Single-atom catalysts based on metal−N 4 moieties and anchored on carbon supports (defined as M−N−C) are promising for oxygen reduction reaction (ORR). Among those, M−N−C catalysts with 4d and 5d transition metal (TM 4d,5d ) centers are much more durable and not susceptible to the undesirable Fenton reaction, especially compared with 3d transition metal based ones. However, the ORR activity of these TM 4d,5d −N− C catalysts is still far from satisfactory; thus far, there are few discussions about how to accurately tune the ligand fields of singleatom TM 4d,5d sites in order to improve their catalytic properties. Herein, we leverage single-atom Ru−N−C as a model system and report an S-anion coordination strategy to modulate the catalyst's structure and ORR performance. The S anions are identified to bond with N atoms in the second coordination shell of Ru centers, which allows us to manipulate the electronic configuration of central Ru sites. The S-anion-coordinated Ru−N−C catalyst delivers not only promising ORR activity but also outstanding longterm durability, superior to those of commercial Pt/C and most of the near-term single-atom catalysts. DFT calculations reveal that the high ORR activity is attributed to the lower adsorption energy of ORR intermediates at Ru sites. Metal−air batteries using this catalyst in the cathode side also exhibit fast kinetics and excellent stability.

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Lithium (Li) metal, a typical alkaline metal, has been hailed as the "holy grail" anode material for next generation batteries owing to its high theoretical capacity and low redox reaction potential. However, the uncontrolled Li plating/stripping issue of Li metal anodes, associated with polymorphous Li formation, "dead Li" accumulation, poor Coulombic efficiency, inferior cyclic stability, and hazardous safety risks (such as explosion), remains as one major roadblock for their practical applications. In principle, polymorphous Li deposits on Li metal anodes includes smooth Li (film-like Li) and a group of irregularly patterned Li (e.g., whisker-like Li (Li whiskers), moss-like Li (Li mosses), tree-like Li (Li dendrites), and their combinations). The nucleation and growth of these Li polymorphs are dominantly dependent on multiphysical fields, involving the ionic concentration field, electric field, stress field, and temperature field, etc. This review provides a clear picture and in-depth discussion on the classification and initiation/growth mechanisms of polymorphous Li from the new perspective of multiphysical fields, particularly for irregular Li patterns. Specifically, we discuss the impact of multiphysical fields' distribution and intensity on Li plating behavior as well as their connection with the electrochemical and metallurgical properties of Li metal and some other factors (e.g., electrolyte composition, solid electrolyte interphase (SEI) layer, and initial nuclei states). Accordingly, the studies on the progress for delaying/suppressing/ redirecting irregular Li evolution to enhance the stability and safety performance of Li metal batteries are reviewed, which are also categorized based on the multiphysical fields. Finally, an overview of the existing challenges and the future development directions of metal anodes are summarized and prospected.

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Using a collaborated in silico and experimental approach, we designed Sb-doped LiNiO2 with improved surface oxygen retention and electrochemical performance.

The rechargeability of aqueous zinc metal batteries is plagued by parasitic reactions of the zinc metal anode and detrimental morphologies such as dendritic or dead zinc. To improve the zinc metal reversibility, hereby we report a new solution structure of aqueous electrolyte with hydroxyl-ion scavengers and hydrophobicity localized in solvent clusters. We show that although hydrophobicity sounds counterintuitive for an aqueous system, hydrophilic pockets may be encapsulated inside a hydrophobic outer layer, and a hydrophobic anode–electrolyte interface can be generated through the addition of a cation-philic, strongly anion-phobic, and OH–-reactive diluent. The localized hydrophobicity enables less active water and less absorbed water on the Zn anode surface, which suppresses the parasitic water reduction; while the hydroxyl-ion-scavenging functionality further minimizes undesired passivation layer formation, thus leading to superior reversibility (an average Zn plating/stripping efficiency of 99.72% for 1000 cycles) and lifetime (80.6% capacity retention after 5000 cycles) of zinc batteries.

By using in situ and 3D electron microscopy, we decipher the chemomechanical degradation pathway of LiNiO 2 -based ultrahigh-nickel layered cathodes for lithium-ion batteries. We reveal that the O1 phase acts as a preferential nucleation site for rock-salt transformation via a two-step pathway involving cation mixing and shear along the (003) plane. Two types of cracks initiating from both the particle surface and interior as well as concurrent rock-salt phase transformation are uncovered. Our results provide deep understanding of the degradation mechanism of LiNiO 2 -derived cathodes.

Layered transition metal oxides are appealing cathodes for sodium‐ion batteries due to their overall advantages in energy density and cost. But their stabilities are usually compromised by the complicated phase transition and the oxygen redox, particularly when operating at high voltages, leading to poor structural stability and substantial capacity loss. Here an integrated strategy combing the high‐entropy design with the superlattice‐stabilization to extend the cycle life and enhance the rate capability of layered cathodes is reported. It is shown that the as‐prepared high‐entropy Na2/3Li1/6Fe1/6Co1/6Ni1/6Mn1/3O2 cathode enables a superlattice structure with Li/transition metal ordering and delivers excellent electrochemical performance that is not affected by the presence of phase transition and oxygen redox. It achieves a high reversible capacity (171.2 mAh g−1 at 0.1 C), a high energy density (531 Wh kg−1), extended cycling stability (89.3% capacity retention at 1 C for 90 cycles and 63.7% capacity retention at 5 C after 300 cycles), and excellent fast‐charging capability (78 mAh g−1 at 10 C). This strategy would inspire more rational designs that can be leveraged to improve the reliability of layered cathodes for secondary‐ion batteries.