The Experts below are selected from a list of 134451 Experts worldwide ranked by ideXlab platform
Cheung Mak - One of the best experts on this subject based on the ideXlab platform.
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Bi-functional sulphonate-coupled reduced graphene oxide as an efficient dopant for a conducting polymer with enhanced Electrochemical Performance
Journal of Materials Chemistry C, 2020Co-Authors: Lingyin Meng, Frida Dagsgård, Anthony Turner, Cheung MakAbstract:The rapidly emerging field of organic bioelectronics has witnessed the wide use of conducting polymers (CPs) to fabricate advanced chemically modified electrodes (CMEs) for biosensors and biomedical devices. The Electrochemical Performance of the CPs in such devices is closely related to the quality and physiochemical nature of the dopants. A bi-functional graphene oxide derivative with high reduction degree and negatively-charged sulphonate functionality, i.e. sulphonate-coupled reduced graphene oxide (S-RGO), was developed and used as an efficient dopant for a CP with enhanced Electrochemical Performance. The S-RGO was synthesised via a facile one-pot hydrothermal reaction using 4-hydrazinobenzosulphonic acid (4-HBS) as reductant and sulphonate precursor simultaneously. The resulting S-RGO possesses high aqueous dispersion stability (more than 6 months), high electrical conductivity (1493.0 S m−1) and sulphonate functionality. Due to these specific properties, S-RGO demonstrated improved electropolymerisation efficiency for poly(3,4-ethylenedioxythiophene) (PEDOT) proving an effective dopant for the preparation of a PEDOT:S-RGO film (5 mC) with faster polymerisation time (37 s) compared to the conventional 2D dopants GO (PEDOT:GO, 129 s) and RGO (PEDOT:RGO, 66 s). The resulting PEDOT:S-RGO appeared as a homogenous film with uniformly distributed S-RGO dopant, low equivalent series resistance and low charge transfer resistance. Moreover, the Electrochemical transduction Performance of the PEDOT:S-RGO interface was evaluated with 4 different analytes, including ferric/ferrocyanide redox probe, dopamine, nicotinamide adenine dinucleotide and hydrogen peroxide. As a result of the synergistic effect of S-RGO and PEDOT, the PEDOT:S-RGO demonstrated enhanced Electrochemical Performance with respect to faster electrode kinetics (smaller ΔEp), ∼2 and ∼4 times increased current responses, and lower peak potentials compared to PEDOT:GO and PEDOT:RGO. This bi-functional S-RGO dopant combined the advantages of conventional GO and RGO to deliver sulphonate functionality and high conductivity for the preparation of advanced PEDOT interface with improved Electrochemical Performance, that could potentially be applied for applications in Electrochemical sensors, biosensors and bioelectronic devices.
Quanqi Chen - One of the best experts on this subject based on the ideXlab platform.
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improvement in Electrochemical Performance of na3v2 po4 3 c cathode material for sodium ion batteries by k ca co doping
Electrochimica Acta, 2018Co-Authors: Hua Cheng, Qing Zhu, Xinmei Zhang, Jianwen Yang, Quanqi ChenAbstract:Abstract It is still a great challenge to improve the diffusion dynamics of Na+ throughout the Na3V2(PO4)3, one of the most promising cathodes for sodium ion batteries. In this work, we present a facile doping strategy to tackle this problem by co-doping the Na+ with K+ and Ca2+. Na3-3xKxCaxV2(PO4)3/C (x = 0, 0.05, 0.07 and 0.09) composites are prepared by a sol-gel method combined with freeze-drying and high-temperature calcination processes, and the composites are characterized by XRD, XPS, SEM, TEM and Electrochemical measurements. The results indicate that co-substitution of K+ and Ca2+ for Na in Na3V2(PO4)3 enlarges the cell volume of Na3V2(PO4)3 and is beneficial for improving Electrochemical Performance. All co-doped Na3V2(PO4)3/C composites have better Electrochemical Performance than the pristine Na3V2(PO4)3/C composite. The optimal doping compositions are found to be Na2.79K0.07Ca0.07V2(PO4)3/C, displaying reversible capacities of 110.2, 92.7 and 83.6 mAh·g-1 at the current densities of 0.1, 1, and 10C (1180 mA·g-1), respectively, in the voltage range of 2.5–4.0 V. The Na2.79K0.07Ca0.07V2(PO4)3/C exhibits capacity retentions of 91% at 1C after 50 cycles and 83% at 10C after 150 cycles, while Na3V2(PO4)3/C composite displays capacity retentions of 88.5% at 1C after 50 cycles and 26.5% at 10C after 150 cycles, respectively. The improved Electrochemical Performance of co-doped Na3V2(PO4)3/C is ascribed to enhanced Na+ diffusion after the co-substitution of K+ and Ca2+ for Na in Na3V2(PO4)3/C.
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Electrochemical Performance of electrospun lifepo4 c submicrofibers composite cathode material for lithium ion batteries
Electrochimica Acta, 2012Co-Authors: Quanqi Chen, Xiaochang Qiao, Chang Peng, Tingting Zhang, Yaobin Wang, Xianyou WangAbstract:Abstract A LiFePO4/C submicrofibers composite was prepared by a facile electrospinning method using LiNO3, Fe(NO3)3·9H2O, NH4H2PO4, citric acid and poly(4-vinyl)pyridine (PVP) as raw materials, and its physical properties and Electrochemical Performance were investigated by X-ray diffraction (XRD) spectroscopy, scanning electron microscopy (SEM), transmission electron microscope (TEM), energy dispersive analysis of X-ray (EDAX), N2 adsorption/desorption measurement and Electrochemical tests. The crystal size of LiFePO4 fibers is about 30 nm calculated by Debye-Scherrer equation and the LiFePO4 nanofibers aggregate to LiFePO4/C submicrofibers composite with diameters of about 270–372 nm. The LiFePO4 submicrofibers are covered by an amorphous carbon layer with a thickness of about 2.6 nm and the LiFePO4/C submicrofibers composite with mesopores exhibits amazing high surface area of 167.729 m2 g−1. The LiFePO4/C submicrofibers composite displays high initial discharge capacities of 166 and 168 mAh g−1 and excellent cycle Performance at 0.1 C (17 mAh g−1) in the voltage range of 2.5–4.5 V at 25 and 55 °C, respectively. Even at high rate of 5 C, the LiFePO4/C submicrofibers composite delivers discharge capacities of 132 and 138 mAh g−1 and excellent cycle Performance at 25 and 55 °C, respectively. The results indicate that the electrospinning method is promising to prepare LiFePO4/C composite with high Electrochemical Performance.
Qing Zhu - One of the best experts on this subject based on the ideXlab platform.
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improvement in Electrochemical Performance of na3v2 po4 3 c cathode material for sodium ion batteries by k ca co doping
Electrochimica Acta, 2018Co-Authors: Hua Cheng, Qing Zhu, Xinmei Zhang, Jianwen Yang, Quanqi ChenAbstract:Abstract It is still a great challenge to improve the diffusion dynamics of Na+ throughout the Na3V2(PO4)3, one of the most promising cathodes for sodium ion batteries. In this work, we present a facile doping strategy to tackle this problem by co-doping the Na+ with K+ and Ca2+. Na3-3xKxCaxV2(PO4)3/C (x = 0, 0.05, 0.07 and 0.09) composites are prepared by a sol-gel method combined with freeze-drying and high-temperature calcination processes, and the composites are characterized by XRD, XPS, SEM, TEM and Electrochemical measurements. The results indicate that co-substitution of K+ and Ca2+ for Na in Na3V2(PO4)3 enlarges the cell volume of Na3V2(PO4)3 and is beneficial for improving Electrochemical Performance. All co-doped Na3V2(PO4)3/C composites have better Electrochemical Performance than the pristine Na3V2(PO4)3/C composite. The optimal doping compositions are found to be Na2.79K0.07Ca0.07V2(PO4)3/C, displaying reversible capacities of 110.2, 92.7 and 83.6 mAh·g-1 at the current densities of 0.1, 1, and 10C (1180 mA·g-1), respectively, in the voltage range of 2.5–4.0 V. The Na2.79K0.07Ca0.07V2(PO4)3/C exhibits capacity retentions of 91% at 1C after 50 cycles and 83% at 10C after 150 cycles, while Na3V2(PO4)3/C composite displays capacity retentions of 88.5% at 1C after 50 cycles and 26.5% at 10C after 150 cycles, respectively. The improved Electrochemical Performance of co-doped Na3V2(PO4)3/C is ascribed to enhanced Na+ diffusion after the co-substitution of K+ and Ca2+ for Na in Na3V2(PO4)3/C.
Lingyin Meng - One of the best experts on this subject based on the ideXlab platform.
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Bi-functional sulphonate-coupled reduced graphene oxide as an efficient dopant for a conducting polymer with enhanced Electrochemical Performance
Journal of Materials Chemistry C, 2020Co-Authors: Lingyin Meng, Frida Dagsgård, Anthony Turner, Cheung MakAbstract:The rapidly emerging field of organic bioelectronics has witnessed the wide use of conducting polymers (CPs) to fabricate advanced chemically modified electrodes (CMEs) for biosensors and biomedical devices. The Electrochemical Performance of the CPs in such devices is closely related to the quality and physiochemical nature of the dopants. A bi-functional graphene oxide derivative with high reduction degree and negatively-charged sulphonate functionality, i.e. sulphonate-coupled reduced graphene oxide (S-RGO), was developed and used as an efficient dopant for a CP with enhanced Electrochemical Performance. The S-RGO was synthesised via a facile one-pot hydrothermal reaction using 4-hydrazinobenzosulphonic acid (4-HBS) as reductant and sulphonate precursor simultaneously. The resulting S-RGO possesses high aqueous dispersion stability (more than 6 months), high electrical conductivity (1493.0 S m−1) and sulphonate functionality. Due to these specific properties, S-RGO demonstrated improved electropolymerisation efficiency for poly(3,4-ethylenedioxythiophene) (PEDOT) proving an effective dopant for the preparation of a PEDOT:S-RGO film (5 mC) with faster polymerisation time (37 s) compared to the conventional 2D dopants GO (PEDOT:GO, 129 s) and RGO (PEDOT:RGO, 66 s). The resulting PEDOT:S-RGO appeared as a homogenous film with uniformly distributed S-RGO dopant, low equivalent series resistance and low charge transfer resistance. Moreover, the Electrochemical transduction Performance of the PEDOT:S-RGO interface was evaluated with 4 different analytes, including ferric/ferrocyanide redox probe, dopamine, nicotinamide adenine dinucleotide and hydrogen peroxide. As a result of the synergistic effect of S-RGO and PEDOT, the PEDOT:S-RGO demonstrated enhanced Electrochemical Performance with respect to faster electrode kinetics (smaller ΔEp), ∼2 and ∼4 times increased current responses, and lower peak potentials compared to PEDOT:GO and PEDOT:RGO. This bi-functional S-RGO dopant combined the advantages of conventional GO and RGO to deliver sulphonate functionality and high conductivity for the preparation of advanced PEDOT interface with improved Electrochemical Performance, that could potentially be applied for applications in Electrochemical sensors, biosensors and bioelectronic devices.
Xiaodong Guo - One of the best experts on this subject based on the ideXlab platform.
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polyanion and cation co doping stabilized ni rich ni co al material as cathode with enhanced Electrochemical Performance for li ion battery
Nano Energy, 2019Co-Authors: Lang Qiu, Wei Xiang, Wen Tian, Tingru Chen, Kun Jia, Dong Wang, Xiaodong GuoAbstract:Abstract Layered Ni-rich transition metal oxides exert great potential as high-capacity cathode materials for lithium-ion batteries. However, structural degradation during lithiation/delithiation hinders the cathode materials for commercial utilization. Herein, PO43− polyanion and Mn4+ cation are co-doped into Ni-rich LiNi0.80Co0.15Al0.05O2 cathode to improve the structural stability and Electrochemical Performance. The effects of PO43− and Mn4+ co-existence on phase, crystal structure, element valence state, Electrochemical Performance and phase transition during lithiation/delithihation are systematically investigated. The results show that moderate content of PO43− and Mn4+ co-doping can enlarge the channel for Li+ lithiation/delithiation, lower the cationic mixing, and suppress the structural degradation during cycling. With the stabilization role of Mn4+ and PO43−, the material with moderate amount of dopants shows remarkable enhanced Electrochemical Performance, especially at harsh condition. In the cell potential of 2.7–4.3 V, the 3% PO43− and Mn4+ co-doped cathode shows a reversible discharge capacity of 204 mAh g−1 at 0.1C, outstanding cycling stability with a capacity of 174 mAh g−1 and capacity retention of 85.5% at 1C after 100 cycles, especially, a superior discharge capacity of 157.8 mAh g−1 at 5C. Even at elevated temperature of 55 °C, the cathode retains 80.9% of initial capacity (195 mAh g−1) at 1C after 100 cycles.
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a comparative study of crystalline and amorphous li0 5la0 5tio3 as surface coating layers to enhance the Electrochemical Performance of lini0 815co0 15al0 035o2 cathode
Journal of Alloys and Compounds, 2018Co-Authors: Wei Xiang, Xiaodong Guo, Weibo Hua, Xiaobing Zhang, Benhe ZhongAbstract:Abstract Surface coating is an effective strategy to boost the application of LiNi0.815Co0.15Al0.035O2 in the lithium ion batteries. The crystalline state of the coating layer is crucial for the transportation of lithium ions, the suppression of involved side reaction and the improvement of electrode structure stability, which ultimately determine the Electrochemical Performance. Here, the effects of crystalline state of Li0.5La0.5TiO3 on the Electrochemical Performance of LiNi0.815Co0.15Al0.035O2 are comparatively investigated. The Li0.5La0.5TiO3 coating layer with a thickness of about 2 nm is introduced on the surface of LiNi0.815Co0.15Al0.035O2, and the crystalline state (crystalline or amorphous) of coating layer is successfully controlled by tuning post-annealing temperature. The structure stability, dynamics Performance, reaction activity and Electrochemical Performance of the coated and pristine samples are investigated. Compared with the pristine sample, the coated materials both demonstrate superior Electrochemical Performance. And the crystalline Li0.5La0.5TiO3 coated sample shows a better capacity retention (94.5%) than the amorphous Li0.5La0.5TiO3 coated sample (88.0%). The improved Electrochemical Performance of crystalline Li0.5La0.5TiO3 coated sample could be ascribed to a better interface between the electrolyte and active material, which facilitates intercalation/extraction of lithium ions during the charge/discharge processes.