Li[Ni_0.5Mn_0.3Co_0.2]O₂ as a Superior Alternative to LiFePO₄ for Long-Lived Low Voltage Li-Ion Cells

Single crystal Li[Ni 0.5 Mn 0.3 Co 0.2 ]O 2 //graphite (NMC532) pouch cells with only sufficient graphite for operation to 3.80 V (rather than ≥4.2 V) were cycled charging either 3.65 or facilitate comparison LiFePO 4 (LFP) on the grounds of similar maximum potential and negative electrode utilization. The NMC532 cells, when constructed be charged V, have an energy density that exceeds LFP a cycle-life greatly at 40 °C, 55 °C 70 °C. Excellent lifetime high temperature is demonstrated electrolytes contain lithium bis(fluorosulfonyl)imide (LiFSI) salt, well beyond those provided by conventional LiPF 6 electrolytes. Ultra-high precision coulometry electrochemical impedance spectroscopy are used complement cycling results investigate reasons improved performance NMC cells. particularly balanced 3.8 show better coulombic efficiency, less capacity fade higher compared projected yield lifetimes approaching century 25