Coupling Anion‐Capturer with Polymer Chains in Fireproof Gel Polymer Electrolyte Enables Dendrite‐Free Sodium Metal Batteries

Abstract

Sodium metal batteries (SMBs) using gel polymer electrolytes (GPEs) with high theoretical capacity and low production cost are regarded as a promising candidate for high energy‐density batteries. However, the inherent flammability of GPEs and uncontrolled Na dendrite caused by inferior mechanical properties and interfacial stability hinder their practical applications. Herein, an anion‐trapping fireproof composite gel electrolyte (AT‐FCGE) is designed through a chemical grafting–coupling strategy, where functionalized boron nitride nanosheets (M‐BNNs) used as both nanosized crosslinker and anion capturer are coupled with poly(ethylene glycol)diacrylate in poly(vinylidene fluoride‐co‐hexafluoropropylene) matrix, to expedite Na+ transport and suppress dendrite growth. Experimental and calculation studies suggest that the anion‐trapping effect of M‐BNNs with abundant Lewis‐acid sites can promote the dissociation of salts, thus remarkably improving the ionic conductivity and Na+ transference number. Meanwhile, the formation of highly crosslinked semi‐interpenetrating network can effectively in situ encapsulate non‐flammable phosphate without sacrificing the mechanical properties. Consequently, the resulting AT‐FCGE shows significantly enhanced Na+ conductivity, mechanical properties, and excellent interfacial stability. The AT‐FCGE enables a long‐cycle stability dendrite‐free Na/Na symmetric cell, and prominent electrochemical performance is demonstrated in solid‐state SMBs. The approach provides a broader promise for the great potential of fire‐retardant gel electrolytes in high‐performance SMBs and the beyond.

Gel polymer electrolytes for rechargeable batteries toward wide-temperature applications

“…This leads to improved ionic conductivity, accelerated charge transfer kinetics, and enhanced interfacial stability. 348,349…”

Hexagonal Boron Nitride Modulates Crystallinity and Charge Mobility in Poly(ethylene oxide)–NaNO3 Electrolytes

“…Last, our DFT results also indicate the affinity of PEO toward h-BN (see Figure S8 in the Supporting Information), which further supports the enhanced nucleation model. Yang et al 33 reported a slightly higher ionic conductivity (×1.5) for BN nanosheet (BNNS)-containing Na gel polymer electrolytes relative to BN-free ones. The improvement in ionic conductivity was attributed to the anion-trapping ability of BNNS and the consequent increase in the free Na + concentration.…”

“…In the context of energy storage, investigations of structure–property relationships in BN-containing polymer electrolytes for Na-ion conduction are lacking. To the best of our knowledge, only a handful of recent reports have devoted attention to such polymer electrolyte systems. − Only one of these reports is based on a CSPE for Na-ion conduction, whereas the remainder of the studies is based on the incorporation of boron into the polymer chain rather than adding a BN-based filler to the polymer matrix. Chen et al , chemically incorporated boron into polymer chains and found a decrease in the total ionic conductivity compared to full-carbon polymer matrices.…”

“…32 Last, the physical incorporation of boron nitride nanosheets to GPEs by Liu and co-workers resulted in a marginal increase in total ionic conductivity. 33,34 While salts with low lattice energies and anions with high delocalization of charge are preferred for ionic conductivity enhancement, we choose NaNO 3 as a model salt in this work owing to its low cost and ease of availability, with the focus being on the effect of filler addition on structure− property relationships in the CSPEs. Notably, NaNO 3 has received little attention, with only two reports on its use in ether-based electrolytes such as PEO.…”

Anomalous Diffuson and Locon-Dominated Wigner Multi-Channel Thermal Transport in Disordered and Shear-Aligned Polymers

“…However, bulk polymers are usually thermal insulators, which hinders their capability to dissipate heat in emerging energy intensive applications. Thermal conductivities of bulk polymers are extremely low, on the order of 0.1 W m –1 K –1 , limiting their applications in electronics packaging, , fuel cells, , solar cell, , power batteries, , hydrogen generators, , heat exchangers, and aerospace materials . Polymer chain-aligned films − or fibers − exhibit a high thermal conductivity on the order of 10–100 W m –1 K –1 , which is close to the intrinsic high thermal conductivity of a well-aligned single polymer chain.…”