Rechargeable lithium-oxygen (Li-O₂) batteries have attractedwide attention due to their high energy density. However, the sluggish cathode kinetics results in high overvoltage and poor cycling performance. Ruthenium (Ru)-based electrocatalysts have been demonstrated to be promising cathode catalysts to promote oxygen evolution reaction (OER). It facilitates decomposition of lithium peroxide (Li₂O₂) by adjusting Li₂O₂ morphologies, which is due to the strong interaction between Ru-based catalyst and superoxide anion (O₂^-) intermediate. In this review, the design strategies of Ru-based electrocatalysts are introduced to enhance their OER catalytic kinetics in Li-O₂ batteries. Different configurations of Ru-based catalysts, including metal particles (Ru metal and alloys), single-atom catalysts, and Ru-loaded compounds with various substrates (carbon materials, metal oxides/sulfides), have been summarized to regulate the electronic structure and the matrix architecture of the Ru-based electrocatalysts. The structure-property relationship of Ru-based catalysts is discussed for a better understanding of the Li₂O₂ decomposition mechanism at the cathode interface. Finally, the challenges of Ru-based electrocatalysts are proposed for the future development of Li-O₂ batteries.

Lithium metal batteries (LMBs) have gained increasing attention owing to high energy density for large-scale energy storage applications. However, serious side reactions between Li anodes and organic electrolytes lead to low Columbic efficiency and Li dendrites. Although progress has been achieved in constructing electrode structures, the interfacial instability of Li anodes is still challenging. Solvation chemistry significantly affects the electrolyte properties and interfacial reactions, but the reaction mechanisms and the roles of each component in electrolytes are still vague. This review spotlights the recent development of electrolyte regulation with concentration and composition adjustments, aiming to understanding the correlation between solvation structures and Li anode stability. Further perspectives on the solvation design are provided in light of anode interfacial stability in LMBs.

Aprotic lithium-oxygen batteries (LOBs) with high theoretical energy density have received considerable attention over the past years. However, the oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) at cathodes suffer from slow kinetics for large overvoltages in LOBs. Significant advances on catalysts have been achieved to accelerate cathode kinetics, but understanding on the formation/decomposition processes of Li₂O₂ is limited. Herein, this review highlights the fundamental understanding of the correlation between catalysts and formation/decomposition of Li₂O₂. Various types of cathode catalysts are discussed to reveal the mechanism of formation/decomposition of Li₂O₂, aiming to present the prerequisites for the design of highly efficient cathode catalysts. Future prospects of comprehensive consideration on introduction of light or magnetism, protection of Li metal anode, and electrolyte engineering are presented for the further development of LOBs.

Surface strain engineering is considered as an effective strategy to promote the electrocatalytic properties of noble metal nanocrystals. Herein, we construct a dual-phase palladium-copper (DP-PdCu) bimetallic electrocatalyst with remarkable biaxial strain via a one-pot wet-chemical approach for formic acid oxidation. The biaxial strain originates from the lattice mismatch between the disordered face-centered cubic (FCC) phase and ordered body-centered cubic (BCC) phase in each of DP-PdCu nanoparticles. The proportion of FCC and BCC phases and size of PdCu nanoparticles are dependent on the addition amount of capping agent, cetyltrimethylammonium bromide (CTAB). Density functional theory calculations reveal the downshift of d-band center of Pd atoms due to the interfacial strain, which weakens the adsorption strength of undesired intermediates. These merit the DP-PdCu catalyst with superior mass activity of 0.55 A·mg_Pd⁻¹ and specific activity of 1.91 mA·cm_Pd⁻² toward formic acid oxidation, outperforming the single FCC/BCC PdCu and commercial Pd/C catalysts. This will provide new insights into the structure design of high-performance electrocatalysts via strain engineering.