headlines, [3][4][5] for which the highly flammable nonaqueous electrolytes used in LIBs are mainly responsible. It is under this context that aqueous LIBs (ALIBs) are revisited as a fundamental solution to safety, despite their low energy densities due to the narrow electrochemical stability window of water. [2,[6][7][8][9][10] Recently, a new class of high-voltage aqueous electrolyte was discovered by dissolving 21 molality (mol) lithium bis(trifluoromethane sulfonyl) imide (LiTFSI) in 1 kg of water. Such a "water-in-salt" electrolyte (WiSE) expands the electrochemical stability window from 1.23 to 3.0 V, which supports a 2.5 V chemistry using LiMn 2 O 4 (LMO) cathode and Mo 6 S 8 anode to stably deliver ≈100 Wh kg −1 for thousand cycles. The significantly improved electrochemical stability therein mainly comes from the depletion of free water molecules and the formation of an anion-derived solid-electrolyte interphase (SEI) on the anode surface. [9] However, because of the intrinsic repulsion of anions and adsorption of the Li + -4(H 2 O) solvates by the negatively polarized anode surface, [4] the formation of such an anion-derived SEI has been impossible below 1.9 V versus Li + /Li. [9] This "cathodic challenge" has essentially excluded many desired energy-dense anodes that operate at low potentials such as Li-metal, graphite, or silicon. Even Li 4 Ti 5 O 12 (LTO) that operates at mild potential (≈1.70 V Li + /Li in WiSE) suffers from irreversibility, because it sits right on the edge of the cathodic limit in WiSE. Efforts aiming to resolve the "cathodic challenge" with additional lithium salts such as lithium trifluoromethane sulfonate (LiOTf) [11] or lithium bis(pentafluoroethane sulfonyl) imide (LiBETI) [10] achieved limited success, because solubility limits of the salts impose restrictions on how high their concentration can go, while the effectiveness of added anions still faces intrinsic resistance from anode surface against their accumulation at inner-Helmholtz layer, not to mention that these additional salts further worsen the already problematic viscosity and ionic conductivity of WiSE. Introducing a nonaqueous solvent, dimethyl carbonate (DMC), [12] into WiSE expands the electro chemical window of the hybrid electrolyte to 4.1 V, because the neutral solvent is less sensitive to anode repulsion and hence participates in interphasial chemistry more easily than anions. The additional protection from an SEI consisting of both anion-and solvent-derived products enables LTO operation Although the "water-in-salt" electrolyte has significantly expanded the electrochemical stability window of aqueous electrolytes from 1.23 to 3 V, its inevitable hydrogen evolution under 1.9 V versus Li + /Li prevents the practical use of many energy-dense anodes. Meanwhile, its liquidus temperature at 17 °C restricts its application below ambient temperatures. An advanced hybrid electrolyte is proposed in this work by introducing acetonitrile (AN) as co-solvent, which minimizes the presence of interfacial water at the nega...

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Lithium (Li) metal batteries have long been deemed as the representative high‐energy‐density energy storage systems due to the ultrahigh theoretical capacity and lowest electrochemical potential of Li metal anode. Unfortunately, the intractable dendritic Li deposition during cycling greatly restrains the large‐scale applications of Li metal anodes. Recent advances have been explored to address this issue, among which a specific class of electrolyte additives for electroplating is deeply impressive, as they are economic and pragmatic. Different from the conventional additives that construct solid electrolyte interphase (SEI) layer on anodes, they make dendrite‐free Li metal anodes feasible through altering Li plating behavior. In this research news article, the interlinked principles between industrial electroplating and Li deposition are firstly illustrated. The featured effects of electroplating additives on regulating Li plating morphology are also summarized and mainly divided into three categories: co‐deposition with Li cation, coordination with Li cation, and leveling effect of Li films. Furthermore, the mechanism exploration or derivative use of electroplating additive for dendrite suppression and potential research directions are proposed, with emphasizing that industrial electroplating might enable Li metal anode to scalable battery techniques and spread to metal battery systems beyond Li.

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