High-Energy Li-Ion Battery with Long Cycle Life Comprising Silicon-Based Anode and Layered Composite Cathode

Abstract

Currently, high-energy lithium ion batteries are in unprecedented demand for use in various energy storage applications including emerging electronic devices and a series of electrified vehicles. In this study, high capacity electrodes based on a Si composite anode and a layered composite oxide cathode, Ni-rich Li[Ni0.75Co0.1Mn0.15]O2, were evaluated and combined to fabricate a high energy lithium ion battery. The Si composite anode, Si/C-IWGS (Si/C composite internally wired with graphene sheets), was prepared by a scalable sol-gel process. The Si/C-IWGS anode delivered a high capacity of >800 mAh g-1 with excellent cycling stability up to 200 cycles mainly due to the small amount of graphene (i.e., ~6 wt%), which was ideally dispersed to maintain an electrical network in the composite against large volume changes. The cathode (Li[Ni0.75Co0.1Mn0.15]O2) was structurally optimized (Ni-rich core and a Ni-depleted shell with a continuous concentration gradient between the core and shell, i.e., full concentration gradient, FCG, cathode) so as to deliver a high capacity (>200 mAh g-1) with excellent stability at high voltage (~4.3 V). A novel lithium ion battery system based on the Si/C-IWGS anode and FCG cathode successfully demonstrated a high energy density (240 Wh kg-1 at least) as well as an unprecedented excellent cycling stability up to 750 cycles between 2.7 and 4.2 V at 1 C. As a result, the novel battery system can be an attractive candidate for energy storage applications demanding a high energy density and long cycle life.