Limiting voltage and capacity fade of lithium-rich, low cobalt Li1.2Ni0.13Mn0.54Fe0.1Co0.03O2 by controlling the upper cut-off voltage

Abstract

A new Li_1.2Ni_0.13Mn_0.54Fe_0.1Co_0.03O₂ material with a higher content of Fe and lower content of Co was designed via a simple sol–gel method. Moreover, the effect of upper cut-off voltage on the structural stability, capacity and voltage retention was studied. The Li_1.2Ni_0.13Mn_0.54Fe_0.1Co_0.03O₂ electrode delivers a discharge capacity of 250 mA h g⁻¹ with good capacity retention and coulombic efficiency at 4.6 V cut-off voltage. Importantly, improved voltage retention of 94% was achieved. Ex situ 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, ex situ 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 Li_1.2Ni_0.13Mn_0.54Fe_0.1Co_0.03O₂ cathode was paired with a synthesized phosphorus-doped TiO₂ anode (P-doped TiO₂) 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.