Fast Ion Conduction Nanofiber Matrix Composite Electrolyte for Dendrite‐Free Solid‐State Sodium‐Ion Batteries with Wide Temperature Operation

Abstract

Sodium‐ion batteries (SIBs) based on solid‐state electrolytes (SSEs), although safe for high temperatures, are less capable of transferring ions at ambient temperatures, let alone at low temperatures. This work offers a simple and scalable technique to construct a nanofiber matrix composite electrolyte with boosting Na+ transport and interfacial compatibility for SIBs. Benefitting from the salt dissociation and selective cation conduction synergistic effect of the acylamino, carbonyl, and ester groups in the low‐cost copolymer synthesized from 2‐(methacryloyloxy)ethyl acetoacetate and N,N′‐methylenebisacrylamide, a facilitating of Na+ transport at extreme temperatures is realized. Besides, flexible flame retardance ceramic SiO2 nanofibers greatly enhance high‐temperature safety. The ultrathin functional AlF3 layer generated by binder‐free magnetron sputtering suppresses the dendrites, eliminating the interfacial issues between the electrolyte and anode, which is proved by 5500 h of ultrasteady plating/stripping. Superior ionic conductivity of 0.153 mS cm−1 at −30 °C implies fast Na+ transport, which is further evidenced by molecular dynamics simulations. Rate performance at 0.05–10 C from −30 to 130 °C further demonstrates the excellent electrochemical performance of the electrolyte. This work provides encouraging guidance for high‐safety SSEs with rapid Na+ conduction for SIBs operating at extra‐wide temperatures.

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

“…Second, explaining in Region II, the selected PEGDA monomer contains abundant oxygen-containing groups (─C─O─C─, C═O), which can interact with Na + , thereby providing fast Na + transport path and improving ionic conductivity. [42] Finally, explaining in Region III, M-BNNs grafted with MPS contain amounts of C═C double bonds on B atoms, enabling it to act as nanosized crosslinker and undergo graft polymerization with polymer chains, which not only solves the problem of aggregation of inorganic fillers but also improves the mechanical properties of the electrolyte. Combining the above analysis, a fireproof composite gel electrolyte with outstanding ionic conductivity, enhanced mechanical properties, and excellent interfacial stability and safety would be successfully obtained.…”

“…To further explore the Na + transfer kinetic properties in electrolytes, molecular dynamics simulations (MDs) were carried out (details are present in the Experimental Section in Supporting Information). [42] Figure 2g shows the agglomeration morphology of the FCGE and AT-FCGE. The simulation snapshots display that the diffusion of Na + in AT-FCGE is significantly faster than that in the FCGE system without BNNs.…”

Enhancing the β Phase of Poly(vinylidene fluoride) Nanofibrous Membranes for Thermostable Separators in Lithium-Ion Batteries

“…19−21 However, traditional coating-modified strategies have not taken the membrane thickness and weight into consideration, which could lead to reduced LIB energy density. 22 Furthermore, the coating layer stripping from separators will not only dramatically lower the practical performance but also possibly cause serious LIB safety problems. 23 Particularly for LIBs with high energy density assembled in electric vehicles (for example, Tesla 4680), in order to achieve satisfactory cycle stability (i.e., preventing powder falling down during cycling), it is highly necessary to coat a big quantity of PVDF binders onto the separators.…”

“…Apart from the above properties of the separator, safety performance has always been the most concerning and crucial problem that requires urgent settlement . The ceramic nanoparticle coating has been proven to be an effective technique for improving the thermal stability of membranes. − However, traditional coating-modified strategies have not taken the membrane thickness and weight into consideration, which could lead to reduced LIB energy density . Furthermore, the coating layer stripping from separators will not only dramatically lower the practical performance but also possibly cause serious LIB safety problems …”

Antimony-Coated Carbon Nanocomposites as High-Performance Anode Materials for High-Temperature Sodium–Metal Batteries

“…Extensive studies have been conducted on various strategies, including electrolyte modification, interfacial protection engineering, and alloying interfaces, to address these challenges. These approaches aim to regulate ion distribution, control Na reactions with sodium–metal anode, and promote the formation of a stable SEI layer. − Pioneering studies have led to the development of various intermediate alloys with unlimited Na solubility, such as ZnO, Al 2 O 3 , SnO 2 , Au, Sb, and Sn particles, based on phase diagrams. These alloys are used to modify the scaffold structure, reducing nucleation barriers. − However, the presence of alloy species may cause agglomeration and electrical disintegration from the substrate. , Furthermore, the presence of direct contact between the alloys and the aprotic electrolyte can increase side reactions, resulting in irreversible consumption of Na + ions .…”