A new lithium battery technology promises to extend the lifetime of batteries and keep electric A pouch cell next to a Canadian $2 coin. Source: J.R. Dahn et al.A pouch cell next to a Canadian $2 coin. Source: J.R. Dahn et al.vehicles (EVs) on the road longer. Researchers at Canada’s Dalhousie University developed a moderate-energy-density, lithium-ion, pouch cell chemistry expected to power an EV for more than one million miles and last at least two decades in grid energy storage.

The results of long-term benchmark tests conducted on single crystal lithium-nickel-manganese-cobalt oxide/artificial graphite cells with lithium salt-based electrolyte are reported in the Journal of the Electrochemical Society. Storage and cycle tests were conducted for up to three years at 20° C, 40° C and 55° C.

Cell chemistry proved extremely tolerant to extended periods at elevated temperatures, and only cells stored at 55° C and 4.3 V for 1.3 years showed signs of capacity loss and impedance growth. Aged units had virtually no charge endpoint capacity slippage, indicating that no species were oxidized.

Differential voltage analysis demonstrated that lithium inventory loss associated with thickening of the negative electrode solid-electrolyte interphase is the major degradation mechanism for these cells. After 5,300 cycles, no evidence of microcracking was observed in particles that were initially less than 3 micrometers in size. The results confirm the advantages of single crystal materials, which also account for the stability of the positive electrode active mass in cells during cycling.

The battery chemistry was developed under a licensing agreement with Tesla Motors.

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