Electrolyte Development for Silicon-Based Anode Through High Throughput Screening

摘要

Driven by the ever-increasing demand of power consumption, extensive efforts have been stimulated for developing high energy density lithium-ion batteries (LIBs) to satisfy the power demands, such as in electronic devices, electric vehicles (EVs), and hybrid electric vehicles. Among all studied anode materials, silicon has been considered as one of the most promising anode materials to replace graphite because of its superior theoretical capacity (3587 mAh/g), attractive operating voltage (~0.4 V vs Li+/Li), natural abundance, and environmentally friendly properties. Despite multiple advantages, the commercialization of silicon has been hindered by the large volume variation (-300%), electrode pulverization, and more importantly the poor stability of the solid-electrolyte interphase (SEI) during cycling process. To alleviate the huge volume variation, 7%-15% of the silicon is typically incorporated with carbonaceous matrices to form the Si-C composites for practical application because of their low cost, high electric conductivity, and ductile properties to accommodate volume expansion as well as to form a stable SEI. At the meanwhile, fluoroethylene carbonate (FEC) has been widely applied for silicon anode materials considering its capabilities to efficiently improve the Coulombic efficiency and capacity retention through limiting the emergence of large cracks and preserving the original surface morphology. However, FEC additive still could not deliver desired cycling life to meet the requirement of EVs and sudden capacity fade issue is also frequently observed. Therefore, the demand for more robust additives is still needed for silicon anode materials. At Wildcat Discovery Technologies, we took advantage of high throughput technologies for additive screening. Hundreds of additives with various of functions can be quickly evaluated in actual full cell batteries. As a result, many additives were identified with similar or even better cycling performance over FEC. In this poster, our additive screening strategies and results will be discussed in detail.