Pre-Lithiation of Anode for Lithium Ion Batteries

Abstract

Silicon monoxide (SiO), as an anode for lithium ion batteries (LIB), offers a specific capacity of 1750 mAh/g and a volumetric capacity of 1547 Wh/L,[1] which is less than Si, but still a significant improvement from the current commercial graphite anode, which has a specific capacity of 350 mAh/g and a volumetric capacity of 719 Wh/L. Compared to Si, SiO offers much more stable cycling, and is therefore the more practical material for near-future applications. The drawback of SiO is the large capacity loss observed in the initial cycles. The 1st cycle coulombic efficiency of silicon monoxide is usually lower than 70% due to the parasitic reactions between lithium and the oxide.To address the problem, prelithiation reagents can be added to either anode or cathode electrodes to compensate for the lithium loss caused by the irreversible reactions. However, dead weight left by the pre-lithiation agent adversely affects the energy density of LIB. Electrochemical pre-lithiation will only put the lithium ions into the anode and leaves no other compound behind, which is considered an ideal prelithiation method. In addition, the electrochemical pre-lithiation on the anode has the potential to be compatible with the existing roll-to-roll manufacturing line and could be immediately applicable to the current state-of-the-art LIB anodes.In this work, we conducted the electrochemical pre-lithiation of large size graphite and SiO anode electrodes in pouch cells to prove the concept. After pre-lithiation, no damage and handling issues were encountered during subsequent cleaning, drying, cell fabrication, and testing. Good electrochemical performance of the pre-lithiated graphite and SiO electrodes were obtained in both half cells and full cells. According to calculation, the pre-lithiation speed is challenging and needs to be addressed to match roll-to-roll electrode coating speed. Additionally, electrochemical pre-lithiation on graphite powder was attempted and results will be discussed. Acknowledgements: We gratefully acknowledge the support from Peter Faguy at the U.S. Department of Energy’s (DOE) office of Energy Efficiency & Renewable Energy (EERE) Vehicle Technologies Office. This work is conducted under the Cell Analysis, Modeling, and Prototyping (CAMP) Facility at Argonne National Laboratory. Argonne National Laboratory is a U.S. Department of Energy Office of Science Laboratory operated under Contract No. DE-AC02-06CH11357.[1] Obrovac, M. N.; Chevrier, V. L., Alloy Negative Electrodes for Li-Ion Batteries. Chemical Reviews 2014, 114 (23), 11444-11502.