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Specific energy

About: Specific energy is a(n) research topic. Over the lifetime, 2282 publication(s) have been published within this topic receiving 50908 citation(s). The topic is also known as: energy density & massic energy.
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Journal ArticleDOI
Tianquan Lin1, I-Wei Chen2, Fengxin Liu1, Chongyin Yang1  +4 moreInstitutions (3)
18 Dec 2015-Science
TL;DR: It is found that a nitrogen-doped ordered mesoporous few-layer carbon has a capacitance of 855 farads per gram in aqueous electrolytes and can be bipolarly charged or discharged at a fast, carbon-like speed and can store a specific energy of 41 watt-hours per kilogram (19.5 watt- hours per liter).
Abstract: Carbon-based supercapacitors can provide high electrical power, but they do not have sufficient energy density to directly compete with batteries. We found that a nitrogen-doped ordered mesoporous few-layer carbon has a capacitance of 855 farads per gram in aqueous electrolytes and can be bipolarly charged or discharged at a fast, carbon-like speed. The improvement mostly stems from robust redox reactions at nitrogen-associated defects that transform inert graphene-like layered carbon into an electrochemically active substance without affecting its electric conductivity. These bipolar aqueous-electrolyte electrochemical cells offer power densities and lifetimes similar to those of carbon-based supercapacitors and can store a specific energy of 41 watt-hours per kilogram (19.5 watt-hours per liter).

1,425 citations


Journal ArticleDOI
Liangbing Hu1, Jang Wook Choi, Yuan Yang, Sangmoo Jeong  +3 moreInstitutions (1)
TL;DR: It is suggested that this conductive paper can be a highly scalable and low-cost solution for high-performance energy storage devices and as an excellent lightweight current collector in lithium-ion batteries to replace the existing metallic counterparts.
Abstract: Paper, invented more than 2,000 years ago and widely used today in our everyday lives, is explored in this study as a platform for energy-storage devices by integration with 1D nanomaterials. Here, we show that commercially available paper can be made highly conductive with a sheet resistance as low as 1 ohm per square (Ω/sq) by using simple solution processes to achieve conformal coating of single-walled carbon nanotube (CNT) and silver nanowire films. Compared with plastics, paper substrates can dramatically improve film adhesion, greatly simplify the coating process, and significantly lower the cost. Supercapacitors based on CNT-conductive paper show excellent performance. When only CNT mass is considered, a specific capacitance of 200 F/g, a specific energy of 30–47 Watt-hour/kilogram (Wh/kg), a specific power of 200,000 W/kg, and a stable cycling life over 40,000 cycles are achieved. These values are much better than those of devices on other flat substrates, such as plastics. Even in a case in which the weight of all of the dead components is considered, a specific energy of 7.5 Wh/kg is achieved. In addition, this conductive paper can be used as an excellent lightweight current collector in lithium-ion batteries to replace the existing metallic counterparts. This work suggests that our conductive paper can be a highly scalable and low-cost solution for high-performance energy storage devices.

1,101 citations


Journal ArticleDOI
Zhaohui Chen, J. R. Dahn1Institutions (1)
Abstract: Efforts were made to synthesize LiFePO 4 /C composites showing good rale capability and high energy density while attempting to minimize the amount of carbon in the composite. First, three carbon-coated samples, one coated with carbon after the synthesis of pure LiFePO 4 , one synthesized with sugar added before the heating steps, and one synthesized with sugar added before heating and subsequently coated with carbon, were studied. The resulting carbon contents for these samples arc 2.7, 3.5, and 6.2 wt %, respectively. Electrochemical tests showed that the latter two samples had comparable rate capabilities to the LiFePO 4 /C composite (15 wt % carbon) recently reported by Huang et al. We believe the synthesis of LiFePO 4 with sugar added before heating is the best method because it gives particles having uniform small size that are covered by carbon. Further studies of samples made by this method show that a very small percentage of carbon, even less than 1 wt %, causes a significant increase in rate capability, hut unfortunately, a dramatic decrease in tap density. To make LiFePO 4 /C composites having good rate capability, high energy density, and high tap density, the carbon content and method for coating carbon onto the LiFePO 4 particles must he given careful attention. However, based on the studies reported here, we are not certain that all desired parameters can he simultaneously achieved, and this may limit the usefulness of LiFePO 4 in some practical applications.

749 citations


Journal ArticleDOI
Abstract: The fundamental problem in rock working is the breakage of fragments out of the face of a solid wall of rock. Mechanically this can be done only by forcing a tool into the rock surface, after the manner of an ‘indenter’ such as is commonly used for testing surface hardness. Since the process breaks rather than cuts solid rock into small fragments of assorted sizes it can be regarded as essentially one of crushing. As in crushing processes generally, energy/volume relationships are therefore of interest. ‘Specific energy’, defined as the energy required to excavate unit volume of rock, is a useful parameter in this context and may also be taken as an index of the mechanical efficiency of a rock-working process. In drilling data from a number of sources its minimum value appears to be very roughly correlated with the crushing strength of the medium drilled in, for rotary, percussive-rotary and roller-bit drilling. The implications of this are discussed.

622 citations


Journal ArticleDOI
Kuo-Chuan Liu1, Marc A. Anderson1Institutions (1)
Abstract: Nano-sized NiO/Ni composite films have been found to perform as superior electrodes in electrochemical capacitor applications. These films can provide a specific capacitance of 50 to 64 F/g. The specific energy and specific power of these films were 25 to 40 kJ/kg and 4 to 17 kW/kg, respectively. These specific quantities are dependent on the microstructure of the films. Superior performance can be obtained from samples having rough surfaces and consisting of larger secondary particles (ca. 100 to 120 nm in diam).

507 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20228
2021220
2020181
2019140
2018172
2017150

Top Attributes

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Topic's top 5 most impactful authors

Muhammad Zahir Iqbal

11 papers, 75 citations

Michael P Sealy

7 papers, 162 citations

Meshal Alzaid

6 papers, 34 citations

Parviz Pourghahramani

5 papers, 202 citations

C. Igathinathane

4 papers, 241 citations