate voltage to generate gas bubbles and Leidenfrost films, which cut off the transport of lithium ions and prevent the formation of an adherent SEI. However, when the absolute potential is below 1 V (vs. Li/Li + ), it simultaneously promotes the formation of a solid SEI and mechanical adherence, which can in turn suppress future gassing. Therefore, we developed a roll-to-roll mechanical prelithiation process for tin foil, which lowers its absolute potential before contacting the electrolyte, promotes adherent passivation film formation, and greatly improves its coulombic efficiency and capacity retention so that it can perform well in full cells. Also, the striking air stability of the Li x Sn foil makes it much easier to handle than the bare Li metal anode. Our study provides vital new insights into why self-supporting metallic anodes do not appear to work in LIBs and develops an effective mitigation strategy by cheap and scalable metallurgical prelithiation, which is also applicable to other metallic alloy anode materials.

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