The slow redox kinetics of polysulfides and the difficulties in decomposition of Li₂S during the charge and discharge processes are two serious obstacles to the practical application of lithium-sulfur batteries. Herein, we construct the Fe-Co diatomic catalytic materials supported by hollow carbon spheres to achieve high-efficiency catalysis for the conversion of polysulfides and the decomposition of Li₂S simultaneously. The Fe atom center is beneficial to accelerate the discharge reaction process, and the Co atom center is favorable for charging process. Theoretical calculations combined with experiments reveal that this excellent bifunctional catalytic activity originates from the diatomic synergy between Fe and Co atom. As a result, the assembled cells exhibit the high rate performance (the discharge specific capacity achieves 688 mAh g⁻¹ at 5 C) and the excellent cycle stability (the capacity decay rate is 0.018% for 1000 cycles at 1 C).

Oxygen vacancies (VO) have been considered as a significant strategy to improve the performance of catalysts in Li-S batteries. However, the highly active VO are a double-edged sword, as their instability can undermine long-term cycle performance. Therefore, it is essential to stabilize VO while maintaining their high activity. Here, five different metal elements are dissolved into the lattice structure of two-dimensional oxides to construct intrinsically stable and active VO for better lithium-sulfur catalysts. The unique electronic and crystal structure in high-entropy oxide endows the changed differentiated formation energies and high diffusion energy barrier of VO to form intrinsically stable VO. The Li-S batteries with stable VO in the electrocatalyst deliver a high specific capacity of 1301 mAh g−1 at 0.2C and low capacity fading of 0.032% per cycle after 2000 cycles at 1C. This work will inspire efforts on breaking the trade-off between activity and stability in heterogeneous catalysis beyond Li-S batteries.

Sodium ion batteries are attracting extensive interest due to their low cost and abundant sodium resources. However, sodium ion batteries still suffer from severe performance degradation at low temperatures due to the conflict between ion desolvation and diffusion. Herein, we design a co-intercalation ether electrolyte to achieve solvent co-intercalation in the hard carbon negative electrode, thereby bypassing the slow desolvation process while ensuring rapid ion diffusion in electrolyte and hard carbon. The optimized solvation structure also promotes the formation of a thin, inorganic-rich solid electrolyte interface, facilitating interfacial ion transport. As a result, the co-intercalation electrolyte enables hard carbon to deliver good low-temperature performance, with an initial Coulombic efficiency of 80.5% at −50°C (20 mA g ^-1 ) and a capacity retention of 93% after 200 cycles (100 mA g ^-1 ). Moreover, an Ah-level full cell retains cell stack-level (excluding packaging) specific energy of 163 Wh kg ^-1 at 25 °C and 107 Wh kg ^-1 at −50°C (100 mA g ^-1 ), demonstrating the practical feasibility of this strategy for wide-temperature sodium ion batteries. This work has the potential to overcome the long-standing trade-off between low-temperature ion desolvation and diffusion, offering an approach for electrolyte design toward wide-temperature sodium ion batteries.