Sodium-based battery development

Quasi-solid-state polymer electrolytes are ideal candidates for practical secondary battery applications. Here, the authors propose a negatively charged (–COO^–)-modified covalent organic framework as a Na-ion quasi-solid-state electrolyte with sub-nanometric Na-ion transport zones.

Sodium-sulfur batteries show potential as attractive alternatives to Li-ion batteries due to their high energy density but practicality is hampered by sodium polysulfide issues. Here, the authors introduce an intercalation-type catalyst MoTe2 to improve the redox kinetics in Na-S batteries.

Oxygen redox in transition metal oxides enhances the energy content of Na-ion batteries but is typically plagued by poor reversibility. Here, the authors achieve non-hysteresis through the formation of a spin singlet state to stabilize the active oxygen redox reaction in P3-type Na_2/3Cu_1/3Mn_2/3O₂.

Sluggish kinetics is a major challenge for iron-based sulfate electrode materials. Here, the authors report multiscale interface engineering to build continuous Na-ion transfer channels at all length scales by designing ionic conductors inside bulk and low-electron-density exposed crystal surfaces.

P2-Na_2/3[Fe_1/2Mn_1/2]O₂ is a promising high energy density cathode material for rechargeable sodium-ion batteries, but its poor long-term stability in the operating voltage window of 1.5–4.25 V vs Na⁺/Na hinders its commercial application. Here, the authors use a combination of electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy, and DFT calculations to investigate the origin of the capacity fading, which is attributed to an increase in bulk electronic resistance at high voltage that, among other factors, is nested in a structural phase transition.

The inclusion of nickel and manganese in layered sodium metal oxide cathodes for sodium ion batteries is known to improve stability, but the redox behaviour at high voltage is poorly understood. Here in situ X-ray spectroscopy studies show that the redox behaviour of oxygen anions can account for an increase in specific capacity at high voltages.

Bi-phasic O3/P2 sodium layered oxides are leading candidates for next-generation batteries but rational control of the O3/P2 ratio remains challenging. Here, the O3/P2 ratio is tuned by using the average ionic radius of the transition metal layer, leading to materials with different characteristics.

Aqueous sodium-ion batteries show promise for large-scale energy storage, yet face challenges due to water decomposition, limiting their energy density and lifespan. Here, the authors report a cathode surface coating strategy in an alkaline electrolyte to enhance the stability of both electrolyte and battery.

Mn-based Prussian blue is an ideal positive electrode material for aqueous sodium-ion batteries but still suffers from Mn dissolution. Here, the authors introduce an Mn-ion trapping agent as an electrolyte additive to produce a 94 Wh kg−1 Na-ion aqueous battery with a long lifespan.