With the advancement of science and technology, people have put forward higher requirements for the energy density and safety performance of batteries. Because magnesium metal has the advantages of high volumetric specific capacity, no dendrite growth in the negative electrode, abundant earth reserves and low cost, it has huge commercialization potential in the field of low-cost and high-performance batteries. However, the development of magnesium secondary batteries has been limited by the lack of electrolyte and cathode materials. As a widely researched cathode material for conversion batteries, cheap and easily available sulfur brings hope to the development of cathode materials for magnesium secondary batteries. The theoretical energy density of the magnesium/sulfur battery system using magnesium metal as the negative electrode and sulfur as the positive electrode is as high as 1722Wh/kg, which is four times that of the current commercial lithium cobaltate/graphite battery system. It is a high specific energy and low cost battery with great development potential. Energy storage battery system.

Qingdao Energy Storage Industry Technology Research Institute, based on the previous work on magnesium secondary batteries, obtained a new type of organic magnesium borate-based electrolyte through one-step in-situ synthesis, which effectively improved the cycle of magnesium/sulfur batteries Performance and rate performance are expected to push the low-cost and high-energy density magnesium/sulfur battery system into practical use. The relevant research results are published in Energy&EnvironmentScience.

This research uses tris(hexafluoroisopropyl) borate (THFPB), magnesium chloride (MgCl2) and magnesium powder as raw materials, in ethylene glycol dimethyl ether (DME) solvent, through a one-step in-situ reaction to obtain [B( HFP)4]-is an anion, [Mg4Cl6(DME)6]2+ is an organic magnesium borate-based electrolyte. The electrolyte system exhibits excellent magnesium ion conductivity: the electrochemical window is as high as 3.3V (vs.Mg), the ion conductivity is as high as 5.58mS/cm, the electrodeposition overpotential is only 0.11V, and the coulombic efficiency of deposited dissolved magnesium exceeds 98. %. In addition, the electrolyte has excellent non-nucleophilic properties and is well compatible with sulfur cathodes. The magnesium/sulfur battery assembled with this electrolyte still has a specific discharge capacity of 1000mAh/g after 100 cycles of charge and discharge, and can still work normally under the condition of high current charge and discharge of 500mA/g. This is the current report The most excellent performance data in the research of magnesium-sulfur battery.

Simple synthesis method and excellent magnesium-sulfur battery performance are the biggest advantages of this organic magnesium borate-based electrolyte. This research result is expected to accelerate the practical process of magnesium/sulfur battery system