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![]() ![]() After stirring for 15 min, clear solution (25 mL) is separated by vacuum filtering. 2.5 g of NCM91 powder is soaked into 50 mL deionized water. The residual lithium (LiOH and Li 2CO 3) amounts were obtained via titration method. The electrochemical impedance spectroscopy (EIS) was conducted using the electrochemical interface and a frequency response analyzer (Bio-Logic, VSP-300) in the frequency range of 10 −2 to 10 6 Hz. The electrochemical performances were measured using an electrochemical equipment (TOSCAT-3100, Toyo system). The structural properties of the NCM91 particles were measured using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM). All coin cells were assembled in argon-gas-filled glove box. The 2032 coin cells were assembled with Li metal disc as anode, 1 M LiPF 6 in ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate (EC:DMC:EMC 1:1:1, v/v/v/) as electrolyte and polyethylene was used as a separator. It was casted on aluminum foil and then dried at 120 ☌ to remove the NMP solvent and then the aluminum foil was pressed. N-Methyl pyrrolidone (NMP) solvent was then added to form slurry. The cathodes were prepared using the following process: to fabricate a slurry, active material, conductive carbon black binder (Super P) and polyvinylidene fluoride (PVDF) were mixed in the weight ratio of 96:2:2. The heating and cooling rates for sintering processes were fixed at 10 ☌ min −1. The mixture was calcined at 500 ☌ for 5 h and then sintered at 640~740 ☌ for 15 h in air. H 2O was mixed with as-prepared NCM91 in a molar ratio 1.05: 1.Also, NaOH and NH 4OH solution were also used as a chelating agent. Also the relationship between the sintering temperatures and the electrochemical performances is investigated.įor higher energy density, spherical precursor NCM91 with a bimodal size distribution was prepared by co-precipitation methodeusing NiSO 4♶H 2O, CoSO 4♷H 2O and MnSO 4 In this paper, we report the synthesis of LiNi 0.91Co 0.06Mn 0.03O 2 (denoted as NCM91) cathode materials at various sintering temperatures. It is reported that crystallinity, morphology and structural stability, influenced by the sintering temperatures, all play an important role in the electrochemical performances, especially for Ni-rich cathode 11. (iii) disintegration derived from mechanical which stress deteriorate the long term stability by consuming active lithium 11, 12. (ii) undesirable materials on the cathode surface from reaction with transition metal ions and electrolyte cause performance decay. ![]() There are three main reasons for performance degradation of Ni-rich cathode: (i) cation disorder decreases the capacity, closely related to phase transformation of layered structure to a spinel or rock-salt structure. Therefore, the future of NCM for high energy LIBs strongly depends on Ni-rich NCM materials. Li(Ni 1/3Co 1/3Mn 1/3)O 2 has been successfully commercialized as a battery cathode, researches on Ni-rich NCM (LiNi xCo yMn 1−x−yO 2, x > 0.5) have been spotlighted due to its superior capacity (>200 mAh/g, at 4.6 V vs. Among the various cathode candidates, layer structured Li(Ni,Co,Mn)O 2 (NCM) has been regarded as the most attractive alternative to LIBs owing to relatively modest volume change (LiCoO 2), high specific capacity (LiNiO 2) and good thermal stability (LiMn 2O 4) 7, 8, 9. The energy density of LIBs is mainly determined by the cathode since the commercial carbonaceous anode potential is ~0 V 6. Thus, LIBs are widely used in electric vehicles (EVs), hybrid electric vehicles (HEVs), golf carts, electric bicycles, portable devices and so on. In the case of ECs, various attempts have been made to improve the energy density however, it is difficult to realize the high energy density of the LIBs (~200 Wh/kg) which is the greatest advantage for energy storage application 5. The importance of energy storage devices is rapidly increasing, and various energy storage devices such as lithium ion batteries (LIBs), sodium-ion battery, electrochemical capacitors (ECs) and hybrid supercapacitors are being studied 1, 2, 3, 4. ![]()
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