Fuel cells and batteries are galvanic cells that play an important role in the energy transition taking place in industrialized countries (away from fossil, CO2-intensive and towards renewable energy sources).
Batteries, especially rechargeable secondary batteries (accumulators), are already making an important contribution to stabilizing power grids or supplying households, e.g. as electricity storage for regeneratively generated energy. The proportion of low-emission electric cars is also growing steadily in the automotive industry.
Unlike batteries, fuel cells are energy converters, not storage devices. They require a permanently supplied fuel (e.g. hydrogen or methane) to generate electricity. No CO2 is produced during direct energy generation and the advantage over accumulators is that the cell does not need to be recharged as long as fuel is available. Current applications for fuel cells include supplying heat and energy to buildings, operating off-grid devices (e.g. measuring stations) and powering very large vehicles (ships, trains).
Investment in both battery and fuel cell development is currently enormous: for batteries, research is currently focusing primarily on lifespan, energy density and charging behavior, while for fuel cells it is efficiency (catalyst effect). For both type of cell, the starting materials (electrode components, membrane materials and electrolytes) and their processing during the cell production process are particularly influential factors. This is precisely where we, 3P Instruments, offer suitable analytical measurement methods for determining important electrochemical and physical influencing parameters in order to optimize the manufacturing process and properties of the final galvanic cell.
Analytical 3P solutions for battery development
The development of rechargeable batteries with higher electrical power and a longer lifespan as well as more environmentally friendly production and disposal is one of the core topics of current battery development. In addition, the aim is to reduce manufacturing costs in order to make end products, e.g. in the automotive and home technology segments, affordable for as many customers as possible. There are currently various approaches in research for the development of new types of batteries such as all-solid-state, lithium-air or lithium-sulphur batteries, none of which are yet ready for series production. The most common system currently in use is the so-called lithium-ion NMC batteries (NMC: nickel-manganese-cobalt). They are used in key areas such as portable electronic devices (smartphones, tablets, notebooks) and in the entire field of e-mobility (electric cars, hybrid vehicles, electric wheelchairs).
The manufacturing process of a modern lithium-ion rechargeable battery is very complex and involves numerous production steps. Basically, the first step is the production of the anode, cathode, separator and cell housing, and the second is the cell assembly of these individual components. The properties of the starting materials and the production of the electrodes and separators from these are essential for the subsequent quality and performance of the final battery and this is where our analysis methods help you to find the best possible solution for your task.
Characterization of the source materials
Particle size and shape of the active materials: Active materials for manufacturing the electrodes of a lithium-ion battery include graphite, carbon black and lithium nickel manganese cobalt oxide (NMC). The separators are often coated with functional materials to improve their properties, e.g. with aluminum oxide to improve thermal stability. Currently, the coating process is usually carried out via the suspension route. The particle morphology of the starting powders, i.e. particle size distribution and particle shape, influences both the properties of the slurries and the quality and performance of the finished electrode or separator layer. Oversized particles can impair the homogeneity of the layer (uniform layer thickness, number of defects), the elongation of the particles (more platelet-rod-shaped or round) influences both the rheological properties of the suspension and thus its processability as well as the packing density and arrangement of the particles. It is in particular these properties that can be analyzed precisely and quickly with our Bettersizer series devices, in particular the Bettersizer S3 Plus, thanks to the unique combination of laser diffraction and dynamic image analysis. Read our 3P App-Note 4-04 for more information.
Electrical conductivity of the electrolyte: Liquid starting materials for the electrolyte are organic solvents such as dimethyl carbonate (DMC) or ethyl methyl carbonate (EMC), the anode paste is often water-based and N-methyl-2-pyrolidone (NMP) is usually used for the cathode slurry. Even small amounts of water can interfere with the electrolytes in particular, as this decomposes the conducting salt in the solvent and thus disrupts the functionality. The exact determination of electrical conductivity in organic media is easily possible with our DT-700 in the range 10-11 to 10-4 S/m. An example measurement curve for DMC can be found in our 3P App Note 6-01.
Examination of the electrode slurries: To produce the active electrode or separator layers, the functional particles are dispersed in a liquid medium using various tools/machines. Aqueous and organic liquids such as NMP (N-methyl-2-pyrrolidone) are used here. It is particularly important during processing that these dispersions are characterized in their original state with regard to their dispersion state (degree of agglomeration) and electrochemical properties such as zeta potential or electrical conductivity. Only in this way can the production process be fully understood and kept stable. In addition, it is important for the further development and improvement of battery cells to replace ecologically problematic components such as NMP, which is currently frequently used for electrode production, and to investigate alternatives with regard to the coating process. Our acoustic spectrometer DT-1202, which combines acoustic attenuation spectroscopy for particle size determination and electroacoustics for zeta potential measurement in one device, offers a comprehensive characterization of such dispersions with regard to dispersion state and the important electrochemical properties in the original concentrated state. The 3P App Note 6-01 summarizes various application examples of the DT-1202 for battery development.
Analytical 3P solutions for fuel cell development
The most important areas of application for fuel cells are currently the energy supply for buildings (especially in Japan) and the power supply for off-grid measuring stations or electrical appliances. Another segment with high future potential is the transportation of goods via large means of transport such as ships or trains, particularly in order to reduce the very high CO2 emissions. In order to make fuel cell technology competitive in this area, the aim of research and development is to minimize production costs while maintaining high product quality. Similar to the electrode production of lithium-ion batteries, liquid suspensions play a decisive role in the production of the important low-temperature polymer electrolyte membrane fuel cells (LT-PEMFC): the heart of the cell, the membrane coated on both sides with the catalyst (CCM), is produced via the suspension route. The CCM active in the cell is crucial for the most powerful power generation process possible and must be as stable as possible against ageing. The properties of the starting materials and the suspension are decisive factors for the quality requirements and our analytical methods help you to check and optimize these significantly.
Characterization of the source materials
Particle size of the starting powders of the catalyst inks: Both cathode and anode-side platinum-coated carbon substrates (usually carbon black) are used to produce the suspensions (catalyst inks) for coating the membrane (decal). The particle size distribution of these catalyst powders or the degree of agglomeration is an important factor influencing the processing properties of the catalyst ink and the subsequent anode or cathode layer. Our Bettersizer series devices – the Bettersizer S3 Plus or Bettersizer 2600 – are ideal for measuring the particle size distribution of micro- and sub-microscale powders using laser diffraction. Read our 3P App Note 4-04 for more information. For particle size determination of nano-platinum particles as a separate starting material, our BeNano series devices are available, which can characterize nanoparticles even in low concentrations on the basis of dynamic light scattering (DLS).
Investigation of liquid suspensions: To produce the catalyst inks, the active powders are dispersed in a liquid medium, usually a mixture of water, an alcohol (methanol, iso-propanol) and a binder (ionomer), using an intensive mixer (dissolver, paddle mixer, etc.). Good mixing of the components, no agglomeration of the particles and also specific dispersion properties such as viscosity and electrical conductivity are decisive for the quality of the subsequent active material layer. Similar to the characterization of battery slurries, our acoustic spectrometer DT-1202 with the combination of acoustic attenuation spectroscopy for particle size determination and electroacoustics for zeta potential measurement is ideally suited for a comprehensive analysis of the original concentrated suspension (see 3P App Note 6-01).
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