DEVELOPMENT OF AN ACCELERATED LIFE TEST FOR NICKEL HYDROGEN AND NICKEL-METAL HYDRIDE BATTERIES

THE PROPOSED ACCELERATED LIFE TESTING OF NICKEL HYDROGEN (NI-H) AND NICKEL METAL HYDRIDE (NI-HYDRIDE) BATTERIES USES IMPEDANCE SPECTROSCOPIC METHODS AS A DIAGNOSTIC FOR DETECTION OF AGING AND LIFE LIMITING PROCESSES. IN ADDITION, A THEORETICAL MODEL FOR THERMAL AND DEPTH OF DISCHARGE (DOD) STRESSES AS A MEANS OF ACCELERATING AGING IN THESE BATTERIES IS PROPOSED. THE IMPEDANCE SPECTROSCOPIC APPROACH USES A SERIES OF SPECTRAL FEATURES AS THE PRIMARY BATTERY LIFE DEGRADATION INDICATORS, AND TRI/AUSTIN WILL MEASURE THESE IN PHASE I ON NI-H AND NI-HYDRIDE CELLS WHICH ARE AT VARIOUS STAGES OF AGING AT EAGLE-PICHER, JOPLIN, MO. THROUGH ADVANCED DETECTION TECHNIQUES AND THEORETICALLY BASED ACCELERATION MODELS IT IS PREDICTED THAT NI-H AND NI-HYDRIDE ACCELERATED BATTERY TESTS CAN BE SHORTENED TO 6 MONTHS TO A YEAR COMPARED TO CURRENT TECHNOLOGY WHICH REQUEST 5 YEARS OF TESTING. TRI/AUSTIN WILL USE ITS EXISTING CAPABILITIES IN IMPEDANCE SPECTROSCOPY AND ACCELERATED TEST DESIGN TO REACH A FEASIBILITY DETERMINATION IN THE PHASE I TIME FRAME. BENEFITS RESULTING FROM REDUCED TEST TIME FOR BATTERIES TRANSLATE DIRECTLY INTO COST SAVINGS, AND THE SUCCESS OF THE PROPOSED EFFORT SHOULD REDUCE TEST COSTS FOR NI-H AND NI-HYDRIDE BATTERIES FIVE FOLD. COMMERCIAL BATTERY TEST COSTS WOULD BE REDUCED IN THE SAME MANNER, AND THERE IS THE POTENTIAL FOR AN INDUSTRY-WIDE STANDARD TEST PROCEDURE APPLICABLE TO A WIDE VARIETY OF BATTERY DEVELOPMENT EFFORTS.