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Gel‐polymer electrolyte (GPE) is a pragmatic choice for high‐safety sodium batteries but still plagued by interfacial compatibility with both cathode and anode simultaneously. Here, salt‐in‐polymer fibers with NaF salt inlaid in polylactide (PLA) fiber network was fabricated via electrospinning and subsequent in situ forming gel‐polymer electrolyte in liquid electrolytes. The obtained PLA‐NaF GPE achieves a high ion conductivity (2.50×10−3 S cm−1) and large Na+ transference number (0.75) at ambient temperature. Notably, the dissolution of NaF salt occupies solvents leading to concentrated‐electrolyte environment, which facilitates aggregates with increased anionic coordination (anion/Na+ >1). Aggregates with higher HOMO realize the preferential oxidation on the cathode so that inorganic‐rich and stable CEI covers cathode' surface, preventing particles' breakage and showing good compatibility with different cathodes (Na3V2(PO4)3, Na2+2xFe2‐x(SO4)3, Na0.72Ni0.32Mn0.68O2, NaTi2(PO4)3). While, passivated Na anode induced by the lower LUMO of aggregates, and the lower surface tension between Na anode and PLA‐NaF GPE interface, leading to the dendrites‐free Na anode. As a result, the assembled Na || Na3V2(PO4)3 cells display excellent electrochemical performance at all‐climate conditions. [ABSTRACT FROM AUTHOR]

Polymer electrolytes provide a visible pathway for the construction of high‐safety quasi‐solid‐state batteries due to their high interface compatibility and processability. Nevertheless, sluggish ion transfer at room temperature seriously limits their applications. Herein, a triangular synergy strategy is proposed to accelerate Na‐ion conduction via the cooperation of polymer‐salt, ionic liquid, and electron‐rich additive. Especially, PVDF‐HFP and NaTFSI salt acted as the framework to stably accommodate all the ingredients. An ionic liquid (Emim+‐FSI−) softened the polymer chains through a weakening molecule force and offered additional liquid pathways for ion transport. Physicochemical characterizations and theoretical calculations demonstrated that electron‐rich Nerolin with π‐cation interaction facilitated the dissociation of NaTFSI and effectively restrained the competitive migration of large cations from EmimFSI, thus lowering the energy barrier for ion transport. The strategy resulted in a thin F‐rich interphase dominated by NaTFSI salt's decomposition, enabling rapid Na+ transmission across the interface. These combined effects resulted in a polymer electrolyte with high ionic conductivity (1.37×10−3 S cm−1) and tNa+ (0.79) at 25 °C. The assembled cells delivered reliable rate capability and stability (200 cycles, 99.2 %, 0.5 C) with a good safety performance. [ABSTRACT FROM AUTHOR]

Phosphorus exhibits high capacity and low redox potential, making it a promising anode material for future sodium‐ion batteries. However, its practical applications are confined by poor durability and sluggish kinetics. Herein, an innovative in‐situ electrochemically self‐driven strategy is presented to embed phosphorus nanocrystal (≈10 nm) into a Fe‐N‐C‐rich 3D carbon framework (P/Fe‐N‐C). This strategy enables rapid and high‐capacity sodium ion storage. Through a combination of experimental assistance and theoretical calculations, a novel synergistic catalytic mechanism of Fe‐N‐C is reasonably proposed. In detail, the electrochemical formation of Fe‐N‐C catalytic sites facilitates the release of fluorine in ester‐based electrolyte, inducing Na+‐conducting‐enhanced solid‐electrolyte interphase. Furthermore, it also effectively induces the dissociation energy of the P‐P bond and promotes the reaction kinetics of P anode. As a result, the unconventional P/Fe‐N‐C anode demonstrates outstanding rate‐capability (267 mAh g−1 at 100 A g−1) and cycling stability (72%, 10 000 cycles). Notably, the assembled pouch cell achieves high‐energy density of 220 Wh kg−1. [ABSTRACT FROM AUTHOR]

Hard carbon is one of the most promosing anodes for resource‐rich sodium‐ion batteries. However, an unsatisfactory solid–electrolyte‐interphase formed by irreversible electrolyte consumption caused by defects or oxygen‐containing functional groups of hard carbon impedes its further application. Herein, a novel composite binder that is composed of polar polymer chondroitin sulfate A (sodium salt) and polyethylene oxide by hydrogen bonding demonstrates defect passivation capability. This composite binder can reduce the exposure of defects by forming hydrogen bonds with oxygen functional groups on the hard carbon surface and inhibit the decomposition of electrolyte confirmed by in situ differential electrochemical mass spectrometry. In situ Raman and theoretical calculations reveal that multiple polar functional groups in chondroitin sulfate A (sodium salt) can accelerate the transport of Na+ by adsorbing and facilitate the decomposition of PF6− to form NaF. Additionally, polyethylene oxide in the composite binder can increase viscosity and accelerate the transport of Na+. As a result, an ultra‐thin (9 nm, cyro‐TEM) and NaF‐rich solid–electrolyte interphase is obtained, thereby the hard carbon anode achieves improved initial Coulombic efficiency (84%) and high‐capacity retention of 94% after 150 cycles in a NaPF6/ethylene carbonate/dimethyl carbonate electrolyte. [ABSTRACT FROM AUTHOR]

Understanding and controlling parasitic reactions on the Zn metal anode (ZMA) surface is essential to enhance the energy capabilities of aqueous zinc‐ion batteries (ZIBs). However, the accurate regulation scheme is often obscured due to the lack of fundamental understanding concerning the ZMA/electrolyte interface. Herein, the descriptor of interfacial parasitic reactions is revealed through a systematic comparative study of three model trace adsorption‐type pyridinesulfonic acid‐based additives with structural variations. Using in situ spectroscopies coupled with density functional theory calculations, direct spectroscopic evidence of interfacial H2O evolution during Zn2+ deposition process is obtained. It is proposed that, beyond the traditional cognitions, the distance between solvated Zn(H2O)62+ and ZMA surface highly dictates the stability of ZMAs. Consequently, the trace 3‐Pyridinesulfonic acid with most effective capacity to drive solvated Zn(H2O)62+ away from the ZMA surface, enables a robust cycle life over 420 h for the Zn||Zn symmetric cell at 10 mA cm−2/10 mAh cm−2 (depth of discharge of 45%), a high Coulombic efficiency of 99.78% and an extended cycling life of 1500 cycles for the Zn//NH4V4O10 full battery. The work sheds light on the underlying mechanism of parasitic reactions on ZMA surface and provides fundamental insights into the design of trace additives for better ZIBs. [ABSTRACT FROM AUTHOR]