Electroactive Polymer for Reversible Overcharge Protection in Lithium-Ion Batteries

Abstract

Great improvement in the safety of lithium ion battery is needed to meet the full requirements of electric vehicles (EV). Among these safety hazards, overcharge has long been recognized as a primary concern because it can lead to dangerous events such as thermal runaway, fire and explosion. The electroactive polymer approach utilizes the unique electronic properties of the polymers to form a reversible resistive shunt between the current collectors and protect the cell from overcharging. The process is self-activated by voltage, and it does not pose interference during normal cell charge and discharge. In this work, we report the recent progress in cell overcharge protection for high-energy-density lithium ion batteries. By incorporating the reversible electroactive polymers into highly porous membrane separators, we demonstrate that the composites can provide reversible and stable overcharge protection for a variety of cell chemistries. The results for the protection of Li1.05Mn1.95O4 or LiNi0.8Co0.15Al0.05O2 electrode will be discussed. Both cells were protected at a steady state voltage of 4.5 V for well over 100 cycles. ACKNOWLEDGEMENTS The authors would like to acknowledge the support from the Startup Foundation of China Academy of Engineering Physics, Institute of Chemical Materials (KJCX201301 and KJCX201306) and the Natural Science Foundation for Young Scientists of Sichuan province (No. 2014JY0202).The authors would like to acknowledge the support from the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Freedom CAR and Vehicle Technologies of the U.S. Department of Energy under Contract No. DE-AC02- 05CH11231.