Abstract
Structural instability during cycling is an important factor affecting the electrochemical performance of nickel-rich ternary cathode materials for Li-ion batteries. In this work, enhanced structural stability and electrochemical performance of LiNi0.6Co0.2Mn0.2O2 cathode materials are achieved by Ga doping. Compared with the pristine electrode, Li[Ni0.6Co0.2Mn0.2]0.98Ga0.02O2 electrode exhibits remarkably improved electrochemical performance and thermal safety. At 0.5C rate, the discharge capacity increases from 169.3 mAh g−1 to 177 mAh g−1, and the capacity retention also rises from 82.8% to 89.8% after 50 cycles. In the charged state of 4.3 V, its exothermic temperature increases from 245.13 °C to more than 271.24 °C, and the total exothermic heat decreases from 561.7 to 225.6 J·g−1. Both AC impedance spectroscopy and in situ XRD analysis confirmed that Ga doping can improve the stability of the electrode/electrolyte interface structure and bulk structure during cycling, which helps to improve the electrochemical performance of LiNi0.6Co0.2Mn0.2O2 cathode material.
Highlights
With the rapid development of portable electronic products and electric vehicles, higher requirements have been put forward on the energy density, safety, cycle life, and cost of lithium-ion batteries (LIBs)
One useful method is to coat the surface of NCM622 material with Al2 O3 [13], Co3 O4 [14], SiO2 [15], Li3 PO4 [16], Mn3 (PO4 )2 [17], Li1.3 Al0.3 Ti1.7 (PO4 )3 [18], LiAlO2 [19], and Li2 Si2 O5 [20] in order to improve the stability of the electrode/electrolyte interface and, enhance the capacity, Coulomb efficiency, cyclability, and thermal safety performance
(108)/(110) rose, and the ratio of c/a gradually increased from 4.9485 for the sample prepared at 800 ◦ C to 4.9548 for the sample prepared at 900 ◦ C, indicating an improved cation ordering
Summary
With the rapid development of portable electronic products and electric vehicles, higher requirements have been put forward on the energy density, safety, cycle life, and cost of lithium-ion batteries (LIBs). One useful method is to coat the surface of NCM622 material with Al2 O3 [13], Co3 O4 [14], SiO2 [15], Li3 PO4 [16], Mn3 (PO4 )2 [17], Li1.3 Al0.3 Ti1.7 (PO4 )3 [18], LiAlO2 [19], and Li2 Si2 O5 [20] in order to improve the stability of the electrode/electrolyte interface and, enhance the capacity, Coulomb efficiency, cyclability, and thermal safety performance Another effective method is to prepare heterogeneous structural materials. The research on Ga doping to improve the electrochemical performance of nickel-rich LiNi1−x−y Cox Mny O2 materials seems necessary In this project, the high-temperature solid-state reaction method was employed to synthesize Ga-doped NCM622 materials. The Ga-doped materials prepared under the optimized synthesis conditions exhibited remarkably improved structural stability and electrochemical performance
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