An Energy‐Dense Solvent‐Free Dual‐Ion Battery

Abstract

Ever-increasing energy demands call for alternative energy storage technologies with balanced performance and cost characteristics to meet current and emerging applications. Dual-ion batteries (DIBs) are considered particularly attractive owing to the potentially high specific energy, a rich variety of charge carrier combinations, and the applicability of metal-free cathode and earth-abundant anode materials. However, their performance falls far below expectations because of a large excess of solvent needed to dissolve electroactive species that induces side reactions and contributes parasitic weight, which penalizes the reversible capacity and cell-level energy density. Herein, a solvent-free DIB utilizing a binary alkali metal molten salt based on bis(fluorosulfonyl)amide as the electrolyte to solve these issues is demonstrated. The cell (NaK-DIB) operates in a temperature range of 90-120 °C and exhibits high theoretical energy densities of 246 Wh kg −1 and 533 Wh L −1 based on active materials and capacity-matched electrolyte, far surpassing those of reported DIBs. Further improvements could realize affordable gridscale energy storage.

In Situ Monitoring of Lithium Metal Anodes and Their Solid Electrolyte Interphases by Transmission Electron Microscopy

“…The findings and the TEM approach provided in this work will definitely bring inspirations for the development of LMAs and other metallic anodes. [ 37,38 ]…”

Stacking Disorders in MixedAlkali Honeycomb Layered Oxide NaKNi2TeO6 and Feasibility for Mixed-Cation Transport

“…Given that batteries utilising both cation and anion as charge carriers (dual-ion batteries (DIBs)) have already shown remarkable metrics in terms of energy density, power density and cycling life, 42,[46][47][48] the present battery chemistry exploiting binary alkali metal cations could be a promising successor to DIB technology. By exploiting the synergistic effect of Na-and K-ion electrochemistry, the battery confers the aforementioned metrics besides taking advantage of the abundance of Na and K resources.…”

Advances and Prospects of Dual‐Ion Batteries

“…At the temperature of 90-120 °C, the DIB displayed a capacity of 108 mAh g -1 with an average operation voltage of 4.2 V. With this maximum limit electrolyte concentration, the energy density of DIB reached up to 246 Wh kg -1 (based on both the electrode materials and electrolyte), the best performance reported so far. [72] Despite these developments, there still exist challenges for concentrated electrolytes. Unlike PF 6 based salts, electrolytes based on TFSIand FSIare unable to passivate the Al foil current collector, and especially under the high working potential at the cathode side, the continuous corrosion of Al foil current collector leads to the low Coulombic efficiency of DIBs.…”