Energy storage and energy conversion devices are both used to fill the need for portable as well as renewable power. The evolving needs require the improvement in capability to provide pulse-power, long run-time and cycle life. New materials and advancements of engineering play a key role in meeting the market demand.
Li-ion batteries are today’s leading technology in this space. Cyclic voltammetry is used in the development of the material and identification of its potential window (charge cut-off voltage and discharge cut-off voltage), and is also the primary technique in identification of new electrolytes. The BNC connections of both the Solartron Analytical EnergyLab and Princeton Applied Research potentiostats provide an interface common for the glovebox feedthroughs often needed for this type of research.
As the goal of a rechargeable battery is to provide high cycle-life, high efficiency, and high energy density, prospective new materials are combined into a complete cell and tested in a charge – discharge experiment to determine the capacity vs cycle number, cycle-life and Coulombic efficiency. Battery holders for PARSTAT and VersaSTAT potentiostats allow for direct connection of common battery formats to the instrument. Direct connection through a battery holder avoids the added stray capacitance and inductance to impedance measurements, and creates a cleaner signal and a cleaner lab.
The use of auxiliary voltage measurements allows monitoring of both the anode and cathode of a battery. Standard potentiostat design concentrates on the signal and response at the Working Electrode, and the Counter Electrode reactions are not characterized. Other applications use an inert Counter Electrode, but in battery technology this is an active electrode. Being able to characterize this terminal allows users to identify failure mechanisms and properly focus research initiatives. This is available on the PARSTAT 3000A and EnergyLab products for single cell evaluation and PARSTAT MC for multichannel, simultaneous tests for improved throughput.
The typically flat-voltage profile, seen as a key advantage of Li-technology, drives the need for advanced techniques to determine State of Charge. Electrochemical Impedance Spectroscopy (EIS) is the emerging method for making these determinations in-situ. EIS is also used to determine how the battery is functioning with respect to its anticipated lifetime (State of Health). The full range of products from Princeton Applied Research and Solartron Analytical provide these measurement capabilities either as standard or as options. EIS also provides a mechanism via equivalent circuit analysis or simple visual reference to identify the Equivalent Series Resistance (ESR) of a battery. This is a key figure of merit as it represents a loss of the system. The EnergyLab EIS methods, including its innovative FRA-technology and oversampling, allows for characterization of devices of micro-ohm impedance.
For extreme applications that require greater than 5 V or 2 A of current, batteries can be configured in stacks. Since stacks are purposefully designed for operation at high voltages (up to 100 V) or high currents (up to 100 A), external boosters are required. External boosters are available in a wide range of measurement capacities, bandwidth and accuracy to meet a given testing profile. The PMC-2000A and PARSTAT3000A provide the voltage range to test a stack of batteries as well as the standard, additional electrometer to measure the characteristics (including impedance) of a single battery within the stack. The EnergyLab provides multiple electrometers to study even more cells within the stack.
Whatever your requirements in state-of-the-art energy storage and energy conversion applications, AMETEK’s Princeton Applied Research and Solartron Analytical advanced instrumentation provides the tools for market leading impedance analysis, with the widest voltage and current ranges available for anode/cathode and stack testing.