Electrochemical Analysis of Mechanically Flexible Magnesium-ion Battery Electrodes in a Polymer Gel Perchlorate Electrolyte

摘要

Over the past decade, rechargeable batteries based on lithium metal ion chemistries have enabled the practical development of many new products and technologies. Today, Li-ion batteries are often the primary means of providing electrical power to a diverse and growing number of devices, from mobile phones to electric vehicles. Despite many advances, Li-ion battery technologies suffer from some limitations that can prevent their use in emerging market sectors such as wearables, IoT, and grid-scale energy storage. While still in the research and development phase, it is anticipated that divalent metal-ion battery chemistries based on zinc or magnesium will present viable alternatives to conventional lithium-ion cells in these markets. Lithium ion batteries have a high theoretical gravimetric capacity of 3829mAh/g but only a modest volumetric capacity of 2044mAh/cm~3. By comparison, divalent batteries based on zinc or magnesium ions have theoretical volumetric capacities of 5854mAh/cm~3 and 3882mAh/cm~3 respectively. Volumetric capacity is especially important in IoT devices and wearables, where thin, flexible batteries which can cover large areas are ideal. In addition to a somewhat low volumetric capacity, lithium is far less common in the earth's crust than magnesium or zinc and possesses higher reactivity. Because of this, lithium-ion batteries are anticipated to be less environmentally friendly and cost effective than divalent metalion batteries in applications requiring many large battery cells. In this proceeding, we study the components of an experimental magnesium ion half-cell constructed from solid, flexible materials. A magnesium-ion cell was chosen due to its low material cost, good theoretical volumetric capacity, simple fabrication steps, and separator-free reaction chemistry. Flexible, insertion-type anodes and cathodes were fabricated using bismuth nanotubes and tungsten disulfide respectively. A polymer-based electrolyte made of PVDF-HFP and magnesium