High voltage electrolytes for lithium-ion batteries with micro-sized silicon anodes.

Micro-sized silicon anodes can significantly increase the energy density of lithium-ion batteries with low cost. However, the large silicon volume changes during cycling cause cracks for both organic-inorganic interphases and silicon particles. The liquid electrolytes further penetrate the cracked silicon particles and reform the interphases, resulting in huge electrode swelling and quick capacity decay. Here we resolve these challenges by designing a high-voltage electrolyte that forms silicon-phobic interphases with weak bonding to lithium-silicon alloys. The designed electrolyte enables micro-sized silicon anodes (5 µm, 4.1 mAh cm -2 ) to achieve a Coulombic efficiency of 99.8% and capacity of 2175 mAh g -1 for >250 cycles and enable 100 mAh LiNi 0.8 Co 0.15 Al 0.05 O 2 pouch full cells to deliver a high capacity of 172 mAh g -1 for 120 cycles with Coulombic efficiency of >99.9%. The high-voltage electrolytes that are capable of forming silicon-phobic interphases pave new ways for the commercialization of lithium-ion batteries using micro-sized silicon anodes.