排序方式: 共有42条查询结果,搜索用时 31 毫秒
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Conducting polymers (CPs) are attractive pseudocapacitive materials which show the highest capacitance under positive potentials in aqueous protic electrolytes. One way to expand their voltage window (thus energy density) in aqueous electrolytes is to manufacture asymmetric supercapacitors using distinctly different anodes. However, CPs lack matching pseudocapacitive anode materials that can perform well in protic electrolytes (e.g., sulfuric acid). 2D titanium carbide (Ti3C2Tx), MXene, as a universal pseudocapacitive anode material for a range of CPs, such as polyaniline, polypyrrole, and poly(3,4‐ethylenedioxythiophene) deposited on reduced graphene oxide (rGO) sheets, is reported here. All‐pseudocapacitive organic–inorganic asymmetric devices with MXene cathodes and rGO–polymer anodes can operate in voltage windows up to 1.45 V in 3 m H2SO4. Most importantly, these devices show outstanding cycling performance, outperforming many reported asymmetric pseudocapacitors. 相似文献
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Qiu Jiang Narendra Kurra Kathleen Maleski Yongjiu Lei Hanfeng Liang Yizhou Zhang Yury Gogotsi Husam N. Alshareef 《Liver Transplantation》2019,9(26)
Microsupercapacitors (MSCs) with high energy densities offer viable miniaturized alternatives to bulky electrolytic capacitors if the former can respond at the kilo Hertz (kHz) or higher frequencies. Moreover, MSCs fabricated on a chip can be integrated into thin‐film electronics in a compatible manner, serving the function of ripple filtering units or harvesters of energy from high‐frequency sources. In this work, wafer‐scale fabrication is demonstrated of MXene microsupercapacitors with controlled flake sizes and engineered device designs to achieve excellent frequency filtering performance. Specifically, the devices (100 nm thick electrodes and 10 µm interspace) deliver high volumetric capacitance (30 F cm?3 at 120 Hz), high rate capability (300 V s?1), and a very short relaxation time constant (τ0 = 0.45 ms), surpassing conventional electrolytic capacitors (τ0 = 0.8 ms). As a result, the devices are capable of filtering 120 Hz ripples produced by AC line power at a frequency of 60 Hz. This study opens new avenues for exploring miniaturized MXene MSCs as replacements for bulky electrolytic capacitors. 相似文献
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Lianghao Yu Zhaodi Fan Yuanlong Shao Zhengnan Tian Jingyu Sun Zhongfan Liu 《Liver Transplantation》2019,9(34)
Printing is regarded as a revolutionary and feasible technique to guide the fabrication of versatile functional systems with designed architectures. 2D MXenes are nowadays attractive in printed energy storage devices. However, owing to the van der Waals interaction between the MXene layers, the restacking issues within the printed electrodes can significantly impede the ion/electrolyte transport and hence handicap the electrochemical performances. Herein, a melamine formaldehyde templating method is demonstrated to develop crumpled nitrogen‐doped MXene (MXene‐N) nanosheets. The nitrogen doping boosts the electrochemical performances of MXene via enhanced conductivity and redox activity. Accordingly, two types of MXene‐N inks are prepared throughout the optimization of the ink viscosity to fit the 2D screen printing and 3D extrusion printing, respectively. As a result, the screen printed MXene‐N microsupercapacitor delivers an areal capacitance of 70.1 mF cm?2 and outstanding mechanical robustness. Furthermore, the 3D‐printed MXene‐N based supercapacitor manifests an areal capacitance of 8.2 F cm?2 for a three‐layered electrode and readily stores a high areal energy density of 0.42 mWh cm?2. The approach to harnessing such versatile MXene‐N inks offers distinctive insights into the printed energy storage systems with high areal energy density and large scalability. 相似文献
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Xiaobin Hui Ruizheng Zhao Peng Zhang Caixia Li Chengxiang Wang Longwei Yin 《Liver Transplantation》2019,9(33)
Silicon is attracting enormous attention due to its theoretical capacity of 4200 mAh g?1 as an anode for Li‐ion batteries (LIBs). It is of fundamental importance and challenge to develop low‐temperature reaction route to controllably synthesize Si/Ti3C2 MXene LIBs anodes. Herein, a novel and efficient strategy integrating in situ orthosilicate hydrolysis and a low‐temperature reduction process to synthesize Si/Ti3C2 MXene composites is reported. The hydrolysis of tetraethyl orthosilicate leads to homogenous nucleation and growth of SiO2 nanoparticles on the surface of Ti3C2 MXene. Subsequently, SiO2 nanoparticles are reduced to Si via a low‐temperature (200 °C) reduction route. Importantly, Ti3C2 MXene not only provides fast transfer channels for Li+ and electrons, but also relieves volume expansion of Si during cycling. Moreover, the characteristics of excellent pseudocapacitive performance and high conductivity of Ti3C2 MXene can synergistically contribute to the enhancement of energy storage performance. As expected, Ti3C2/Si anode exhibits an outstanding specific capacity of 1849 mAh g?1 at 100 mA g?1, even retaining 956 mAh g?1 at 1 A g?1. The low‐temperature synthetic route to Si/Ti3C2 MXene electrodes and involved battery‐capacitive dual‐model energy storage mechanism has potential in the design of novel high‐performance electrodes for energy storage devices. 相似文献
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Solving the Capacitive Paradox of 2D MXene using Electrochemical Quartz‐Crystal Admittance and In Situ Electronic Conductance Measurements
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Mikhael D. Levi Maria R. Lukatskaya Sergey Sigalov Majid Beidaghi Netanel Shpigel Leonid Daikhin Doron Aurbach Michel W. Barsoum Yury Gogotsi 《Liver Transplantation》2015,5(1)
Fast ion adsorption processes in supercapacitors enable quick storage/delivery of significant amounts of energy, while ion intercalation in battery materials leads to even larger amounts of energy stored, but at substantially lower rates due to diffusional limitations. Intercalation of ions into the recently discovered 2D Ti3C2Tx (MXene) occurs with a very high rate and leads to high capacitance, posing a paradox. Herein, by characterizing the mechanical deformations of MXene electrode materials at various states‐of‐charge with a variety of cations (Li, Na, K, Cs, Mg, Ca, Ba, and three tetraalkylammonium cations) during cycling by electrochemical quartz‐crystal admittance (EQCA, quartz‐crystal microbalance with dissipation monitoring) combined with in situ electronic conductance and electrochemical impedance, light is shone on this paradox. Based on this work, it appears that the capacitive paradox stems from cationic insertion, accompanied by significant deformation of the MXene particles, that occurs so rapidly so as to resemble 2D ion adsorption at solid‐liquid interfaces. The latter is greatly facilitated by the presence of water molecules between the MXene sheets. 相似文献
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Yongzheng Shi Bin Li Qi Zhu Kai Shen Wenjing Tang Qian Xiang Weihua Chen Chuntai Liu Jiayan Luo Shubin Yang 《Liver Transplantation》2020,10(9)
Although solid polymer electrolytes have some intrinsic advantages in synthesis and film processing compared with inorganic solid electrolytes, low ionic conductivities and mechanical moduli hamper their practical applications in lithium‐based batteries. Here, an efficient strategy is developed to produce a unique solid polymer electrolyte containing MXene‐based mesoporous silica nanosheets with a sandwich structure, which are fabricated via controllable hydrolysis of tetraethyl orthosilicate around the surface of MXene‐Ti3C2 under the direction of cationic surfactants. Such unique nanosheets not only exhibit individual, thin, and insulated features, but also possess abundant functional groups in mesopores and on the surface, which are favorable for the formation of Lewis acid–base interactions with anions in polymer electrolytes such as poly(propylene oxide) elastomer, enabling the fast Li+ transportation at the mesoporous nanosheets/polymer interfaces. As a consequence, a solid polymer electrolyte with high ionic conductivity of 4.6 × 10?4 S cm?1, high Young's modulus of 10.5 MPa, and long‐term electrochemical stability is achieved. 相似文献
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Self‐Assemble and In Situ Formation of Ni1−xFexPS3 Nanomosaic‐Decorated MXene Hybrids for Overall Water Splitting
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Cheng‐Feng Du Khang Ngoc Dinh Qinghua Liang Yun Zheng Yubo Luo Jianli Zhang Qingyu Yan 《Liver Transplantation》2018,8(26)
Herein, the authors present the development of novel 0D–2D nanohybrids consisting of a nickel‐based bimetal phosphorus trisulfide (Ni1?xFexPS3) nanomosaic that decorates on the surface of MXene nanosheets (denoted as NFPS@MXene). The nanohybrids are obtained through a facile self‐assemble process of transition metal layered double hydroxide (TMLDH) on MXene surface; followed by a low temperature in situ solid‐state reaction step. By tuning the Ni:Fe ratio, the as‐synthesized NFPS@MXene nanohybrids exhibit excellent activities when tested as electrocatalysts for overall water splitting. Particularly, with the initial Ni:Fe ratio of 7:3, the obtained Ni0.7Fe0.3PS3@MXene nanohybrid reveals low overpotential (282 mV) and Tafel slope (36.5 mV dec?1) for oxygen evolution reaction (OER) in 1 m KOH solution. Meanwhile, the Ni0.9Fe0.1PS3@MXene shows low overpotential (196 mV) for the hydrogen evolution reaction (HER) in 1 m KOH solution. When integrated for overall water splitting, the Ni0.7Fe0.3PS3@MXene || Ni0.9Fe0.1PS3@MXene couple shows a low onset potential of 1.42 V and needs only 1.65 V to reach a current density of 10 mA cm?2, which is better than the all noble metal IrO2 || Pt/C electrocatalyst (1.71 mV@10 mA cm?2). Given the chemical versatility of Ni1?xFexPS3 and the convenient self‐assemble process, the nanohybrids demonstrated in this work are promising for energy conversion applications. 相似文献
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Achieving High Pseudocapacitance of 2D Titanium Carbide (MXene) by Cation Intercalation and Surface Modification
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Jian Li Xiaotao Yuan Cong Lin Yanquan Yang Le Xu Xin Du Jinglin Xie Jianhua Lin Junliang Sun 《Liver Transplantation》2017,7(15)
Supercapacitors attract great interest because of the increasing and urgent demand for environment‐friendly high‐power energy sources. Ti3C2, a member of MXene family, is a promising electrode material for supercapacitors owing to its excellent chemical and physical properties. However, the highest gravimetric capacitance of the MXene‐based electrodes is still relatively low (245 F g?1) and the key challenge to improve this is to exploit more pseudocapacitance by increasing the active site concentration. Here, a method to significantly improve the gravimetric capacitance of Ti3C2Tx MXenes by cation intercalation and surface modification is reported. After K+ intercalation and terminal groups (OH?/F?) removing , the intercalation pseudocapacitance is three times higher than the pristine MXene, and MXene sheets exhibit a significant enhancement (about 211% of the origin) in the gravimetric capacitance (517 F g?1 at a discharge rate of 1 A g?1). Moreover, the as‐prepared electrodes show above 99% retention over 10 000 cycles. This improved electrochemical performance is attributed to the large interlayer voids of Ti3C2 and lowest terminated surface group concentration. This study demonstrates a new strategy applicable to other MXenes (Ti2CTx , Nb2CTx , etc.) in maximizing their potential applications in energy storage. 相似文献