xLi_2MnO_3-(l -x)LiMO_2 blended with LiFePO_4 to achieve high energy density and pulse power capability

摘要

A lithium-ion positive electrode is proposed that contains both high energy density and efficient pulse power capability, even at low state-of-charge (SOC). The pulse power capability at low SOC is attractive for applications, such as plug-in hybrid electric vehicles (PHEVs), which require pulse power operation over the entire useable SOC window. A lithium- and manganese-rich transition-metal layered-oxide (LMR-NMC), also classified as a layered-layered oxide material, is blended with a lithium iron phosphate (LFP) to achieve a potentially low-cost, high-performance electrode. The LMR-NMC material provides high energy by delivering cathode material gravimetric energy densities greater than 890 Wh kg1. The pulse power capability of this material at low SOC is greatly improved by incorporating a modest quantity of LFP. The LFP serves as an internal redox couple to charge and discharge the more rate-limited LMR-NMC material at moderate to low SOCs.