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critical challenges to be overcome for the successful utilization of Li-rich cathodes in LIBs. Li-rich cathodes suffer from severe voltage decay and continued capacity fading upon repeated cycling mainly because of two unfavorable reactions: 1) the interfacial degradation that stems from an unstable cathode-electrolyte interphase and 2) the irreversible phase transformation from layered to spinel. [9][10][11] Undesirable electrolyte decomposition at the Li-rich cathode with a high operation voltage of 4.4 V versus Li/Li + causes irreparable damage to the cathode-electrolyte interface (CEI), such as inhomogeneous delithiation induced by a nonuniform surface coverage of decomposition byproducts and the consumption of active Li + ions and electrons. [12,13] The second issue, irreversible phase transformation, which is most likely the major reason for voltage decay, is not fully understood. This transformation is closely linked to a reduction in the valence state of transition metal ions in the Li-rich cathode and propagates gradually from the interface to the bulk as the cycle progresses. [11,14] On the basis of the aforementioned reports, at a high voltage, the highly oxidized transition metal ions are prone to take electrons from the electrolyte components to lower their valence state, resulting in their phase transformation from layered to spinel. [15] The formation of a stable CEI by additives can improve the electrochemical performance of Li-rich cathodes while mitigating the sustained occurrence of unfavorable phase transformations through reforming the cathode interface. [16][17][18][19][20] Moreover, the decrease in the valence state of the transition metal ions leads to the release of oxygen (O 2 ) and superoxide radicals (O 2 •− ) to maintain the charge balance in the cathode during subsequent cycling. [21][22][23] Electrochemical activation of Li 2 MnO 3 in a Li-rich cathode above 4.4 V versus Li/Li + on the first charge inevitably evolves reactive oxygen species, including oxygen gas (O 2 ) and superoxide radicals (O 2 •− ), in a cell. [22,24] The reactive superoxide radical (O 2 •− ) generated from the Lirich cathode produces gaseous products such as CO and CO 2 through reaction with the ethylene carbonate (EC) solvent in the electrolyte and accordingly causes a sudden termination of battery operation by electrolyte depletion. [15,25] Therefore, scavenging the reactive oxygen species serves as an effective way to improve the electrochemical performance of Li-rich cathodes.High-capacity Li-rich layered oxide cathodes along with Si-incorporated graphite anodes have high reversible capacity, outperforming the electrode materials used in existing commercial products. Hence, they are potential candidates for the development of high-energy-density lithium-ion batteries (LIBs). However, structural degradation induced by loss of interfacial stability is a roadblock to their practical use. Here, the use of malonic acid-decorated fullerene (MA-C 60 ) with superoxide dismutase activity and water scavenging capabil...

Despite the enormous potential of aqueous zinc (Zn)‐ion batteries as a cost‐competitive and safer power source, their practical applications have been plagued by the chemical/electrochemical instability of Zn anodes with aqueous electrolytes. Here, ionic liquid (IL) skinny gels are reported as a new class of water‐repellent ion‐conducting protective layers customized for Zn anodes. The IL skinny gel (thickness ≈500 nm), consisting of hydrophobic IL solvent, Zn salts, and thiol‐ene polymer compliant skeleton, prevents the access of water molecules to Zn anodes while allowing Zn2+ conduction for redox reactions. The IL‐gel‐skinned Zn anode enables sustainable Zn plating/stripping cyclability under 90% depth of discharge (DODZn) without suffering from water‐triggered interfacial parasitic reactions. Driven by these advantageous effects, a Zn‐ion full cell (IL‐gel‐skinned Zn‐anode||aqueous‐electrolyte‐containing MnO2 cathode) exhibits high charge/discharge cycling performance (capacity retention ≈95.7% after 600 cycles) that lies beyond those achievable with conventional aqueous Zn‐ion battery technologies.

With a recent increase in interest in metal-gas batteries, the lithium-carbon dioxide cell has attracted considerable attention because of its extraordinary carbon dioxide-capture ability during the discharge process and its potential application as a power source for Mars exploration. However, owing to the stable lithium carbonate discharge product, the cell enables operation only at low current densities, which significantly limits the application of lithium-carbon dioxide batteries and effective carbon dioxide-capture cells. Here, we investigate a high-performance lithium-carbon dioxide cell using a quinary molten salt electrolyte and ruthenium nanoparticles on the carbon cathode. The nitrate-based molten salt electrolyte allows us to observe the enhanced carbon dioxide-capture rate and the reduced dischargecharge over-potential gap with that of conventional lithium-carbon dioxide cells. Furthermore, owing to the ruthernium catalyst, the cell sustains its performance over more than 300 cycles at a current density of 10.0 A g −1 and exhibits a peak power density of 33.4 mW cm −2 .

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