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The U.S. Army has been pursuing vehicle electrification to achieve enhanced combat effectiveness. The benefits include new capabilities that require high power pulse duty cycles. However as the vehicle platform size decreases, the Energy Storage System (ESS) pulse power discharge rates (> 40 C rate) to support system requirements can be significantly greater than commercial ESS. Results are reported of high power pulse duty cycles on lithium iron phosphate cells that show a dramatic loss in lifetime performance. For a 2 s and 3 s pulse duration tests, the observed degradation is 22 % and 32 % respectively. Although these cells were thermally managed in a convective chamber at 10°C, the 2 s pulse showed a 31°C temperature rise and the 3 s pulse, a 48°C temperature rise. The decreased lifetime is attributed to increased lithium loss due to the increased temperature during pulse discharging.

Solid-state lithium-ion batteries that use a solid electrolyte may potentially operate at wide temperatures and provide satisfactory safety. Moreover, the use of a solid electrolyte, which blocks the formation of lithium dendrites, allows batteries to use metallic lithium for the anode, enabling the batteries gain an energy density significantly higher than that of traditional lithium-ion batteries. Solid electrolytes play a role of conducting lithium ions and are the core of solid-state lithium-ion batteries. However, the development of solid lithium electrolytes towards a high lithium ionic conductivity, good chemical and electrochemical stability and scalable manufacturing method has been challenging. We report a new material composed of nitrogen-doped lithium metaphosphate, denoted as NLiPO3.