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The dissolution/shuttling of sodium polysulfides, coupled with sodium dendrites growth, severely compromises the lifespan and stability of room temperature sodium–sulfur (RT Na–S) batteries. Herein, it proposes employing a functionalized porous ZIF‐based membrane (PZM) to address these two challenges. First, the metal ions embedded within the zeolitic imidazolate framework chemically bind with polysulfide anions, curtailing their detrimental shuttling. Second, the tailored porous structure of the membrane ensures a selective and uniform pathway for sodium ions, significantly reducing non‐uniform deposition and curbing dendritic sodium growth. Third, the intrinsically non‐combustible nature of the ZIF‐based membrane acts as a fortification against thermal outbursts and electrolyte decomposition. Implementing this polysulfide‐resistant, dendrite‐inhibiting and flame‐retardant PZM with a standard S/C cathode leads to the creation of a robust separator with lean electrolyte RT Na–S battery. This configuration may impart a novel perspective for the advancement and enhancement of RT Na–S battery systems. [ABSTRACT FROM AUTHOR]

Na3(VOPO4)2F (NVOPF) is an ideal cathode for high-energy-density sodium ion batteries (SIBs), due to its impressive output voltage and stable structure. However, the high production costs and complex operation processes associated with conventional synthetic methods impede its commercial applications. Herein, a simple but efficient method for large-scale low-cost synthesis of NVOPF at low temperatures is proposed. The optimal sample obtained at a suitable pH delivers a high discharge capacity of 119.6 mA h g−1 at 0.2C and remarkable cycling performance with a decay rate of merely 0.0043% per cycle over 1400 cycles at 1C. Coin-type full cells composed of NVOPF and commercial hard carbon achieve a distinguished energy density of 426.2 W h kg−1 calculated based on the cathode material. Most importantly, 2.1 A h soft-pack batteries with 100 mm in length and 60 mm in width were assembled based on the as-synthesized kilogram-scale NVOPF, which can stably cycle at 1C for 400 cycles with a capacity retention of 93.2% and an average coulombic efficiency of 99.96%. Moreover, the soft-pack battery exhibits fascinating performance in a wide temperature range, including superior rate capability at −20 °C (86.4% at 5C compared to 1C) as well as stable cycling performance at 50 °C (72.5% capacity retention after 400 cycles at 1C). This paper proposes a low-temperature co-precipitation method for synthesizing NVOPF, which significantly reduces the cost of production and contributes a solution for the industrial-scale production of NVOPF. [ABSTRACT FROM AUTHOR]

Cyclodextrin, which has the advantages of being resource-rich, low cost, eco-friendly, high purity and good stability, is a potential precursor to prepare hard carbons for sodium ion batteries (SIBs), but is rarely explored so far. In this work, a simple and commercializable pre-crosslinking strategy was developed to modulate the local structure of cyclodextrin-derived carbons, because the direct carbonization of cyclodextrin leads to a limited capacity of 154.7 mA h g−1. The original cyclic monomer structure of cyclodextrin is transformed into a three-dimensional cross-linked structure via carbonyl groups as binding sites. The cross-linking reaction tends to produce more sp3-hybrid carbon, which finally results in more curved and shorter carbon layers as well as much more closed pores. Thus, the best sample obtained with a thirty-minute pre-crosslinking treatment delivers an improved reversible specific capacity of 332.5 mA h g−1 at a current density of 30 mA g−1 with an initial Coulombic efficiency of 83.4%, where the low-voltage plateau region (230.1 mA h g−1) contributes up to 70% of the total capacity. To the best of our knowledge, this work offers a tentative exploration of cyclodextrin-derived carbons for the first time, which possibly opens up the investigation of this new kind of carbon anode. [ABSTRACT FROM AUTHOR]

Sodium dentrite formed by uneven plating/stripping can reduce the utilization of active sodium with poor cyclic stability and, more importantly, cause internal short circuit and lead to thermal runaway and fire. Therefore, sodium dendrites and their related problems seriously hinder the practical application of sodium metal batteries (SMBs). Herein, a design concept for the incorporation of metal–organic framework (MOF) in polymer matrix (polyvinylidene fluoride‐hexafluoropropylene) is practiced to prepare a novel gel polymer electrolyte (PH@MOF polymer‐based electrolyte [GPE]) and thus to achieve high‐performance SMBs. The addition of the MOF particles can not only reduce the movement hindrance of polymer chains to promote the transfer of Na+ but also anchor anions by virtue of their negative charge to reduce polarization during electrochemical reaction. A stable cycling performance with tiny overpotential for over 800 h at a current density of 5 mA cm−2 with areal capacity of 5 mA h cm−2 is achieved by symmetric cells based on the resulted GPE while the Na3V2O2(PO4)2F@rGO (NVOPF)|PH@MOF|Na cell also displays impressive specific cycling capacity (113.3 mA h g−1 at 1 C) and rate capability with considerable capacity retention. [ABSTRACT FROM AUTHOR]