Achieving Ultra‐Stable All‐Solid‐State Sodium Metal Batteries with Anion‐Trapping 3D Fiber Network Enhanced Polymer Electrolyte

Abstract

All‐solid‐state sodium metal batteries paired with solid polymer electrolytes (SPEs) are considered a promising candidate for high energy‐density, low‐cost, and high‐safety energy storage systems. However, the low ionic conductivity and inferior interfacial stability with Na metal anode of SPEs severely hinder their practical applications. Herein, an anion‐trapping 3D fiber network enhanced polymer electrolyte (ATFPE) is developed by infusing poly(ethylene oxide) matrix into an electrostatic spun fiber framework loading with an orderly arranged metal‐organic framework (MOF). The 3D continuous channel provides a fast Na+ transport path leading to high ionic conductivity, and simultaneously the rich coordinated unsaturated cation sites exposed on MOF can effectively trap anions, thus regulating Na+ concentration distribution for constructing stable electrolyte/Na anode interface. Based on such advantages, the ATFPE exhibits high ionic conductivity and considerable Na+ transference number, as well as enhanced interfacial stability. Consequently, Na/Na symmetric cells using this ATFPE possess cyclability over 600 h at 0.1 mA cm−2 without discernable Na dendrites. Cooperated with Na3V2(PO4)3 cathode, the all‐solid‐state sodium metal batteries (ASSMBs) demonstrate significantly improved rate and cycle performances, delivering a high discharge capacity of 117.5 mAh g−1 under 0.1 C and rendering high capacity retention of 78.2% after 1000 cycles even at 1 C.

Wide-temperature-range sodium-metal batteries: from fundamentals and obstacles to optimization

“…It consists of a polymer matrix as a solvent and a salt solution that can be dissolved in the polymer matrix. 270,271 To synthesize high-conductivity SPE, a satisfactory sodium salt is expected to have superior solubility, thermal stability and electrochemical stability. 272,273 Typically, common sodium salts mainly include NaTFSI, NaPF 6 , NaClO 4 , NaBF 4 , sodium difluoro-(oxalate)borate (NaDFOB) and NaFSI.…”

“…It consists of a polymer matrix as a solvent and a salt solution that can be dissolved in the polymer matrix. 270,271…”

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

“…Among all the negative electrode materials of sodium batteries, due to the low redox potential (−2.71 V vs standard hydrogen potential) and material/production cost, high theoretical capacity (1166 mA h g −1 ) of sodium metal, sodium metal batteries (SMBs) using Na metal anode show excellent development potential in the field of rechargeable batteries. [4][5][6][7][8] However, for the commercialized SMBs using liquid electrolyte system, the side reactions between sodium metal and electrolyte are easy to occur, causing uneven sodium plating/stripping and serious dendrite growth in the circulation process, which lead to a short circuit or failure of batteries. [9,10] In addition, due to the high volatility, leakage and inflammability of liquid electrolyte, SMBs exist serious potential safety hazards.…”

Metal–Organic Framework-Coated Fiber Network Enabling Continuous Ion Transport in Solid Lithium Metal Batteries

“…This represents an 11-fold improvement when compared to the ionic conductivity of the pure PEO electrolyte, which was 5.1 × 10 –6 S cm –1 . However, it is worth noting that the ease of MOF nanoparticle aggregation presents a significant challenge when attempting to mix them with polymers to create uniform solid polymer electrolytes. ,,− The incorporation of an inorganic fiber skeleton to create a three-dimensional structure material has been identified as a promising approach to extend the application range of MOFs.…”