The O3-type NaNi_1/3Fe_1/3Mn_1/3O₂ (NFM) has emerged as a highly promising cathode material for sodium-ion batteries due to its facile synthesis and high theoretical capacity. However, it suffers from severe capacity and rate capability degradation caused by multiple coupled failure mechanisms, including irreversible phase transitions, structural deterioration at high voltages, and electrolyte-induced surface corrosion. This work addresses the challenge of high-voltage stability in NFM cathodes via a synergistic bulk-phase and interface engineering strategy. Firstly, Li, Ti, and Co are co-doped into the bulk lattice structure to suppress the Mn³⁺-induced Jahn-Teller distortion and improve Na⁺ diffusion kinetics. And then, an AlPO₄ protective coating layer is fabricated to mitigate electrolyte corrosion and interfacial side reactions. Consequently, the as-designed composite cathode (AP@NFMLTC) can effectively suppress the P3 to O3’ phase transition within the voltage range of 2.0 to 4.2 V, resulting in a highly reversible sodium storage mechanism. After 100 cycles at a rate of 1 C, the capacity retention rate significantly improves from 45.6% to 83.6%, with a minimal voltage decay of just 0.08 V. The dual bulk-interface synergistic strategy in this work provides valuable insights into achieving high stable operation for sodium-ion batteries (SIBs) cathodes under enhanced voltage.

Transition metal nitrides and carbides have attracted intensive attentions in metal-air battery application due to their metallic electron transport behavior and high chemical stability toward the oxygen reduction reaction (ORR). Herein, the polyoxometalate@polyaniline composite derived WN-W₂C heterostructured composite (WN-W₂C@pDC) has been fabricated through an in situ nitriding-carbonization strategy, with WN-W₂C nanoparticles implanted on N doped carbon nanorods. As-fabricated WN-W₂C@pDC demonstrates prominent electrocatalytic performance towards ORR and excellent cycling stability in metal-air battery, which possesses positive half-wave potential and large diffusion limiting current density (0.81 V and 5.8 mA·cm⁻²). Moreover, it demonstrates high peak power density of 157.4 mW·cm⁻² as Al-air primary cathode and excellent stability at the discharge–charge test (> 500 h) of Zn-air secondary battery. The excellent activity and durability of WN-W₂C@pDC catalyst should be attributed to the combined effect of intimate WN-W₂C heterointerfaces, unique embedded nanoparticles structure, and excellent electrical media of N doped carbon, confirmed by a series of contrast experiments.

Attributing to the high specific capacity and low electrochemical reduction potential, lithium (Li) metal is regarded as the most promising anode for high-energy Li batteries. However, the growth of lithium dendrites and huge volume change seriously limit the development of lithium metal batteries. To overcome these challenges, an ordered mesoporous N-doped carbon with lithiophilic single atoms is proposed to induce uniform nucleation and deposition of Li metal. Benefiting from the synergistic effects of interconnected three-dimensional ordered mesoporous structures and abundant lithiophilic single-atom sites, regulated local current density and rapid mass transfer can be achieved, leading to the uniform Li deposition with inhibition of dendrites and buffered volume expansion. As a result, the as-fabricated anode exhibits a high CE of 99.8% for 200 cycles. A stable voltage hysteresis of 14 mV at 5 mA cm⁻² could be maintained for more than 1330 h in the symmetric cell. Furthermore, the full cell coupled with commercial LiFePO₄ exhibits high reversible capacity of 108 mAh g⁻¹ and average Coulombic efficiency of 99.8% from 5th to 350th cycles at 1 C. The ordered mesoporous carbon host with abundant lithiophilic single-atom sites delivers new inspirations into rational design of high-performance Li metal anodes.