A Crosslinked Polytetrahydrofuran‐Borate‐Based Polymer Electrolyte Enabling Wide‐Working‐Temperature‐Range Rechargeable Magnesium Batteries

Abstract

A polymer‐based magnesium (Mg) electrolyte is vital for boosting the development of high‐safety and flexible Mg batteries by virtue of its enormous advantages, such as significantly improved safety, potentially high energy density, ease of fabrication, and structural flexibility. Herein, a novel polytetrahydrofuran‐borate‐based gel polymer electrolyte coupling with glass fiber is synthesized via an in situ crosslinking reaction of magnesium borohydride [Mg(BH4)2] and hydroxyl‐terminated polytetrahydrofuran. This gel polymer electrolyte exhibits reversible Mg plating/stripping performance, high Mg‐ion conductivity, and remarkable Mg‐ion transfer number. The Mo6S8/Mg batteries assembled with this gel polymer electrolyte not only work well at wide temperature range (−20 to 60 °C) but also display unprecedented improvements in safety issues without suffering from internal short‐circuit failure even after a cutting test. This in situ crosslinking approach toward exploiting the Mg‐polymer electrolyte provides a promising strategy for achieving large‐scale application of Mg‐metal batteries.

Halide‐Based Materials and Chemistry for Rechargeable Batteries

“…The two half cells were collected and separated by a porous glass frit that could limit Br 2 diffusion and allow Mg 2+ exchange. The use of a room‐temperature Mg 2+ conductor will be necessary to enable the long‐term operation of this kind of battery …”

“…[61] Thet wo half cells were collected and separated by aporous glass frit that could limit Br 2 diffusion and allow Mg 2+ exchange.T he use of ar oomtemperature Mg 2+ conductor will be necessary to enable the long-term operation of this kind of battery. [338] Another MHB based on multivalent cation transfer is the rechargeable Al-I 2 battery.T ian et al have executed the proof-of-concept of this battery and attained highly reversible I 3 À /I À redox chemistry by using the polyvinylpyrrolidone/ iodine (PVP/I 2 )c omplex as the cathode and ar oom-temperature AlCl 3 /[EMIM]Cl electrolyte. [339] Thehydrogen-bonding interaction between the PVP and iodine species successfully mitigated the dissolution and shuttling of the iodine and polyiodides,w ith excellent stability even after 150 cycles at 1C.T he Al-I 2 electrochemical system can also be developed into ar edox-flow battery with the AlCl 3 /organic solvent eutectic system as the anolyte and the iodine-based species as the catholyte (I 3 À /I À ).…”

A High‐Rate Rechargeable Mg Battery Based on AgCl Conversion Cathode with Fast Solid‐State Mg2+ Diffusion Kinetics

“…Therefore, it is of great significance to explore new type of cathode materials. Electrochemical conversion reaction provides an alternative strategy to widen the options of Mg‐storage cathode, since it is not essentially constrained by the crystal lattice, and thus various kinds of electrode materials could be selected to construct Mg batteries . However, conversion‐type materials usually suffer from high activation energies during conversion reactions, and this issue will become more prominent for Mg batteries because of the bivalent Mg 2+ cation .…”

Magnesium Storage Performance and Mechanism of 2D‐Ultrathin Nanosheet‐Assembled Spinel MgIn2S4 Cathode for High‐Temperature Mg Batteries

“…Unfortunately, ordinary organic solvent electrolytes rapidly vaporize to form flammable gases with increasing temperature, leading to serious safety concerns . The poor safety limits the practical use of high temperature application fields, such as high‐temperature electronics devices, geothermal, and oil/gas borehole power sources …”