Owing to the large surface area and adjustable surface properties, the two‐dimensional (2D) MXenes have revealed the great potential in constructing hybrid materials and for Na‐ion storage (SIS). In particular, the facilitated Na‐ion adsorption, intercalation, and migration on MXenes can be achieved by surface modification. Herein, a new surface modification strategy on MXenes, namely, the reactive surface modification (RSM), is focused and illustrated, while the recent advances in the research of SIS performance based on MXenes and their derivatives obtained from the RSM process are briefly summarized as well. In the second section, the intrinsic surface chemistries of MXenes and their surface‐related physicochemical properties are first summarized. Meanwhile, the close relationship between the surface characters and the Na‐ion adsorption, intercalation, and migration on MXenes is emphasized. Following the SIS properties of MXenes, the surface‐induced SIS property variations, and the SIS performance of RSM MXene‐based hybrids are discussed progressively. Finally, the existing challenges and prospects on the RSM MXene‐based hybrids for SIS are proposed.

Stabilizing Na+ accessibility at high voltage and accelerating Na+ diffusivity are pressing issues to further enhance the energy density of the Na3V2(PO4)3 (NVP) cathode for sodium-ion batteries (SIBs). Herein, by taking a V/Cr solid-solution MXene as a precursor, a facile in-situ reactive transformation strategy to embed Cr-substituted NVP (NVCP) nanocrystals in a dual-carbon network is proposed. Particularly, the substituted Cr atom triggers the accessibility of additional Na+ in NVCP, which is demonstrated by an additional reversible redox plateau at 4.0 V even under extreme conditions. More importantly, the Cr atom alters the Na+ ordering at the Na2 sites with an additional intermediate phase formation during charging/discharging, thus reducing the energy barriers for Na+ migration. As a result, Na+ diffusivity in NVCP accelerates to 2–3 orders of magnitude higher than that of NVP. Eventually, the NVCP cathode exhibits extraordinarily high-rate capability (78 mA g–1 at 200 C and 68975 W kg–1), outstanding cycle stability (over 1500 cycles at 10 C), excellent low-temperature property, and full cell performance.

Polyanionic transition metal polyphosphate (TMPO)-type Na 3 V 2 (PO 4 ) 2 O 2 F (NVPO 2 F) is promising as cathode for large-scale sodium-ion batteries (SIBs) on account of its considerable capacity and highly stable structure. However, the redox of transition metal and phase transitions along with the (de) intercalation of Na + lead to its slow kinetics and inferior rate performance. Herein, chlorine (Cl) is applied as a heteropical dopant to obtain Cl-doped NVPO 2 F (NVPO 2−x Cl x F) cathode material for SIBs. Density functional theory investigation reveals that Cl doping tunes the localized electronic density and structure in NVPO 2 F lattice, causing the electron redistribution on vanadium center and dangling anions. Hence, the NVPO 2−x Cl x F cathode exhibits a revised redox behavior of vanadium for Na + extraction/insertion, increases Na + diffusion rate, as well as lowers charge transfer resistance. A Na + storage mechanism of reversible transformations between three phases and V 4+ /V 5+ redox couple for NVPO 2−x Cl x F cathode is verified. The NVPO 2−x Cl x F cathode reveals a high rate capacity of ≈63 mAh g −1 at 30C and great cycle stability over 1000 cycles at 10C. More importantly, outstanding rate property (314 Wh kg −1 at 5850 W kg −1 ) and cycling capability are obtained for the NVPO 2−x Cl x F//3DC@Se full cell. This study demonstrates a brand-new strategy to prepare advanced cathode materials for superior SIBs.

Anionic Doping In article number 2109694, Hong Yu, Cheng‐Feng Du, Xing‐Long Wu, and co‐workers develop Cl‐doped Na3V2(PO4)2O2F (NVPO2−xClxF) as superior cathode material for sodium‐ion batteries. In NVPO2−xClxF, Cl doping tunes the electronic structure and causes the electron redistribution on vanadium center/dangling anions. As a result, a revised redox behavior of vanadium and increased Na+‐ diffusivity/electrochemical properties are achieved.

Addressing the structural instability and torpid kinetic limitation has been a pressing while challenging issue for vanadium oxide cathode materials to realize their outstanding performance in rechargeable aqueous zinc-ion batteries...