Ultrahigh Ni-rich quaternary layered oxides LiNi1–x–y–z
Co
x
Mn
y
Al
z
O2 (1 – x – y – z ≥
0.9) are regarded as some of the most promising cathode candidates
for lithium-ion batteries (LIBs) because of their high energy density
and low cost. However, poor rate capacity and cycling performance
severely limit their further commercial applications. Herein, an in
situ coating strategy is developed to construct a uniform LiAlO2 layer. The NH4HCO3 solution is added
to a NaAlO2 solution to form a weak alkaline condition,
which can reduce the hydrolysis rate of NaAlO2, thus enabling
uniform deposition of Al(OH)3 on the surface of a Ni0.9Co0.07Mn0.01Al0.02(OH)2 (NCMA) precursor. The LiAlO2-coated samples show
enhanced cycling stability and rate capacity. The capacity retention
of NCMA increases from 70.7% to 88.3% after 100 cycles at 1 C with
an optimized LiAlO2 coating amount of 3 wt %. Moreover,
the 3 wt % LiAlO2-coated sample also delivers a better
rate capacity of 162 mAh g–1 at 5 C, while that
of an uncoated sample is only 144 mAh g–1. Such
a large improvement of the electrochemical performance should be attributed
to the fact that a uniform LiAlO2 coating relieves harmful
interfacial parasitic reactions and stabilizes the interface structure.
Therefore, this in situ coating approach is a viable idea for the
design of higher-energy-density cathode materials.
Single-crystal Ni-rich cathodes possess prominent structural integrity and thermal stability compared to the poly-crystal counterparts, yet their application at high-voltage is hampered by the intragranular cracks which remain intractable to...
This work introduces a one-step method for the preparation of layered oxide cathode materials utilizing pure Ni and Co mixed solution obtained from the waste hydrodesulfurization (HDS) catalyst. An efficient non-separation strategy with pyrometallurgical-hydrometallurgical (pyro-hydrometallurgical) process consisting of roasting and leaching is proposed. Most of the impurity metal elements such as Mo and V were removed by simple water leaching after the waste HDS catalyst was roasted with Na2CO3 at 650 °C for 2.5 h. Additionally, 93.9% Ni and 100.0% Co were recovered by H2SO4 leaching at 90 °C for 2.5 h. Then, LiNi0.533Co0.193Mn0.260V0.003Fe0.007Al0.004O2 (C–NCM) was successfully synthesized by hydroxide co-precipitation and high temperature solid phase methods using the above Ni and Co mixed solution. The final C–NCM material exhibits excellent electrochemical performance with a discharge specific capacity of 199.1 mAh g−1 at 0.1 C and a cycle retention rate of 79.7% after 200 cycles at 1 C. This novel process for the synthesis of cathode material can significantly improve production efficiency and realize the high added-value utilization of metal resources in a waste catalyst.
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