The co-precipitation derived LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 cathode material was modified by a coating layer of TiP_2O_7 through an ethanol-based process. The TiP_2O_7-coated LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 is charac...The co-precipitation derived LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 cathode material was modified by a coating layer of TiP_2O_7 through an ethanol-based process. The TiP_2O_7-coated LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 is characterized by Xray diffraction analysis, scanning electron microscopy and transmission electron microscopy to investigate the microstructure and morphology. The differential scanning calorimetry was employed to confirm the improved thermal stability. The electrochemical properties were evaluated by the constant-current charge/discharge tests. The TiP_2O_7 coating layer is effectively suppressing the structural degradation and ameliorating the surface status of LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 particles, and the intrinsic rhombohedral layered structure of TiP_2O_7-coated LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 was well maintained during the long-term cycling process, while the surface structure of pristine LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 was degraded from rhombohedral R3 m layered structure to cubic rock-salt structure. The charged state Ni^(4+) ions will easily transform into Ni^(2+) when the electrolytes oxidized at the interface of cathode/electrolytes and formed the cubic rock-salt NiO type structure, and the cubic rock-salt structure without electrochemical activity on the surface of LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 particles will finally accelerate capacity fading. The thermal stability and cyclic performances of the LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 electrode were remarkably improved by TiP_2O_7 coating, the total amount of heat release corresponding to the intensity of thermal runaway were 1075.5 and 964.6 J/g for pristine LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 and TiP_2O_7-coated LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 respectively, the pouch shaped full cells that employed TiP 2 O7-coated LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 as cathode were able to perform more than 2200 cycles at 25 ℃ and more than 1000 cycles at 45 ℃ before the capacity retention fading to 80%.展开更多
Waste resource utilization of petroleum coke is crucial for achieving global carbon emission reduction.Herein,a series of N-doped microporous carbons were fabricated from petroleum coke using a one-pot synthesis metho...Waste resource utilization of petroleum coke is crucial for achieving global carbon emission reduction.Herein,a series of N-doped microporous carbons were fabricated from petroleum coke using a one-pot synthesis method.The as-prepared samples had a large specific surface area(up to 2512 m^(2)/g),a moderate-high N content(up to 4.82 at.%),and high population(55%)of ultra-micropores(<0.7 nm).Regulating the N content and ultra-microporosity led to efficient CO_(2)adsorption and separation.At ambient pressure,the optimal N-doped petroleum coke-based microporous carbon exhibited the highest CO_(2)uptake of 4.25 mmol/g at 25℃ and 6.57 mmol/g at 0℃.These values are comparable or even better than those of numerous previously reported adsorbents prepared by multistep synthesis,primarily due to the existence of ultra-micropores.The sample exhibited excellent CO_(2)/N_(2)selectivity at 25℃ owing to the abundant basic pyridinic and pyrrolic N species;and showed superior CO_(2)adsorption-desorption cycling performance,which was maintained at 97% after 10 cycles at 25℃.Moreover,petroleum coke-based microporous carbon,with a considerably high specific surface area and hierarchical pore structure,exhibited excellent electrochemical performance over the N-doped sample,maintaining a favorable specific capacitance of 233.25F/g at 0.5 A/g in 6 mol/L KOH aqueous electrolyte.This study provides insight into the influence of N-doping on the porous properties of petroleum coke-based carbon.Furthermore,the as-prepared carbons were found to be promising adsorbents for CO_(2)adsorption,CO_(2)/N_(2)separation and electrochemical application.展开更多
Miscible carbon dioxide(CO_(2))flooding is a well-established and promising enhanced oil recovery(EOR)technique whereby residual oil is recovered by mixing with injected CO_(2)gas.However,CO_(2),being very light and l...Miscible carbon dioxide(CO_(2))flooding is a well-established and promising enhanced oil recovery(EOR)technique whereby residual oil is recovered by mixing with injected CO_(2)gas.However,CO_(2),being very light and less viscous than reservoir crude oil,results in inefficient sweep efficiency.Extensive research is ongoing to improve CO_(2)mobility control such as the development and generation of CO_(2)/water foams.The long-term stability of foam during the period of flooding is a known issue and must be considered during the design stage of any CO_(2)foam flooding project.The foam stability can be improved by adding surfactants as stabilizers,but surfactants generated foams have generally a shorter life because of an unstable interface.Furthermore,surfactants are prone to higher retention and chemical degradation in the porous media,particularly under harsh reservoir conditions.Research has shown that nanoparticles(NPs)can act as an excellent stabilizing agent for CO_(2)/water foams owing to their surface chemistry and high adsorption energy.The foams generated using NPs are more stable and provide better mobility control compared to surfactant-stabilized foams.One limitation of using NPs as foam stabilizers is their colloidal stability which limits the use of low-cost NPs.Combining surfactants and NPs for CO_(2)foam stabilization is a novel approach and has gained interest among researchers in recent years.Surfactants improve the dispersion of NPs in the aqueous phase and minimize particle aggregation.NPs on the other hand create a stable barrier at the CO_(2)/water interface with the help of surfactants,thus generating highly stable and viscous foams.This paper presents a comprehensive review of the basic principles and applications of stabilized CO_(2)foams.A brief overview of CO_(2)foam flooding is discussed first,followed by a review of standalone surfactant-stabilized and NPs-stabilized CO_(2)/water foams.The application of hybrid surfactant-NPs stabilized CO_(2)foams is then presented and areas requiring further investigation are highlighted.This review provides an insight into a novel approach to stabilize CO_(2)/water foams and the effectiveness of the method as proved by various studies.展开更多
基金supported by the National Natural Science Foundation of China (No. 51372178)the Natural Science Foundation for Distinguished Young Scholars of Hubei Province of China (No. 2013CFA021)
文摘The co-precipitation derived LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 cathode material was modified by a coating layer of TiP_2O_7 through an ethanol-based process. The TiP_2O_7-coated LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 is characterized by Xray diffraction analysis, scanning electron microscopy and transmission electron microscopy to investigate the microstructure and morphology. The differential scanning calorimetry was employed to confirm the improved thermal stability. The electrochemical properties were evaluated by the constant-current charge/discharge tests. The TiP_2O_7 coating layer is effectively suppressing the structural degradation and ameliorating the surface status of LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 particles, and the intrinsic rhombohedral layered structure of TiP_2O_7-coated LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 was well maintained during the long-term cycling process, while the surface structure of pristine LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 was degraded from rhombohedral R3 m layered structure to cubic rock-salt structure. The charged state Ni^(4+) ions will easily transform into Ni^(2+) when the electrolytes oxidized at the interface of cathode/electrolytes and formed the cubic rock-salt NiO type structure, and the cubic rock-salt structure without electrochemical activity on the surface of LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 particles will finally accelerate capacity fading. The thermal stability and cyclic performances of the LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 electrode were remarkably improved by TiP_2O_7 coating, the total amount of heat release corresponding to the intensity of thermal runaway were 1075.5 and 964.6 J/g for pristine LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 and TiP_2O_7-coated LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 respectively, the pouch shaped full cells that employed TiP 2 O7-coated LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 as cathode were able to perform more than 2200 cycles at 25 ℃ and more than 1000 cycles at 45 ℃ before the capacity retention fading to 80%.
基金supported by the Science and Technology Program of Guangzhou,China(No.202002020020)the National Natural Science Foundation of China(Nos.51808227,51878292)the Fundamental Research Funds for the Central Universities(No.2020ZYGXZR015)。
文摘Waste resource utilization of petroleum coke is crucial for achieving global carbon emission reduction.Herein,a series of N-doped microporous carbons were fabricated from petroleum coke using a one-pot synthesis method.The as-prepared samples had a large specific surface area(up to 2512 m^(2)/g),a moderate-high N content(up to 4.82 at.%),and high population(55%)of ultra-micropores(<0.7 nm).Regulating the N content and ultra-microporosity led to efficient CO_(2)adsorption and separation.At ambient pressure,the optimal N-doped petroleum coke-based microporous carbon exhibited the highest CO_(2)uptake of 4.25 mmol/g at 25℃ and 6.57 mmol/g at 0℃.These values are comparable or even better than those of numerous previously reported adsorbents prepared by multistep synthesis,primarily due to the existence of ultra-micropores.The sample exhibited excellent CO_(2)/N_(2)selectivity at 25℃ owing to the abundant basic pyridinic and pyrrolic N species;and showed superior CO_(2)adsorption-desorption cycling performance,which was maintained at 97% after 10 cycles at 25℃.Moreover,petroleum coke-based microporous carbon,with a considerably high specific surface area and hierarchical pore structure,exhibited excellent electrochemical performance over the N-doped sample,maintaining a favorable specific capacitance of 233.25F/g at 0.5 A/g in 6 mol/L KOH aqueous electrolyte.This study provides insight into the influence of N-doping on the porous properties of petroleum coke-based carbon.Furthermore,the as-prepared carbons were found to be promising adsorbents for CO_(2)adsorption,CO_(2)/N_(2)separation and electrochemical application.
基金the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan for supporting this research through the Grant No.AP09562433.
文摘Miscible carbon dioxide(CO_(2))flooding is a well-established and promising enhanced oil recovery(EOR)technique whereby residual oil is recovered by mixing with injected CO_(2)gas.However,CO_(2),being very light and less viscous than reservoir crude oil,results in inefficient sweep efficiency.Extensive research is ongoing to improve CO_(2)mobility control such as the development and generation of CO_(2)/water foams.The long-term stability of foam during the period of flooding is a known issue and must be considered during the design stage of any CO_(2)foam flooding project.The foam stability can be improved by adding surfactants as stabilizers,but surfactants generated foams have generally a shorter life because of an unstable interface.Furthermore,surfactants are prone to higher retention and chemical degradation in the porous media,particularly under harsh reservoir conditions.Research has shown that nanoparticles(NPs)can act as an excellent stabilizing agent for CO_(2)/water foams owing to their surface chemistry and high adsorption energy.The foams generated using NPs are more stable and provide better mobility control compared to surfactant-stabilized foams.One limitation of using NPs as foam stabilizers is their colloidal stability which limits the use of low-cost NPs.Combining surfactants and NPs for CO_(2)foam stabilization is a novel approach and has gained interest among researchers in recent years.Surfactants improve the dispersion of NPs in the aqueous phase and minimize particle aggregation.NPs on the other hand create a stable barrier at the CO_(2)/water interface with the help of surfactants,thus generating highly stable and viscous foams.This paper presents a comprehensive review of the basic principles and applications of stabilized CO_(2)foams.A brief overview of CO_(2)foam flooding is discussed first,followed by a review of standalone surfactant-stabilized and NPs-stabilized CO_(2)/water foams.The application of hybrid surfactant-NPs stabilized CO_(2)foams is then presented and areas requiring further investigation are highlighted.This review provides an insight into a novel approach to stabilize CO_(2)/water foams and the effectiveness of the method as proved by various studies.
