NOVELTY - Forming electrode involves providing first fluid containing carbon-based nanostructures (14) comprising positively-charged groups; providing second fluid containing carbon-based nanostructures (18) comprising negatively-charged groups; exposing first portion of surface of substrate (10) to first fluid and depositing, proximate to first surface portion, a first set of carbon-based nanostructures; and separately exposing second portion of surface of substrate to second fluid and depositing, proximate to second substrate surface portion, a second set of carbon-based nanostructures.    USE - For forming an electrode useful in a device e.g. energy storage device selected from capacitor, fuel cell, photovoltaic cell and electrochemical cell (claimed); useful in transistors, photovoltaic devices, electrodes, semiconductors, high strength polymer materials, transparent conductors, barrier materials, energy production devices.    ADVANTAGE - The carbon-based nanostructure assembly exhibits enhanced properties such as improved arrangement of carbon-based nanostructures (e.g. carbon nanotubes) and/or enhanced electronic and/or ionic conductivity. The device achieves high capacitance (per unit volume and/or mass), high energy density, and/or high specific energy. The carbon-based nanostructure achieves a capacitance at the electrode of at least 300 (preferably at least 400, especially at least 450) Farads per cubic centimeter of the electrode, a capacitance at the electrode of at least 400 Farads per gram of the electrode, an energy density at the electrode of at least 400 (preferably at least 600, especially at least 700, particularly at least 750) Watt-hours per liter of the electrode, and a specific energy at the electrode of at least 500 (preferably at least 600, especially at least 800, particularly at least 900) Watt-hours per kilogram of the electrode. The electrode or composition is free of binder. After alternatively charging and discharging the device for 10, 100 or 1000 times, the device exhibits a capacitance or energy density of at least 50% of the device's initial capacitance or energy density at the end of the tenth, 100th or 1000th cycle. The electrode or composition transmits at least 15% (preferably at least 20%, especially at least 30%) of incident visible light within the range of 500 to 600 run. The device provides power at the electrode at a rate of at least 1 kW per kilogram of the electrode. The method for processing carbon-based nanostructure allows facile deposition, relative to previous methods, of thin films. The method (M1) reduces the level of precipitation or agglomeration of carbon-based nanostructures in solution, compared to previous methods. The assembly of carbon-based nanostructures is free of binder and/or other non-carbon materials, resulting in high packing density of the carbon-based nanostructures. Assemblies of carbon-based nanostructures exhibit the transmittance properties as a function of thickness and/or number of bilayers in coordination with any of the performance metrics (e.g. capacitance, energy density, specific energy metrics, supplied power, charge rates, discharge rates, low energy losses, retention of properties over multiple charge/discharge cycles) and/or material properties (e.g. low void volumes between carbon-based nanostructures, free of binder). The device exhibits fast charge and discharge rates; and provides high power outputs. The amount of energy lost (e.g. as lost heat) during charge and/or discharge of a device comprising an electrode comprising carbon-based nanostructures is relatively low.    DETAILED DESCRIPTION - Method (M1) of forming an electrode involves providing a first fluid containing carbon-based nanostructures (14) comprising positively-charged functional groups; providing a second fluid containing carbon-based nanostructures (18) comprising negatively-charged functional groups; exposing a first portion of a surface of a substrate (10) to the first fluid and depositing, proximate to the first substrate surface portion, a first set of carbon-based nanostructures; and separately exposing a second portion of a surface of the substrate, which can be the same or different from the first substrate surface portion, to the second fluid and depositing, proximate to the second substrate surface portion, a second set of carbon-based nanostructures. INDEPENDENT CLAIMS are included for the following:    (1) an electrode with thickness of at least 10 nm comprising carbon-based nanostructures having composition volume, where each of the carbon-based nanostructures has a nanostructure volume, and the total volumes of the nanostructures has at least 60% of the composition volume;    (2) a device (D1) comprising an electrode having carbon-based nanostructures capable of achieving a capacitance at the electrode of at least 300 Farads per cubic centimeter of the electrode, a capacitance at the electrode of at least 400 Farads per gram of the electrode, an energy density at the electrode of at least 400 Watt-hours per liter of the electrode, or a specific energy at the electrode of at least 500 Watt-hours per kilogram of the electrode;    (3) a device (D2) comprising an electrode capable of converting at least 60% of energy input into the device during a charging step to energy stored within the device, where the charging step performed so as to charge the device to a capacity of at least 50% within 1 second, and the charging step is performed at a rate of at least 1 kW per kilogram of the electrode; and a    (4) device (D3) comprising an electrode capable of converting at least 60% of the energy stored after a charging step to electricity during a discharge step, where the discharge step performed such that at least 50% of the capacity of the device is discharged within 1 second, and the discharge step is performed at a rate of at least 1 kW per kilogram of the electrode.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic diagram of the method for making an assembly of carbon-based nanostructures.    Substrate (10)    Layers (12, 16)    Carbon-based nanostructures comprising positively-charged functional groups (14)    Carbon-based nanostructures comprising negatively-charged functional groups (18)