First-principles study on solid electrolyte interphases on graphene anodes of lithium-ion batteries

Lithium-ion batteries are major power sources for portable electronic devices with many merits. A typical lithium-ion battery system consists of an anode, cathode, and non-aqueous liquid electrolyte. Solid electrolyte interphase (SEI) refers to the solid layer covering the anode and is formed due to the decomposition of the electrolytes. SEI is electrically insulating yet sufficiently conductive to lithium ions. It prevents further decomposition of the electrolyte. SEI plays a critical role in influencing the battery performance, including the cycle life, self-discharge, safety, faradic efficiency and irreversible capacity. The chemistry of the formation process of SEI strongly depends on the type of anode and electrolyte materials, as well as the process of fabrication. Nowadays, with super surface area, graphene is an advanced anode material for fast charging lithium ion batteries. During the fast charging-recharging process, the large current, heat, and strains occur. Under these extreme conditions, the SEI formation and integrity is curial for the performance and safety of the advanced lithium ion batteries. We therefore propose to use first-principles calculations to model the reduction reactions of the electrolyte of the lithium ion battery with fast-charging conditions. These products then further react with ions to form solid sediments on the surface of graphene nanosheets anodes. These sediments eventually to form porous network as frames of the SEI. We will examine the optimized structure of SEI on the surface of anodes that consist of graphene nanosheets. This proposed research shall bring insights towards the advancement of the lithium-ion battery technology to a new horizon, to have fast-charging, high-reliable, high-capacity renewable green power source that contributes the vision 2030.