LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA) cathode material was usually prepared with Ni 2+ , Co 2+ , Al 3+ co-precipitation method using NaOH/NH 3 ·H 2 O aqueous solution with strictly control of liquid feeding rate and pH value. In this contribution, a facile method was proposed to co-precipitate Ni 2+ , Co 2+ , Al 3+ for synthesizing NCA using (NH 4 ) 2 C 2 O 4 ·2H 2 O as precipitant without control of pH and liquid feeding rate. The impact of reagents (sulfate reagents, nitrate reagents, chloride reagents, acetate reagents) on morphology, micro-structure and final electrochemical performances of NCA were systematically studied. It was suggested that sulfate reagents are suitable for synthesizing NCA. Furthermore, an optimum synthesis route was further selected for mass production. The NCA delivered reversible specific capacity of about 200 mAh g −1 , 191 mAh g −1 , 177 mAh g −1 , 153 mAh g −1 , 132 mAh g −1 , 115 mAh g −1 , 105 mAh g −1 and 94 mAh g −1 at 0.1 C, 0.5 C, 1 C, 2 C, 3 C, 4 C, 5 and 6 C, respectively. Considering the facile and economical synthesis method of precursor, this work can be a footstone for advancing the practical application of NCA cathodes.
In this work, hydrothermal technique combined with KOH activation were employed to develop a series of porous carbons (NPCK- x ) using tobacco stem as a low-cost carbon source and (NH 4 ) 2 C 2 O 4 as a novel nitrogen-doping agent. Physicochemical properties of NPCK- x were characterized by Brunauer-Emmett-Teller, field emission scanning electron microscopy, X-ray diffraction, Raman microscope, elemental analysis, and X-ray photoelectron spectroscopy. Results showed that the NPCK- x samples possessed large surface areas (maximum: 2875 m 2 /g), hierarchical porous structures, and high degree of disorder. N-containing functional groups decomposed during activation process, which could be the dominant reason for appearance of abundant mesopores and well-developed pore structure. Dynamic chlorobenzene adsorption experiments demonstrated that carbon materials with (NH 4 ) 2 C 2 O 4 modification exhibited higher adsorption capacity (maximum: 1053 mg/g) than those without modification (maximum: 723 mg/g). The reusability studies of chlorobenzene indicated that the desorption efficiency of (NH 4 ) 2 C 2 O 4 modified porous carbon reached 90.40% after thermal desorption at 100°C under N 2 atmosphere. Thomas model fitting results exhibited that the existence of mesopores accelerated the diffusion rate of chlorobenzene in porous carbon. Moreover, Grand Canonical Monte Carlo simulation was conducted to verify that micropores with pore sizes of 1.2–2 nm of the optimized porous carbon were the best adsorption sites for chlorobenzene and mesopores with pore sizes of 2–5 nm were also highly active sites for chlorobenzene adsorption.
Typical organic pollutants from coal-combustion flue gas such as volatile organic compounds (VOCs) need to be effectively controlled. This work synthesized a series of nitrogen-doped hierarchical porous carbons (NHPCs) by one-step activation with various proportions of cellulose, (NH 4 ) 2 C 2 O 4 and KHCO 3 /NaHCO 3 . The NHPCs have a high specific surface area and pore volume up to 2816 m 2 /g and 1.413 cm 3 /g as well as a hierarchical porous structure with micro-meso-macropores distribution. The dynamic adsorption tests of toluene at 600 ppm showed that NHPCs have a high adsorption capacity up to 585 mg/g (NHPC(K)131), this was about 3 times more than that of AC (208 mg/g), and is a better absorbent compared to many other carbon adsorbents. The porous characteristics and toluene adsorption properties of NHPCs improved along with the fluctuation of the proportions of raw materials and active agents. The micropore size of the material is the main factor that affecting the toluene adsorption capacity. The analysis of toluene dynamic adsorption breakthrough curves revealed that NHPCs had great toluene adsorption kinetics with high adsorption rate constants and short mass transfer zone. The excellent toluene adsorption kinetics of NHPCs can be attributed to the hierarchical porous structure. The abundant 2–10 nm mesopores and macropores of NHPCs act as mass transfer channels for toluene molecules. The XPS analysis showed that the NHPCs have nitrogen doping up to 6.71% (NHPC(Na)161) and they effectively promote toluene adsorption. The nitrogen doping mechanism can be attributed to the reactions between cellulose pyrolysis substances and NH 3 which decomposed from (NH 4 ) 2 C 2 O 4 . Moreover, the pore forming reactivity of KHCO 3 is better than that of NaHCO 3 in the NHPCs activation process.
危险品化学品经营许可证（带存储）