Abstract
In this paper, the precursor Ni0.8Co0.1Mn0.1(OH)2 is prepared by a co-precipitation method. By mixing this material with LiOH in proportion and sintering twice under 500℃ and 800 ℃, respectively, the cathode material of LiNi0.8Co0.1Mn0.1O2 (NCM811) for lithium ion batteries (LIBs) is synthesized. To improve the performance of this NCM811 material, Al2O3, ZrO2 and LBO (Li2O-2B2O3) are respectively used to coat it by a wet chemical method. The effects of Al2O3, ZrO2 and LBO thin coating layers (~20～200 nm) on the morphology, structure and electrochemical property of NCM811 are studied using XRD, SEM, TEM, XPS, and electrochemical measurements. Coin LIBs are assembled with the uncoated, Al2O3-coated, ZrO2-coated and LBO-coated NCM811 cathode materials for performance validation. The experiment results confirm that the charge-discharge specific capacity, Coulomb efficiency, water absorption stability, cycle characteristics and resistance stability of the NCM811 cathode material can be significantly improved by coating it with LBO particularly. Therefore, the surface coating to the particles of cathode materials using LBO is expected to be an effective and practical modification method to improve the electrochemical performance of LIBs.
Highlights
Electrochemical energy technologies, such as lithium-ion batteries, metal-air batteries, fuel cell, and water electrolysis, etc., have been recognized as one type of the most reliable and efficient options for clean and sustainable electricity energy storage and conversion (Khan et al, 2018; Wang et al, 2018; Zhang H. et al, 2018; Zhang L. et al, 2018)
Al2O3, ZrO2, and LBO are used to coat on NCM811 to form the coated cathode materials by a wet chemical method
The effects of Al2O3, ZrO2, and LBO coatings on the morphologies, structures, compositions, and electrochemical properties of NCM811 are studied by both the physical characterization and electrochemical measurements
Summary
Electrochemical energy technologies, such as lithium-ion batteries, metal-air batteries, fuel cell, and water electrolysis, etc., have been recognized as one type of the most reliable and efficient options for clean and sustainable electricity energy storage and conversion (Khan et al, 2018; Wang et al, 2018; Zhang H. et al, 2018; Zhang L. et al, 2018). LBO coating has shown a good ionic conductivity, which makes the coated cathode materials more conducive to lithium ions, leading to better electrochemical properties It has been reported in the literature that the surface coatings of LBO glass on LiNi0.5Mn1.5O4 (Lim et al, 2014), LiNi0.5Co0.2Mn0.3O2 (Song et al, 2019), and LiMn2O4 (Chan et al, 2005) cathodes can make remarkable improvements in charge-discharge behavior, cycle-life and other electrochemical properties. The effects of different coatings on the electrochemical properties of NCM811 are studied by testing the charge/discharge curves and Coulomb efficiencies, cycle performance and DC resistances of the corresponding coin LIBs. According to a molar ratio of 8:1:1 (Ni: Co: Mn metal ions), nickel sulfate (NiSO4·6H2O), cobalt sulfate (CoSO4·7H2O), manganese sulfate (MnSO4·2H2O) were, respectively, weighed and added into deionized water and stirred evenly, and a mixed solution with a total concentration of metal ions of 0.5 mol/L was prepared. The discharge capacity of 0.1–0.5 wt% LBO-coated Li1+xMn2O4 was 122.5, 116.2, and 111.4 mAh g−1 in the initial cycle, and remained 86 ∼ 93% of its origin value after 20 cycles
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