The application of sodium-based batteries in grid-scale energy storage requires electrode materials that facilitate fast and stable charge storage at various temperatures. However, this goal is not entirely achievable in the case of P2-type layered transition-metal oxides because of the sluggish kinetics and unfavorable electrode|electrolyte interphase formation. To circumvent these issues, we propose a P2-type Na0.78Ni0.31Mn0.67Nb0.02O2 (P2-NaMNNb) cathode active material where the niobium doping enables reduction in the electronic band gap and ionic diffusion energy barrier while favoring the Na-ion mobility. Via physicochemical characterizations and theoretical calculations, we demonstrate that the niobium induces atomic scale surface reorganization, hindering metal dissolution from the cathode into the electrolyte. We also report the testing of the cathode material in coin cell configuration using Na metal or hard carbon as anode active materials and ether-based electrolyte solutions. Interestingly, the Na||P2-NaMNNb cell can be cycled up to 9.2 A g−1 (50 C), showing a discharge capacity of approximately 65 mAh g−1 at 25 °C. Furthermore, the Na||P2-NaMNNb cell can also be charged/discharged for 1800 cycles at 368 mA g−1 and −40 °C, demonstrating a capacity retention of approximately 76% and a final discharge capacity of approximately 70 mAh g−1.

Efficient electrode materials, that combine high power and high energy, are the crucial requisites of sodium‐ion batteries (SIBs), which have unwrapped new possibilities in the areas of grid‐scale energy storage. Hard carbons (HCs) are considered as the leading candidate anode materials for SIBs, however, the primary challenge of slow charge‐transfer kinetics at the low potential region (<0.1 V) remains unresolved till date, and the underlying structure–performance correlation is under debate. Herein, ultrafast sodium storage in the whole‐voltage‐region (0.01–2 V), with the Na+ diffusion coefficient enhanced by 2 orders of magnitude (≈10–7 cm2 s–1) through rationally deploying the physical parameters of HCs using a ZnO‐assisted bulk etching strategy is reported. It is unveiled that the Na+ adsorption energy (Ea) and diffusion barrier (Eb) are in a positive and negative linear relationship with the carbon p‐band center, respectively, and balance of Ea and Eb is critical in enhancing the charge‐storage kinetics. The charge‐storage mechanism in HCs is evidenced through comprehensive in(ex) situ techniques. The as prepared HCs microspheres deliver a record high rate performance of 107 mAh g–1 @ 50 A g–1 and unprecedented electrochemical performance at extremely low temperature (426 mAh g–1 @ −40 °C).

Resin derived hard carbons (HCs) generally demonstrate remarkable electrochemical performance for both sodium ion batteries (SIBs) and potassium‐ion batteries (KIBs), but their practical applications are hindered by their high price and high temperature pyrolysis (≈1500 °C). Herein, low‐cost pitch is coated on the resin surface to compromise the cost, and meanwhile manipulate the microstructure at a relatively low pyrolysis temperature (1000 °C). HC‐0.2P‐1000 has a large number of short graphitic layer structures and a relatively large interlayer spacing of 0.3743 nm, as well as ≈1 nm sized nanopores suitable for sodium storage. Consequently, the as produced material demonstrates a superior reversible capacity (349.9 mAh g−1 for SIBs and 321.9 mAh g−1 for KIBs) and excellent rate performance (145.1 mAh g−1 at 20 A g−1 for SIBs, 48.5 mAh g−1 at 20 A g−1 for KIBs). Furthermore, when coupled with Na3V2(PO4)3 as cathode, the full cell exhibits a high energy density of 251.1 Wh kg−1 and excellent stability with a capacity retention of 73.3% after 450 cycles at 1 A g−1.

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To power large-scale energy storage systems, sodium-ion batteries (SIBs) must have not only high-energy density but also high performance under a low-temperature (LT) environment. P2-type manganese oxides with high specific capacity are promising cathode candidates for SIBs, but their LT applications are limitedly explored. We proposed a P2-type Na 0.67 Ni 0.1 Co 0.1 Mn 0.8 O 2 material with outstanding LT performance prepared through reasonable structure modulation. The material offers an excellent Na + diffusion coefficient (approximately 10 −9 -10 −7.5 cm 2 s −1 ) at −20°C, a superior LT discharge capacity of 147.4 mA h g −1 in the Na half-cell system, and outstanding LT full cell performance (energy density of 358.3 W h kg −1 ). Various characterisations and density function theory calculations results show that the solid solution reaction and pseudocapacitive feature promote the diffusion and desolvation of Na + from the bulk electrode to interface, finally achieving superior electrochemical performance at LT.