Besides, there is the degradation of the different components of the electrodes such as the binder, conductive additive, and the electrolyte. 23–30 However, Li-rich NMC cathodes still suffer from serious drawbacks such as the poor rate capabilities and the non-stable electrochemical performances (capacity and voltage fading) caused by the transition metals leaching during cycling and the crystal structures changes. Recently, Layered lithium-rich NMC (Li-rich NMC) has been extensively studied due to its enhanced performances, especially the high discharge capacity (>250 mA h g −1). To improve the structural stability and the electrochemical performance of Li(NiMnCo)O 2 based materials, various metal doping such as Al, Cr, Fe, Mo, Mg, Zr, and Si has been studied. 15,16 Therefore, the development of low-cost, non-toxic, and high-capacity cathode materials is needed. 14 However, Li(NiMnCo)O 2 has inherent disadvantages such as cation mixing, toxicity and high-capacity losses in the first discharge cycles. 10,12,13 One of the most common alternatives has been lithium nickel cobalt manganese oxides Li(NiMnCo)O 2 (NMC) due to their relative low cost, high capacity, and better thermal stability. 10,11 LiMn 2O 4 also suffers from severe capacity fading at high temperatures due to the Jahn-Teller distortion of Mn 3+, Mn ions' dissolution in electrolyte and the formation of two cubic phases and growth of microstrain. In addition, LiMnO 2 is thermodynamically unstable and tends to convert rapidly to LiMn 2O 4 during cycling. 7–9 Moreover, at higher temperatures, the exothermic decomposition of LiNiO 2 in the charged state causes safety issues. The synthesis of LiNiO 2 has been found to be challenging, and its capacity decreases rapidly due to the formation of the NiO 2 phase. 4–6 Nevertheless, several problems must be addressed. Other similar layered structure materials, such as LiNiO 2, LiMnO 2, and LiMn 2O 4 have been extensively studied as prospective cathode materials. 1–3 However, LiCoO 2, the first commercially available cathode material, is plagued by high costs, toxicity, and safety concerns. Introduction In recent years, lithium-ion batteries have been widely applied in portable electronic devices such as cellular phones, laptops, and power tools due to their high energy density, low self-discharge, and tiny memory effect. 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. In addition, when the Li 1.2Ni 0.13Mn 0.54Fe 0.1Co 0.03O 2 cathode was paired with a synthesized phosphorus-doped TiO 2 anode (P-doped TiO 2) in a complete battery cell, it exhibits good capacity and cycling stability at 1C rate. 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. 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. Importantly, improved voltage retention of 94% was achieved. The Li 1.2Ni 0.13Mn 0.54Fe 0.1Co 0.03O 2 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. Moreover, the effect of upper cut-off voltage on the structural stability, capacity and voltage retention was studied. A new Li 1.2Ni 0.13Mn 0.54Fe 0.1Co 0.03O 2 material with a higher content of Fe and lower content of Co was designed via a simple sol–gel method.
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