Limiting voltage and capacity fade of lithium-rich, low cobalt LiNiMnFeCoO by controlling the upper cut-off voltage.

A new LiNiMnFeCoO material with a higher content of Fe and lower content of Co was designed a simple sol-gel method. Moreover, the effect of upper cut-off voltage on the structural stability, capacity and voltage retention was studied. The LiNiMnFeCoO electrode delivers a discharge capacity of 250 mA h g with good capacity retention and coulombic efficiency at 4.6 V cut-off voltage. Importantly, improved voltage retention of 94% was achieved. XRD and Raman proved that the electrodes cycled at 4.8 V cut-off voltage showed huge structural conversion from layered-to-spinel explaining the poor capacity and voltage retention at this cut-off voltage. In addition, FT-IR demonstrates that the upper cut-off voltage of 4.8 V exhibits a higher intensity of SEI-related peaks than 4.6 V, suggesting that reducing the upper cut-off voltage can inhibit the growth of the SEI layer. In addition, when the LiNiMnFeCoO cathode was paired with a synthesized phosphorus-doped TiO anode (P-doped TiO) in a complete battery cell, it exhibits good capacity and cycling stability at 1C rate. The material developed in this study represents a promising approach for designing high-performance Li-rich, low cobalt cathodes for next-generation lithium-ion batteries.