Meso-nano and micro-nano ion transport in porous carbon composite electrodes for energy storage applications

In energy storage devices carbonaceous composite electrodes are a popular choice, consisting of activated carbon (ac), conductive additives and a polymeric binder matrix. The active electrode components are in the form of ac particles, ac fibres, or ac monolith combined with conductive additives such as carbon black. Activated carbon plays the most important role for storing a large amount of energy in the form of ions contained in the carbon nanopores. This study considers a modelling approach to the meso-nano and micro-nano infiltration of ions into the porous carbon structure during the operation of the energy storage device. Depending on the pore size, ion size and solvent molecule size, ions may be solvated or unsolvated as they move, where ions are solvated in meso-pores for most cases. Molecular model simulations have been performed to determine the values of the geometrical parameters of different ions, solvated and unsolvated in various solvents. A meso-nano and micro-nano ion infiltration model has been developed in this study under both steady state and dynamic conditions

Meso-nano and micro-nano ion transport in porous carbon composite electrodes for energy storage applications

In energy storage devices carbonaceous composite electrodes are a popular choice, consisting of activated carbon (ac), conductive additives and a polymeric binder matrix. The active electrode components are in the form of ac particles, ac fibres, or ac monolith combined with conductive additives such as carbon black. Activated carbon plays the most important role for storing a large amount of energy in the form of ions contained in the carbon nanopores. This study considers a modelling approach to the meso-nano and micro-nano infiltration of ions into the porous carbon structure during the operation of the energy storage device. Depending on the pore size, ion size and solvent molecule size, ions may be solvated or unsolvated as they move, where ions are solvated in meso-pores for most cases. Molecular model simulations have been performed to determine the values of the geometrical parameters of different ions, solvated and unsolvated in various solvents. A meso-nano and micro-nano ion infiltration model has been developed in this study under both steady state and dynamic conditions

High-performance Supercapacitor cells with Activated Carbon/MWNT nanocomposite electrodes

The purpose of this work was to investigate and improve the performance of supercapacitor cells with carbon-based nanocomposite electrodes. The electrode structure comprised activated carbon (AC), four types of multi-wall nanotubes (MWNTs) and two alternative polymer binders, Polyvinyl alcohol (PVA) or Polyvinylidene fluoride (PVDF). Electrode fabrication involved various stages of mixing and dispersion of the AC powder and carbon nanotubes, rolling and coating of the AC/MWNT/binder paste on an aluminium substrate which also served as current collector. The organic electrolyte utilised was 1M tetraethylammonium tetrafluoroborate (TEABF4) fully dissolved in propylene carbonate (PC). All devices were of the electrochemical double layer capacitor (EDLC) type, incorporating four layers of tissue paper as separator material. The surface topography of the so fabricated electrodes was investigated with scanning electrode microscopy (SEM). Overall cell performance was evaluated with a multi-channel potentiostat/galvanostat/impedance analyser. Each supercapacitor cell was subjected to Cyclic Voltammetry (CV) at various scan rates from 0.01 V/s to 1 V/s, Charge-Discharge at a fixed current steps (2 mA) and Electrochemical Impedance Spectroscopy (EIS) with frequency range from 10 mHz to 1 MHz. It was established that an AC-based supercapacitor with 0.15%w/w MWNT content and 30 μm roll-coated, nanocomposite electrodes provided superior energy and power and energy densities while the cells was immersed in the electrolyte; well above those generated by the AC-based EDLC cells

A simple route towards next-gen green energy storage by fibre-based self-supporting electrodes and a truly solid polymer electrolyte

To meet the challenge of a green energy economy that could offer the chance to escape from our dependence on fossil fuels, the rapid development of materials science and technology is vital. Nowadays, advanced devices that convert and store energy are the focus of intensive research that is being carried out along various avenues and Lithium-ion batteries (LIBs) in combination with fuel cells and supercapacitors hold the promise for a clean solution for an electric future. Currently, there are a number of efforts underway to develop lithium cells by using renewable resources, to simplify the fabrication processes to lower the costs, and to use water as solvent to reduce the environmental impact. An increased attention is also devoted to the recycling of spent LIBs even though the assessment of the real balance between the economic and environmental impact of this process is still matter of debate. In this respect, a novel and original Li-ion cell architecture is here successfully developed for the first time by exploiting the use of carbonized cellulose nanofibrils as both conductive binder and current collector substrate. The cellulose nanofibrils are also used as a reinforcing agent for the preparation of an unconventional composite polymer electrolyte as separator. The truly solid lab-scale Li-ion cell, assembled in a “pouch cell”, demonstrates remarkably stable cycling characteristics upon prolonged cycling at ambient temperature. The outstanding results are obtained along with the implementation of a pilot line procedure, comprising the spray coating and water-based papermaking techniques. Noteworthy, the battery components after use can be fully recovered using paper recycling techniques, which will definitely open up a truly new way of conceiving advanced sustainable batteries