Polyvinyl alcohol （PVA）-sodium polyacrylate （PAAS）-KOH-H2O alkaline polymer electrolyte film with high ionic conductivity was prepared by a solution-casting method. Polymer Ni（OH）2/activated carbon （AC） hybrid...Polyvinyl alcohol （PVA）-sodium polyacrylate （PAAS）-KOH-H2O alkaline polymer electrolyte film with high ionic conductivity was prepared by a solution-casting method. Polymer Ni（OH）2/activated carbon （AC） hybrid supercapacitors with different electrode active material mass ratios （positive to negative） were fabricated using this alkaline polymer electrolyte, nickel hydroxide positive electrodes, and AC negative electrodes. Galvanostatic charge/ discharge and electrochemical impedance spectroscopy （EIS） methods were used to study the electrochemical performance of the capacitors, such as charge/discharge specific capacitance, rate charge/discharge ability, and charge/discharge cyclic stability. Experimental results showed that with the decreasing of active material mass ratio m（Ni（OH）2）/m（AC）, the charge/discharge specific capacitance increases, but the rate charge/discharge ability and the charge/discharge cyclic stability decrease.展开更多
Lithium-sulfur batteries are emerging as sustainable replacements for current lithium-ion batteries.The commercial viability of this novel type of battery is still under debate due to the extensive use of highly react...Lithium-sulfur batteries are emerging as sustainable replacements for current lithium-ion batteries.The commercial viability of this novel type of battery is still under debate due to the extensive use of highly reactive lithium-metal anodes and the complex electrochemistry of the sulfur cathode.In this research,a novel sulfur-based battery has been proposed that eliminates the need for metallic lithium anodes and other critical raw materials like cobalt and graphite,replacing them with biomass-derived materials.This approach presents numerous benefits,encompassing ample availability,cost-effectiveness,safety,and environmental friendliness.In particular,two types of biochar-based anode electrodes(non-activated and activated biochar)derived from spent common ivy have been investigated as alternatives to metallic lithium.We compared their structural and electrochemical properties,both of which exhibited good compatibility with the typical electrolytes used in sulfur batteries.Surprisingly,while steam activation results in an increased specific surface area,the non-activated ivy biochar demonstrates better performance than the activated biochar,achieving a stable capacity of 400 mA h g^(−1)at 0.1 A g^(−1)and a long lifespan(>400 cycles at 0.5 A g^(−1)).Our results demonstrate that the presence of heteroatoms,such as oxygen and nitrogen positively affects the capacity and cycling performance of the electrodes.This led to increased d-spacing in the graphitic layer,a strong interaction with the solid electrolyte interphase layer,and improved ion transportation.Finally,the non-activated biochar was successfully coupled with a sulfur cathode to fabricate lithium-metal-free sulfur batteries,delivering a specific energy density of~600 Wh kg^(−1).展开更多
The structure and characteristic of carbon materials have a direct influence on the electrochemical performance of sulfur-carbon composite electrode materials for lithium-sulfur battery. In this paper, sulfur composit...The structure and characteristic of carbon materials have a direct influence on the electrochemical performance of sulfur-carbon composite electrode materials for lithium-sulfur battery. In this paper, sulfur composite has been synthesized by heating a mixture of elemental sulfur and activated carbon, which is characterized as high specific surface area and microporous structure. The composite, contained 70% sulfur, as cathode in a lithium cell based on organic liquid electrolyte was tested at room temperature. It showed two reduction peaks at 2.05 V and 2.35 V, one oxidation peak at 2.4 V during cyclic voltammogram test. The initial discharge specific capacity was 1180.8 mAh g-1 and the utilization of electrochemically active sulfur was about 70.6% assuming a complete reaction to the product of Li2S. The specific capacity still kept as high as 720.4 mAh g^-1 after 60 cycles retaining 61% of the initial discharge capacity.展开更多
In this study, activated carbon was prepared by the potassium hydroxide activation method with flax residues as raw materials. High-quality activated carbon was prepared by single factor and orthogonal experiments. Io...In this study, activated carbon was prepared by the potassium hydroxide activation method with flax residues as raw materials. High-quality activated carbon was prepared by single factor and orthogonal experiments. Iodine adsorption and methylene blue adsorption were used as performance indicators. As prepared activated carbon was characterized by XRD, XPS and SEM. The results showed that the optimized electrode material was prepared under an impregnation ratio of 1:2, activation temperature of 800°C and activation time of 100 min. The yield of activated carbon was 49.48%, the iodine value was 1667.13 mg/g and the methylene blue value was 429 mg/g. The specific surface area measured by the automatic porosity analyzer is 1221 m<sup>2</sup>/g, and the mass-specific capacitance is 215.7 F/g under current density of 0.1 A/g.展开更多
Using lignite-based hypercoal as raw material, KOH as activator and CuO as microwave absorber, we prepared hypercoal-based activated carbons by microwave-assisted activation. The pore structure and the electrochemical...Using lignite-based hypercoal as raw material, KOH as activator and CuO as microwave absorber, we prepared hypercoal-based activated carbons by microwave-assisted activation. The pore structure and the electrochemical performance of the activated carbons were tested, and the effects of adding CuO in the activation reaction process were also investigated. The activated carbons prepared were characterized by nitrogen adsorption-desorption, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The specific surface area and mesoporous ratio of the hypercoal-based activated carbon are 1257 m2/g and 55.4%, respectively. When the activated carbons are used as the electrode materials, the specific capacitance reaches 309 F/g in 3 M KOH electrolyte. In comparison with those prepared without CuO absorber, the specific capacitance increases by 11.6%. It was proved that the addition of microwave absorber in microwave-assisted activation was a low-cost method for rapidly preparing activated carbon, and it could effectively promote the development of the pore structure and improve its electrochemical performance.展开更多
In this article, a facile two-step activation method, coupled with phosphoric acid(H3PO4)-assisted pretreatment and followed KOH activation,was reported for constructing hierarchical porous carbon(HPC) materials deriv...In this article, a facile two-step activation method, coupled with phosphoric acid(H3PO4)-assisted pretreatment and followed KOH activation,was reported for constructing hierarchical porous carbon(HPC) materials derived from lignin. The introduction of H3PO4, cross-linked with lignin sources generated phosphate(and/or polyphosphate) ester groups throughout the lignin structure, which endowed the pre-activated intermediate char(IC)with a hierarchical porous structure. Such phosphate esters contributed to the multi-scale pore structure within the pre-activated IC, which was beneficial for the uniform distribution and impregnation of subsequent KOH activators,thus leading to the formation of HPC materials. The as-prepared HPC exhibited a large specific surface area(SSA) of 1345.1 m^2/g, which ensures the accessibility of the ion diffusion pathways. The supercapacitors integrated with HPC delivered a high specific capacitance of 241 F/g(in a threeelectrode system) and outstanding rate capability with an 80.9% capacitance retention from 0.5 A/g to an ultra-high current density of 50 A/g.展开更多
基金Supported by Leading Academic Discipline Project of Shanghai Municipal Education Commission (J50102)
文摘Polyvinyl alcohol （PVA）-sodium polyacrylate （PAAS）-KOH-H2O alkaline polymer electrolyte film with high ionic conductivity was prepared by a solution-casting method. Polymer Ni（OH）2/activated carbon （AC） hybrid supercapacitors with different electrode active material mass ratios （positive to negative） were fabricated using this alkaline polymer electrolyte, nickel hydroxide positive electrodes, and AC negative electrodes. Galvanostatic charge/ discharge and electrochemical impedance spectroscopy （EIS） methods were used to study the electrochemical performance of the capacitors, such as charge/discharge specific capacitance, rate charge/discharge ability, and charge/discharge cyclic stability. Experimental results showed that with the decreasing of active material mass ratio m（Ni（OH）2）/m（AC）, the charge/discharge specific capacitance increases, but the rate charge/discharge ability and the charge/discharge cyclic stability decrease.
基金supported by the Special Research Fund(BOF23PD03,P.Salimi)the Research Foundation Flanders(FWO SB-1S92022N,W.Vercruysse).
文摘Lithium-sulfur batteries are emerging as sustainable replacements for current lithium-ion batteries.The commercial viability of this novel type of battery is still under debate due to the extensive use of highly reactive lithium-metal anodes and the complex electrochemistry of the sulfur cathode.In this research,a novel sulfur-based battery has been proposed that eliminates the need for metallic lithium anodes and other critical raw materials like cobalt and graphite,replacing them with biomass-derived materials.This approach presents numerous benefits,encompassing ample availability,cost-effectiveness,safety,and environmental friendliness.In particular,two types of biochar-based anode electrodes(non-activated and activated biochar)derived from spent common ivy have been investigated as alternatives to metallic lithium.We compared their structural and electrochemical properties,both of which exhibited good compatibility with the typical electrolytes used in sulfur batteries.Surprisingly,while steam activation results in an increased specific surface area,the non-activated ivy biochar demonstrates better performance than the activated biochar,achieving a stable capacity of 400 mA h g^(−1)at 0.1 A g^(−1)and a long lifespan(>400 cycles at 0.5 A g^(−1)).Our results demonstrate that the presence of heteroatoms,such as oxygen and nitrogen positively affects the capacity and cycling performance of the electrodes.This led to increased d-spacing in the graphitic layer,a strong interaction with the solid electrolyte interphase layer,and improved ion transportation.Finally,the non-activated biochar was successfully coupled with a sulfur cathode to fabricate lithium-metal-free sulfur batteries,delivering a specific energy density of~600 Wh kg^(−1).
基金supported by the National Key Program for Basic Research of China(No. 2009CB220100)the National 863 Program(No.2007AA03Z226)
文摘The structure and characteristic of carbon materials have a direct influence on the electrochemical performance of sulfur-carbon composite electrode materials for lithium-sulfur battery. In this paper, sulfur composite has been synthesized by heating a mixture of elemental sulfur and activated carbon, which is characterized as high specific surface area and microporous structure. The composite, contained 70% sulfur, as cathode in a lithium cell based on organic liquid electrolyte was tested at room temperature. It showed two reduction peaks at 2.05 V and 2.35 V, one oxidation peak at 2.4 V during cyclic voltammogram test. The initial discharge specific capacity was 1180.8 mAh g-1 and the utilization of electrochemically active sulfur was about 70.6% assuming a complete reaction to the product of Li2S. The specific capacity still kept as high as 720.4 mAh g^-1 after 60 cycles retaining 61% of the initial discharge capacity.
文摘In this study, activated carbon was prepared by the potassium hydroxide activation method with flax residues as raw materials. High-quality activated carbon was prepared by single factor and orthogonal experiments. Iodine adsorption and methylene blue adsorption were used as performance indicators. As prepared activated carbon was characterized by XRD, XPS and SEM. The results showed that the optimized electrode material was prepared under an impregnation ratio of 1:2, activation temperature of 800°C and activation time of 100 min. The yield of activated carbon was 49.48%, the iodine value was 1667.13 mg/g and the methylene blue value was 429 mg/g. The specific surface area measured by the automatic porosity analyzer is 1221 m<sup>2</sup>/g, and the mass-specific capacitance is 215.7 F/g under current density of 0.1 A/g.
基金Funded by the National Natural Science Foundation of China(No.51874136)Natural Science Foundation of Hebei Province(No.B2017209240)。
文摘Using lignite-based hypercoal as raw material, KOH as activator and CuO as microwave absorber, we prepared hypercoal-based activated carbons by microwave-assisted activation. The pore structure and the electrochemical performance of the activated carbons were tested, and the effects of adding CuO in the activation reaction process were also investigated. The activated carbons prepared were characterized by nitrogen adsorption-desorption, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The specific surface area and mesoporous ratio of the hypercoal-based activated carbon are 1257 m2/g and 55.4%, respectively. When the activated carbons are used as the electrode materials, the specific capacitance reaches 309 F/g in 3 M KOH electrolyte. In comparison with those prepared without CuO absorber, the specific capacitance increases by 11.6%. It was proved that the addition of microwave absorber in microwave-assisted activation was a low-cost method for rapidly preparing activated carbon, and it could effectively promote the development of the pore structure and improve its electrochemical performance.
基金supported by the Fundamental Research Funds for the Central Universities(BLX201823)Beijing Forestry University Outstanding Young Talent Cultivation Project(2019JQ03017)Beijing Municipal Natural Science Foundation(6182031).
文摘In this article, a facile two-step activation method, coupled with phosphoric acid(H3PO4)-assisted pretreatment and followed KOH activation,was reported for constructing hierarchical porous carbon(HPC) materials derived from lignin. The introduction of H3PO4, cross-linked with lignin sources generated phosphate(and/or polyphosphate) ester groups throughout the lignin structure, which endowed the pre-activated intermediate char(IC)with a hierarchical porous structure. Such phosphate esters contributed to the multi-scale pore structure within the pre-activated IC, which was beneficial for the uniform distribution and impregnation of subsequent KOH activators,thus leading to the formation of HPC materials. The as-prepared HPC exhibited a large specific surface area(SSA) of 1345.1 m^2/g, which ensures the accessibility of the ion diffusion pathways. The supercapacitors integrated with HPC delivered a high specific capacitance of 241 F/g(in a threeelectrode system) and outstanding rate capability with an 80.9% capacitance retention from 0.5 A/g to an ultra-high current density of 50 A/g.
