Li-Rich Cathode Material Enhancement through Atomic Surface Reduction

Abstract

Lithium Ion batteries (LIB) have revolutionized the portable electronics industry for over two decades, with high energy density, cycle capability and safety. In recent years the LIBs are the lead candidate to fuel the power demands of electric vehicles (EVs). However, current generation cathode materials fall short in terms of energy density for fulfilling the demands of future applications (energy storage, EVs, etc.). Li-Rich materials are the main contenders to become the next generation rechargeable li ion cathode material. Li-Rich materials are a family of layered materials which consist of Li, Mn, Co and Ni Oxides. One promising compound of Li-rich material contains two phases: X (Li 2 MnO 3 ) - (1-x) (LiMn a Ni b Co c O 2 ) where (a+b+c=1) . These materials exhibit high capacity (~250mAhrg-1 vs. ~170mAhrg-1 of current Generation cathodes), good stability and are safe for use. However, upon cycling, the Li-Rich cathodes suffer from voltage decay, which is currently attributed to be evolution of O 2 which causes a Redox process on the surface. We propose a new method for enhancement of the Li-rich cathode stability by controlled surface modification. The modification aims to control the oxygen evolution during cycling and thus control the voltage decay. This method shows improvement in the voltage stability during cycling and capacity retention. Figure 1