High-Performance Rechargeable Aluminum–Selenium Battery with a New Deep Eutectic Solvent Electrolyte: Thiourea-AlCl₃

Abstract

Aluminum–sulfur batteries (ASBs) have attracted substantial interest due to their high theoretical specific energy density, low cost, and environmental friendliness, while the traditional sulfur cathode and ionic liquid have very fast capacity decay, limiting cycling performance because of the sluggishly electrochemical reaction and side reactions with the electrolyte. Herein, we demonstrate, for the first time, excellent rechargeable aluminum–selenium batteries (ASeBs) using a new deep eutectic solvent, thiourea-AlCl3, as an electrolyte and Se nanowires grown directly on a flexible carbon cloth substrate (Se NWs@CC) by a low-temperature selenization process as a cathode. Selenium (Se) is a chemical analogue of sulfur with higher electronic conductivity and lower ionization potential that can improve the battery kinetics on the sluggishly electrochemical reaction and the reduction of the polarization where the thiourea-AlCl3 electrolyte can stabilize the side reaction during the reversible conversion reaction of Al–Se alloying processes during the charge–discharge process, yielding a high specific capacity of 260 mAh g–1 at 50 mA g–1 and a long cycling life of 100 times with a high Coulombic efficiency of nearly 93% at 100 mA g–1. The working mechanism based on the reversible conversion reaction of the Al–Se alloying processes, confirmed by the ex situ Raman, XRD, and XPS measurements, was proposed. This work provides new insights into the development of rechargeable aluminum–chalcogenide (S, Se, and Te) batteries.

A General Template‐Induced Sulfuration Approach for Preparing Bifunctional Hollow Sulfides for High‐Performance Al‐ and Li‐ion Batteries

“…It is noted the anodic peak at 1.4 V shifts slightly during cycling, which is attributed to the polarization caused by the increase in resistance formed by the formation of solid electrolyte interface (SEI) film. [ 32 ]…”

Understanding the Photoexcitation of Room Temperature Ionic Liquids

“…Recent advances in developing batteries beyond lithium‐containing systems highlight reversible, i. e. rechargeable, conversion mechanisms of aluminum‐chalcogenide batteries with a thiourea‐AlCl 3 electrolyte. While this is not an ionic liquid, it is inspired by the large electrochemical window of the reference compound, an imidazolium chloride‐based RTIL, but with less side effects, e. g. the reaction of the RTIL cation with chalcogenides under electrochemical conditions [123] …”

Deep eutectics and analogues as electrolytes in batteries

“…The AlCl3:SU-based cell delivered a high specific capacity of 260 mAh g −1 at 50 mA g −1 with a high CE of ∼99% from the 5 th to 20 th cycles. 168 The electrolyte demonstrated good reversibility allowing a long cycling life of 100 times at a specific current of 100 mA g −1 with capacity of 195 mAh g −1 and CE of nearly 93%. The remarkable cycling performance were ascribed to the existence of multiple ionic species,…”

“…Elemental sulfur is one of the most promising cathode materials, as it is abundant, inexpensive and shows high theoretical capacity (1675 mAh g −1 ). 167,168 However, Li-S batteries usually face a few common troubles, especially the dissolution of lithium polysulfides, which are formed by the redox reaction at the S cathode and lead to low CE and quick capacity decay. 167 The use of LiTFSI:G3 and LiTFSI:G4 allowed to suppress the dissolution of lithium polysulfides compared with solutions containing an excess amount of glyme, leading to the stable operation of the Li-S battery over more than 400 cycles with discharge capacities higher than 700 mAh g −1 and with CEs higher than 98% throughout the cycles.…”

“…In the development of rechargeable Al−chalcogenide batteries, selenium (Se) is a candidate as cathode material, being a chemical analogue of S with much higher electronic conductivity (1 × 10 −3 S m −1 vs 5 × 10 −28 S m −1 ) and lower ionization potentials (9.7 eV vs 10.4 eV). 168 A DES based on AlCl3 and thiourea (SU) at 1.3:1 molar ratio was proposed as electrolyte for rechargeable aluminum−selenium (Al-Se) batteries with Se nanowires grown directly on a flexible carbon cloth substrate by a low-temperature selenization process. The AlCl3:SU-based cell delivered a high specific capacity of 260 mAh g −1 at 50 mA g −1 with a high CE of ∼99% from the 5 th to 20 th cycles.…”