Carbon Nanotube As Conductive Additive for Lithium Ion Batteries

Abstract

Silicon has been extensively studied as an anode material in lithium-ion batteries due to its extremely high theoretical specific capacity of 3578 mAh/g (Li15Si4). However, the huge volume fluctuations associated with this high cycling capacity create great challenges with regard to electrode mechanical integrity and continual electrolyte decomposition. Common strategies to alleviate this volume expansion are to study silicon alloys, silicon oxide, and to blend silicon materials with graphite active materials. Herein we study graphite-SiO blends in an attempt to achieve stable cycling performance. We study a wide variety of laminate formulations by varying the graphite/SiO ratio, the binder type, the conductive additive type, and the weight percent of each of these components. We find that the use of single-walled carbon nanotubes (SWCNT) as conductive additive is crucial to prevent rapid capacity fade during initial cycling. The use of SWCNT also enables the use of significantly less conductive additive and binder, likely providing both enhanced conductivity and mechanical stability to the electrode during volume fluctuation. Acknowledgement: We gratefully acknowledge the support from the U.S. Department of Energy’s Vehicle Technologies Office. This work is conducted under the Cell Analysis, Modeling, and Prototyping (CAMP) Facility at Argonne National Laboratory, a U.S. Department of Energy Office of Science Laboratory operated under Contract No. DE-AC02-06CH11357.