Supercapacitors

In the field of “Supercapacitors”, we are researching the characterization of battery materials and optimization methods with regard to electrode and battery cell production.

Electric double-layer capacitors (EDLCs) are devices based on Carbon/Carbon-based electrodes and have the characteristics of being charged and discharged very fast (within seconds) and can therefore be used where high power is required. Despite the high-power capability, these devices have limitations in energy density. 

One of the strategies to enhance the energy density is to design a hybrid system where one of the electrodes is a capacitive one (e.g. activated carbon) and the other electrode is a faradaic one (e.g. a battery material).

This includes:

• Lithium-ion capacitors – also called asymmetric capacitors or superbatteries – are typically based on a graphite or Li₂Ti₅O₄ negative electrode (the faradaic electrode) and an activated carbon positive electrode (the double layer-type electrode) and already found a niche in the market.
• Sodium-ion capacitors where the faradaic electrode is typically represented by hard carbon can represent the next generation of more sustainable high-power energy storage devices.

Differently than lithium- or sodium-ion batteries, these types of devices don't contain a lithium or sodium source at the positive electrode and therefore strategies of pre-metallation need to be considered.

Our R&D-Services on the Topic »Supercapacitors« Include:

• Characterization of Materials and Components and Performance Evaluation in EDLC Configuration at Lab-Scale Cells
• Optimization of Electrode Recipe via Aqueous and Dry Electrode Preparation
• Study of Asymmetric Configurations (Li-, Na-, but Also K-ion Capacitors) via Mass Balancing and Pre-Metallation Strategies
• Electrode Processing Scale-Up and Tests in Pouch Cell Format Configuration

Laboratory scale cells in different geometries and configurations (Swagelok^®-type, coin cells, EL-Cells with two- or three-electrode configuration) will be used to evaluate electrodes and cell components (e.g. activated carbon, binder, separator, electrolyte, additives etc.). Different electrochemical techniques can be used such as cyclic voltammetry, galvanostatic charge/discharge, electrochemical impedance analysis, constant power discharge tests as well as electrochemical quartz microbalance and electrochemical dilatometer. Pre- and post-mortem analysis via SEM including EDS, BET analysis, ICP-QES analysis, ICP-OES analysis, XPS, and Raman spectroscopy can be done on materials, electrodes and electrolytes. We are performing the electrochemical analysis in both organic and aqueous electrolytes.

Based on our long-standing experience in electrode processing we are developing slurries and electrode coatings procedures tuned to the particular material. Furthermore, we are developing electrode processing via environmentally friendly routes with aqueous processing or dry processing (solvent-free). The electrode preparation can be monitored via Physical-morphological characterization (porosity measurements, adhesion test, SEM including EDS analysis, etc.) and correlated to electrochemical performance in lab-scale cells. 

Besides the classical symmetric EDLC, we offer studies of asymmetric configurations either based on asymmetric carbon//carbon devices or battery-type/carbon configurations where one electrode can be a lithium-, sodium-, or potassium-based insertion material and the other a typical double layer-electrode (also called metal-ion capacitor or superbattery). We are optimizing the mass balancing of the electrodes and apply different pre-metallation strategies based on sacrificial salts.

We can provide electrode processing scale-up and further testing within mid-scale cells in a pouch cell configuration. Our expertise includes the development and optimization of electrode formulations, coating techniques and drying processes tailored to large-scale production. Within our facilities we can evaluate the electrochemical performance, cycle life and safety characteristics of EDLC in pouch cell formats.