Single‐Ion Conducting Polymer Electrolyte for Superior Sodium‐Metal Batteries

Abstract

Sodium‐metal batteries (SMBs) are considered a potential alternative to high‐energy lithium‐metal batteries (LMBs). However, the high reactivity of metallic sodium towards common liquid organic electrolytes renders such battery technology particularly challenging. Herein, we propose a multi‐block single‐ion conducting polymer electrolyte (SIPE) doped with ethylene carbonate as suitable electrolyte system for SMBs. This novel SIPE provides a very high ionic conductivity (2.6 mS cm‐1) and an electrochemical stability window of about 4.1 V at 40 °C, enabling stable sodium stripping and plating and excellent rate capability of Na||Na3V2(PO4)3 cells up to 2C. Remarkably, such cells provide a capacity retention of about 85% after 1,000 cycles at 0.2C thanks to the very high Coulombic efficiency (99.9%), resulting from an excellent interfacial stability towards sodium metal and the Na3V2(PO4)3 cathode.

In situ formed self-embedded ion/electron conductive skeletons enabling highly stable sodium metal anodes

“…High-energy rechargeable batteries built with low-cost sodium (Na)-metal anodes are expected to replace lithium batteries in renewable energy markets because of the high theoretical capacity (1166 mA h g −1 ) and abundant resources of metallic Na in the Earth's crust (2.3 wt%). [1][2][3][4] Unfortunately, the practical application of sodium metal batteries (SMBs) has been long impeded by the uncontrollable dendrite growth, unstable solid electrolyte interface (SEI) films, and huge volume changes. [5][6][7] Thereinto, the dendrite growth induced by uneven Na deposition will pierce through the separator, resulting in a short circuit of the battery and even triggering a series of safety hazards.…”

Cellulose-Encapsulated Composite Electrolyte Design: Toward Chemically and Mechanically Enhanced Solid-Sodium Batteries

“…Polymer electrolytes exhibit enhanced mechanical properties, yet suffer from relatively low room-temperature Na + conductivity, low transference number (for dual-ion electrolytes), and limited electrochemical stability window. − The ionic conductivity of polymer electrolytes depends strongly on the glass transition temperature of the polymer matrix, which defines the optimal temperature for polymer chain relaxation to access reasonable ion mobility. Although single-ion polymer electrolytes designed for unity transference numbers have been reported, − their electrochemical stability still needs to be improved.…”

In-Situ Polymerized Solid-State Polymer Electrolytes for High-Safety Sodium Metal Batteries: Progress and Perspectives

“…Until now, a series of polymer matrices including poly(ethylene oxide) [20], poly(vinylidene fluoridehexafluoro propylene) [21], poly(acrylonitrile) [22], poly(methyl vinyl ether-altmaleic anhydride) [23], and other new polymers [24][25][26][27][28][29][30][31][32][33][34][35][36] have been proposed and prepared as SPEs for LIBs and SIBs. Nevertheless, these above-stated SPEs are prepared mainly by ex-situ preparation methods (e.g., solution-casting method), which are time-consuming and complicated.…”