The demand for transportation and grid applications has pushed the estimated market for high-performance lithium-ion batteries to exceed $43 billion by 2020. A growing concern is the safety hazards resulting from battery abuse, particularly overcharge/overdischarge. Lithium batteries are prone to energetic venting, ignition, and even explosion following severe overcharging. Even slight overcharge reduces the discharge capacity of a cell, potentially causing overdischarging, increased impedance, and local heating. Current protection methods of using electronic controls add significant weight and volume to the pack. The use of internal shutdown mechanisms reduces the usable capacity and adds to the burden of the remaining cells in parallel circuits. Complex re-routing of current around overcharged cells is expensive and impractical in large stacks. A novel approach was developed at LBNL where electroactive polymers capable of forming a voltage-regulated, reversible resistive shunt between the current collectors were introduced to prevent cells from overcharge damage. Recent progress, including the development of electroactive polymers that provide protection for high-energy cells intended for vehicular applications and novel electroactive-fiber membranes that largely reduce the cost and improve the stability of overcharge protection, will be presented. (1) G. Chen and T. J. Richardson, “Overcharge Protection for Rechargeable Lithium Batteries Using Electroactive Polymers,” Electrochem. Solid State Lett., 7, 23 (2004) (2) G. Chen, K. E. Thomas-Alyea, J. Newman, and T. J. Richardson, “Characterization of an Electroactive Polymer for Overcharge Protection in Secondary Lithium Batteries,” Electrochimica Acta, 50, 4666 (2005) (3) G. Chen and T. J. Richardson, “Overcharge Protection for 4 V Lithium Batteries at High Rates and Low Temperatures,” Journal of the Electrochemical Society, 157, A735 (2010) (4) B. Wang, T. J. Richardson and G. Chen, “Electroactive Polymer Fiber Separators for Stable and Reversible Overcharge Protection in Rechargeable Lithium Batteries,” Journal of the Electrochemical Society, 161, A1039 (2014

Electroactive separators for safer and longer lasting secondary lithium batteries

249th National Meeting (2015)

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