Simulation of Fast-Charging Performance of Bilayer Anode Lithium-ion Batteries

Abstract

Lithium-ion batteries currently represent the system of choice for automakers to move away from direct fossil fuel combustion by utilizing electricity generated from environmentally friendly sources such as wind or solar electricity. However, the inability for a lithium-ion battery to charge in a timely manner while having sufficient energy density presents a challenge for mass adoption. Currently commercialized lithium-ion batteries employ a graphite anode due to its low cost, high electrical conductivity, and high energy density. However, a graphite anode suffers from spatial variation in reaction rates when subjected to fast charging conditions, causing cell polarization and often irreversible lithium plating. Another carbon allotrope, hard carbon, has better fast-charging performance, but in turn has a lower energy density and a higher first-cycle capacity loss. Thus, by combining the two anode materials, anode performance and properties can potentially be balanced to alleviate the tradeoff between energy density and fast-charging capability. Through analysis of the interactions between two layers of different materials in the anode using computational modeling, this study evaluates the effect that a bilayer composite anode has on the fast-charging performance of a lithium-ion battery.