A Lithographically Patterned Capacitor with Horizontal Nanowires of Length 2.5 mm

Yan, Wenbo; Thai, Mya Le; Dutta, Rajen K.; Li, Xiaowei; Xing, Weiyi; Penner, Reginald M.

doi:10.1021/am500051d

Cited by 18 publications

(44 citation statements)

References 28 publications

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“…In contrast, in our previous work this was not the case: We have either measured C sp without removing the gold edge in the LPNE process, 12 enforcing intimate contact between the gold current collector and the nanowire edge along its entire length, or we have prepared and studied core/shell nanowires 11,39 in which a gold nanowire core is surrounded by a MnO 2 shell where, again, proximity (within 100 nm) between the current collector and MnO 2 is enforced by the geometry. The difference between 100 nm maximum electrical path length through MnO 2 (in prior work) and 5 μm (in this work) is significant.…”

Section: Chemistry Of Materialsmentioning

confidence: 94%

In Situ Electrical Conductivity of Li_xMnO₂ Nanowires as a Function of x and Size

Le¹,

Liu²,

Wang

et al. 2015

Chem. Mater.

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Manganese oxide, MnO 2 , excels as a hybrid electrical energy storage material: The manganese centers in MnO 2 are capable of undergoing a reduction from 4+ to 3+ balanced by the intercalation of lithium ions to form Li x MnO 2 while its conductive surfaces simultaneously store energy as an electrical double layer capacitor. The highest capacitance and power performance for MnO 2 has been obtained for ensembles of nanowires that are 200 nm or less in width and many microns in length. Typically such MnO 2 nanowires are attached to a current collector at just one end, and electrical conductivity of the nanowire is therefore required in order to maintain a consistent redox and charge state along its axis. The electrical conductance of the nanowire therefore plays a very important role, and yet this parameter has been measured in few previous studies. In this work, we directly measure the electrical conductance of δ-MnO 2 nanowires in situ in 1 M LiClO 4 , acetonitrile as a function of the equilibrium Li content for nanowires with varying lateral dimensions. This measurement is accomplished using arrays of 200 MnO 2 nanowires that are 40−60 nm in height and 275−870 nm in width and which span a 10 μm gap between two gold contacts. Nanowires of fully oxidized MnO 2 are first prepared at +0.60 V vs MSE in acetonitrile. As the equilibrium electrode potential is decreased from 0.60 V to −0.80 V and lithium is intercalated, the electrical conductivity of MnO 2 nanowires increases by up to 1 order of magnitude. The measured change in conductivity is dependent on the equilibrium potential, which in turn is related to the Li content, and also depends on the width of nanowires. After doping at −0.80 V vs MSE, the conductivity increases by 30% for a 870 nm wide nanowire array and 880% for a 275 nm wide nanowire array. TEM investigations implicate the nanowire porosity in this difference.

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Section: Chemistry Of Materialsmentioning

confidence: 94%

In Situ Electrical Conductivity of Li_xMnO₂ Nanowires as a Function of x and Size

Le¹,

Liu²,

Wang

et al. 2015

Chem. Mater.

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“…[6][7][8][9][10][11][12][13] In our prior work with symmetrical Au@δ-MnO 2 nanowire arrays, involving both gel and liquid electrolytes, V max = 1.2 V has been used. 1,2 We report here that that the PMMA gel electrolyte enables the use of a V max of 1.8 V while retaining both C sp and cycle stability to 100,000. In theory, this 50% increase in V max relative to 1.2 V translates into an energy enhancement of 2.25 times, based upon E = (1/2)CV 2 max .…”

mentioning

confidence: 87%

“…For symmetrical Au@δ-MnO 2 nanowire capacitors operating in 1.0 M LiClO 4 in propylene carbonate (PC) or acetonitrile, a reversible capacity of 4000-8000 cycles is reproducibly observed. 1,2 Recently, we reported 2 that adding 20 w/w% poly(methylmethacrylate)(PMMA) to the liquid electrolyte (1.0 M LiClO 4 in propylene carbonate) extends the cycle lifetime to 100,000 cycles or more. In that study, we exploited a symmetrical, all-nanowire capacitor consisting of two interpenetrating arrays of 375 ultra-long (5 mm) core@shell, Au@δ-MnO 2 nanowires 1 lithographically patterned at 20 µm pitch onto a glass surface using the LPNE process.…”

mentioning

confidence: 99%

Collateral Advantages of a Gel Electrolyte for MnO₂ Nanowire Capacitors: Higher Voltage and Reduced Volume

et al. 2017

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Recently we demonstrated that symmetric, all Au@ δ-MnO 2 core@shell nanowire capacitors can achieve cycle stability to 100 000 cycles and beyond in a poly(methyl methacrylate) (PMMA) gel electrolyte. Here we examine the limits of the PMMA gel to confer this extraordinary stability, in terms of the accessible maximum voltage, V max , and the thickness of the PMMA gel electrolyte layer. Two conclusions are (1) the PMMA gel permits the V max to be increased by 50% from 1.2 V to 1.8 V, allowing the specific energy to be increased 5−6 fold, and (2) the PMMA gel layer thickness can be reduced from 180 μm (previously) to 2 μm while simultaneously utilizing two layers of nanowires and patterning nanowires in each layer at 5× higher density. For this nanowire "sandwich" architecture, a net increase in volumetric capacity of 600× up to 500 mF/cm 3 can be achieved while retaining cycle stability to 100 000 cycles.

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“…Recently, however, a study by Le Thai et al demonstrated a model electrochemical cell design using ultra-long δ-MnO 2 mesowires exhibiting cycling stability up to 200k cycles, 5,9 several times better than anything reported previously in the literature. A key innovation in the previous study was the inclusion of a gel-based electrolyte, composed of LiClO 4 / propylene carbonate (PC) solution and poly(methyl) methacrylate (PMMA).…”

Section: Introductionmentioning

confidence: 95%

Ion transport in gel and gel–liquid systems for LiClO₄-doped PMMA at the meso- and nanoscales

et al. 2017

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Solid and gel electrolytes offer significant advantages for cycle stability and longevity in energy storage technologies. These advantages come with trade-offs such as reduced conductivity and ion mobility, which can impact power density in storage devices even at the nanoscale. Here we propose experiments aimed at exploring the ion transport properties of a hybrid electrolyte system of liquid and gel electrolytes with meso and nanoscale components. We focus on single pore systems featuring LiClO-propylene carbonate and LiClO-PMMA gel, which are model electrolytes for energy storage devices. We identified conditions at which the systems considered featured rectifying current-voltage curves, indicating a preferential direction of ion transport. The presented ion current rectification suggests different mechanisms arising from the unique hybrid system: (i) PMMA structure imposing selectivity in fully immersed systems and (ii) ionic selectivity linked to ion sourcing from media of different ionic mobility. These mechanisms were observed to interplay with ion transport properties linked to nanopore structure i.e. cylindrical and conical.

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A Lithographically Patterned Capacitor with Horizontal Nanowires of Length 2.5 mm

Cited by 18 publications

References 28 publications

In Situ Electrical Conductivity of Li_xMnO₂ Nanowires as a Function of x and Size

In Situ Electrical Conductivity of Li_xMnO₂ Nanowires as a Function of x and Size

Collateral Advantages of a Gel Electrolyte for MnO₂ Nanowire Capacitors: Higher Voltage and Reduced Volume

Ion transport in gel and gel–liquid systems for LiClO₄-doped PMMA at the meso- and nanoscales

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A Lithographically Patterned Capacitor with Horizontal Nanowires of Length 2.5 mm

Cited by 18 publications

References 28 publications

In Situ Electrical Conductivity of LixMnO2 Nanowires as a Function of x and Size

In Situ Electrical Conductivity of LixMnO2 Nanowires as a Function of x and Size

Collateral Advantages of a Gel Electrolyte for MnO2 Nanowire Capacitors: Higher Voltage and Reduced Volume

Ion transport in gel and gel–liquid systems for LiClO4-doped PMMA at the meso- and nanoscales

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In Situ Electrical Conductivity of Li_xMnO₂ Nanowires as a Function of x and Size

In Situ Electrical Conductivity of Li_xMnO₂ Nanowires as a Function of x and Size

Collateral Advantages of a Gel Electrolyte for MnO₂ Nanowire Capacitors: Higher Voltage and Reduced Volume

Ion transport in gel and gel–liquid systems for LiClO₄-doped PMMA at the meso- and nanoscales