This study shows how the simple modulation of the cathode/anode mass ratio, in a Li-ion capacitor based on activated carbon (AC) and Li4Ti5O12 (LTO), results in a drastic increase in performance. ...Starting with a device balanced in the classical way (with an AC/LTO mass ratio of 4.17), the cathode/anode mass ratio has been reduced to 1.54 and then to 0.72. At a high power density, the device with a cathode/anode mass ratio of 0.72 shows the highest energy density. In fact, at 2.3 kW L−1, it delivers an energy density of 31 Wh L−1, which is almost 10 times greater than the energy obtained with a capacitor balanced with an AC/LTO ratio of 4.17 (3.68 Wh L−1). Moreover, the reduction in the cathode/anode mass ratio from 4.17 to 0.72 improves the cycling stability with a factor of 4.8 after 1000 cycles at 10C. Electrochemical impedance spectroscopy reveals that the better power performance is due to reduced diffusion and charge transfer resistances. In addition, the anode polarization is less pronounced for the system with a lower AC/LTO mass ratio, leading to a minimization in electrolyte decomposition on the anode surface and therefore limiting the increase in the electrode resistance during cycles.
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•The performance of an AC//LTO asymmetric supercapacitor has been improved by modulating the electrode masses.•An AC/LTO mass ratio of 0.72 leads to higher energy density at high power density.•Lower AC/LTO mass ratio gives lower diffusion and charge transfer resistances.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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•1M LiPF6 in PC displays the widest electrochemical stability window among others couples electrolyte/activated carbon.•Electrolytes based on EC-DMC show lower impedance than ...electrolytes containing PC.•1M LiPF6 in PC has the highest cycling stability with 75% of capacitance retention after 20 000 cycles.
The fast development of Li-ion capacitor (LIC) technologies requires the use of low resistance and stable electrolytes. An electrolyte for a LIC not only has to provide Li for the intercalation/deintercalation of the battery-type materials, but it also needs to be compatible with the supercapacitor material. Before designing a hybrid Li-ion capacitor device containing Li-insertion and double layer-type materials, it is necessary to understand and separate the contribution of each electrode material to the resistance, capacity and stability in the chosen electrolyte. Due to the intensive research on Li-ion batteries, the interactions of Li-salt containing electrolytes combined with Li insertion materials have been extensively investigated, and a lot of literature is available on this field. In contrast, there is only little knowledge about the exclusive interaction and compatibility of Li containing electrolytes with supercapacitor-type electrode materials (in absence of battery materials). With this purpose, this paper explores the electrochemical performance of electrodes based on commercial activated carbon (AC) in various lithium salt-containing electrolytes. A standard electrolyte for Li-ion batteries (1M LiPF6 in EC:DMC, 1:1) is evaluated and compared with an electrolyte prepared with the same salt dissolved in propylene carbonate (1M LiPF6 in PC) which is a solvent typically used in commercial supercapacitors. Furthermore, two new electrolyte solutions are proposed, based on a blend of salts 0.8M LiPF6+0.2M NEt4BF4 in EC:DMC (1:1) as well as in pure PC. The effect of the electrolyte composition is evaluated in half and full cells. Resistances, rate capabilities, the electrochemical stability window (ESW) and cycling abilities of activated carbon electrodes are compared in different electrolytes using electrochemical impedance spectroscopy (EIS), cyclic voltammetry and galvanostatic cycling techniques. Among all electrolytes, 1M LiPF6 in PC displays the best performance with the widest ESW and an excellent cycling stability, retaining 75% of its initial capacitance after 20 000 cycles. However, due to its high viscosity, PC-based electrolytes show higher resistances in comparison to EC/DMC-based electrolytes. These results are the basis for further investigation on organic Li-salt containing electrolytes for the development of hybrid supercapacitor technology in which activated carbon and Li-insertion materials are combined together.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Traumatische Erfahrungen von Kindern und Jugendlichen werden in diesem Handbuch in den Kontext schulischer Bildung und Erziehung gestellt. Die inter- und transdisziplinären Beiträge arbeiten ...traumaspezifisches und differenzsensibles Wissen auf, zeigen wie Vulnerabilität fernab vorherrschender Diagnosen gedacht werden kann und welche Unterstützungsleistungen Kinder und Jugendliche mit traumatischen Erlebnissen im schulischen Alltag erfahren können.Das Handbuch bietet Orientierung innerhalb der wissenschaftlichen Perspektiven zum Phänomen und zur Politik des Traumas und lädt ein, die Differenzen und Ambivalenzen von Leid in Bildungsprozessen anders zu denken.
Nanostructured Li
3
V
2−
x
Ni
x
(PO
4
)
3
(
x
= 0, 0.05, and 0.1) cathode materials, with a mean particle dimension ranging from 200 to 63 nm, are successfully synthesized with poly(acrylic acid) and
...d
-(+)-glucose as carbon sources. All three samples show a monoclinic crystalline structure as confirmed by X-ray diffraction and Rietveld analysis. Ni-doping improves the specific capacity of Li
3
V
2
(PO
4
)
3
/C. Between 3.0 and 4.3 V
vs.
Li
+
/Li, all cathodes exhibit good rate capability, even at high C-rates. For these reasons, they are good candidates for high power and energy applications, in particular for the development of high energy density supercapacitors. Li
3
V
1.95
Ni
0.05
(PO
4
)
3
/C, because of its highest specific discharge capacity (93 mA h g
−1
at 100 C) and capacity retention of 97% after 1000 cycles, is selected for building an asymmetric supercapacitor with activated carbon as the anode. At a power density of 2.8 kW L
−1
, the asymmetric system delivers 18.7 W h L
−1
, a value five orders of magnitude higher than that of the symmetric capacitor at the same power level.
Nanostructured Li
3
V
2−
x
Ni
x
(PO
4
)
3
(
x
= 0, 0.05, and 0.1) cathodes, thanks to their high rate capability and excellent cycle stability, are proposed as excellent candidates for the development of high energy and high power density Li-ion asymmetric supercapacitors.
Nanostructured Li sub(3)V sub(2-x)Ni sub(x)(PO sub(4)) sub(3) (x= 0, 0.05, and 0.1) cathode materials, with a mean particle dimension ranging from 200 to 63 nm, are successfully synthesized with ...poly(acrylic acid) and d-(+)-glucose as carbon sources. All three samples show a monoclinic crystalline structure as confirmed by X-ray diffraction and Rietveld analysis. Ni-doping improves the specific capacity of Li sub(3)V sub(2)(PO sub(4)) sub(3)/C. Between 3.0 and 4.3 V vs. Li super(+)/Li, all cathodes exhibit good rate capability, even at high C-rates. For these reasons, they are good candidates for high power and energy applications, in particular for the development of high energy density supercapacitors. Li sub(3)V sub(1.95)Ni sub(0.05)(PO sub(4)) sub(3)/C, because of its highest specific discharge capacity (93 mA h g super(-1) at 100 C) and capacity retention of 97% after 1000 cycles, is selected for building an asymmetric supercapacitor with activated carbon as the anode. At a power density of 2.8 kW L super(-1), the asymmetric system delivers 18.7 W h L super(-1), a value five orders of magnitude higher than that of the symmetric capacitor at the same power level.
Nanostructured Li 3 V 2−x Ni x (PO 4 ) 3 ( x = 0, 0.05, and 0.1) cathode materials, with a mean particle dimension ranging from 200 to 63 nm, are successfully synthesized with poly(acrylic acid) and ...d -(+)-glucose as carbon sources. All three samples show a monoclinic crystalline structure as confirmed by X-ray diffraction and Rietveld analysis. Ni-doping improves the specific capacity of Li 3 V 2 (PO 4 ) 3 /C. Between 3.0 and 4.3 V vs. Li + /Li, all cathodes exhibit good rate capability, even at high C-rates. For these reasons, they are good candidates for high power and energy applications, in particular for the development of high energy density supercapacitors. Li 3 V 1.95 Ni 0.05 (PO 4 ) 3 /C, because of its highest specific discharge capacity (93 mA h g −1 at 100 C) and capacity retention of 97% after 1000 cycles, is selected for building an asymmetric supercapacitor with activated carbon as the anode. At a power density of 2.8 kW L −1 , the asymmetric system delivers 18.7 W h L −1 , a value five orders of magnitude higher than that of the symmetric capacitor at the same power level.
The angiotensin II antagonistic effects of candesartan and losartan were compared in‐vivo after single and repeated doses. Effects were related to antagonistic activity in plasma.
In this ...double‐blind, crossover study, 12 healthy male volunteers received, in random order, daily oral doses of 8 mg candesartan cilexetil or 50 mg losartan for seven days. On day 1 and day 8, dynamics and kinetics were assessed up to 48 h after dosing. Antagonistic effect was determined from the antagonist‐induced rightward shifts of the diastolic blood pressure response curves to exogenously administered angiotensin II measured as the dose ratio (DR). The antagonistic activity in plasma was measured using an ex‐vivo/in‐vitro radioreceptor assay. Specific high‐performance liquid chromatography assays determined plasma concentrations of candesartan, losartan and its active metabolite EXP‐3174.
The pharmacokinetic properties of candesartan and losartan were comparable and antagonistic activity in plasma almost identical (ratio candesartan: losartan = 0.97 and 1.2 after single and multiple doses, respectively). However, the antagonistic effects of candesartan and losartan in‐vivo were quite different. Twenty‐four hours after single dosing with candesartan a clinically relevant rightward shift in the angiotensin II dose‐response curve (DR = 3.2) occurred that was more pronounced than that following losartan administration (DR = 2.1, ratio candesartan: losartan = 1.65). Twenty‐four hours after multiple doses of candesartan or losartan, the values of the DR were 4.8 and 2.3, respectively (ratio candesartan: losartan = 1.94). The values of DR for candesartan were significantly higher compared with losartan between 6 and 36 h after a single dose and between 3 and 24 h post‐dose following multiple dose administration. A counter‐clockwise hysteresis was apparent between antagonistic activity in plasma and antagonistic effect.
Despite equivalent angiotensin II antagonistic activity in plasma, the pharmacodynamic effect of candesartan cilexetil was greater than that of losartan. Candesartan appeared to have a slower off‐rate from the angiotensin AT1‐receptor compared with losartan, nevertheless differences in distributional phenomena or the extent of insurmountable antagonistic activity cannot be ruled out.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
