SBIR-STTR Award

Physical Sciences Inc. (PSI) proposes to form an electrochemical switch to prevent catastrophic failure in lithium-ion batteries by coating the cathode material with an electroactive polymer. The electroactive polymer can be reversibly “switched” from an insulator to a conductor upon oxidation permitting high rate capability during normal operation. In Phase I, PSI will demonstrate that upon a short or overdischarge the polymer reversibly switches to an insulator reducing the current flow to the cathode material. This reduced current flow will be demonstrated to decrease the localized heat generation by more than two orders of magnitude. PSI will also demonstrate that insulation of the cathode material limits irreversible degradation of the discharge capacity upon overdischarge maintaining cell balance and improving cycle life. In the Phase II program, we will scale up the coating procedure to produce cathode material on a production scale and demonstrate the technology in a 5Ah battery.

Keywords:
Lithium-Ion, Safety, Electroactive Polymer, Abuse Tolerance, Battery, Cathode, Internal Short

Physical Sciences, Inc. (PSI) has demonstrated that electroactive polymer coatings (EAP) may be applied to the surface of the cathode materials for lithium-ion batteries to protect against catastrophic cell failure. These EAP coatings form an electrochemical “switch” that can prevent catastrophic failure in lithium-ion batteries by reversibly changing from a conductor to an insulator on overdischarge or short-circuit of a cell. During a Phase II program PSI proposes to optimize and demonstrate on a prototype scale the EAP coatings. Laboratory scale batteries will be used to evaluate the cycling and rate performance of the coatings and select the optimal combination for scale-up. Pouch cells will then be constructed to demonstrate the safety benefits offered by the EAP coatings. Upon demonstration in a pouch cell, material will be delivered to SAFT America for the construction of cylindrical cells. The performance of these cells will be fully characterized and utilized to further optimize the coating before construction of additional cylindrical cells for delivery to the Air Force. Successful construction of the cylindrical cells and demonstration of improved battery safety will demonstrate the readiness of the EAP coatings for transition to a commercial or military application.

Keywords:
Lithium-Ion, Safety, Electroactive Polymer, Abuse Tolerance, Battery, Cathode, Internal Short