Driven By Power

The world is driven by power – electrical power!  Batteries are essential elements powering our day-to-day life, from cell phones and electric vehicles to grid energy storage. And innovation drives the battery industry, with researchers and manufacturers developing new materials that perform better, are safer, and cost less.

In the past 10 years, there has been a significant move towards more environmentally friendly transportation options, and governments worldwide have introduced policies and incentives to promote the use of battery-powered energy. As a result, there is now an unprecedented demand for batteries that are both more efficient and cost-effective. Waters’ TA Instruments division is working with our customers to help them develop novel materials and optimize battery manufacturing processes for efficiency and sustainability.

Powering your world

Lithium-ion batteries power most electric vehicles (EV) around the world today. EV battery manufacturers employ the full breadth of our technology (thermal analysis, rheology, and microcalorimetry) to ensure that their batteries are safe, efficient, durable, and can be recycled appropriately. From a comprehensive analysis of lithium-ion battery materials to help battery producers select the right components to screening battery chemistries, we’ve been working with three of the top five leading electric vehicle manufacturers to increase performance, lower cost, and ensure the continued safety of lithium-ion batteries.

A lithium-ion battery is a complex system with multiple materials acting together to generate precise electrochemical processes. A functional battery requires:

• A cathode and an anode to facilitate the reversible exchange of ions.
• Electrolytes to serve as a conductive medium.
• A separator to prevent internal short circuits.

As the EV battery value chain becomes more complex and vertically integrated, our technologies will continue to solve key research and testing needs for this rapidly growing industry.

The science behind a battery charge

Understanding how internal materials interact physically and chemically during a battery’s operation is critical to determining the long-term performance of a battery.

The heat generated when the battery is being charged (e.g. when an EV is plugged into its charging station) and discharged (e.g. when an EV is driving along the road) is associated with the electrochemical reactions in the battery cell. It is crucial to differentiate between the heat generated by the battery’s electrochemical energy storage reactions and the parasitic side reactions that cause capacity loss and increased waste heat generation. This will measure the efficiency of the cell chemistry (how much of the stored energy is lost to side reactions) and how quickly the cell will degrade with continued operation.

TA Instruments’ Battery Cycler Microcalorimeter Solution is a non-destructive technique that enables researchers to perform high-resolution, in-operando measurements of the heat flow during electrochemical cycling. Using a TAM IV Microcalorimeter and TAM Assistant Software integrated with a BioLogic VSP-300 Potentiostat, this platform can deliver accurate and rapid detection of parasitic reactions, which can be used to screen new battery formulations or identify defective cells.

Ensuring the safety of the critical components of a battery

Improving safety is another aspect of battery development. Exothermic reactions that cause the battery’s operating temperature to rise unpredictably may lead to thermal runaway, which is a uncontrollable self-heating event that typically leads to a fire.

Thermal analysis including thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) are essential techniques used to determine thermal stability, including the onset of an exothermic reaction and the heat of reactions for battery materials. The onset and amount of heat released during the exothermic reaction can help a battery engineer to design thermal management systems and perform a safety evaluation of cathode and anode materials in different states of charge.

The battery separator is one of the most critical components to ensure battery safety.

• A separator is a porous or ionically conductive polymeric membrane that prevents physical contact between the cathode and anode while allowing ion transport.
• Multiple techniques can be used to conduct thermal analysis of a battery separator to ensure they possess the required thermal and mechanical stability to prevent an internal short circuit.
• Dynamic Mechanical Analyzers (DMA) can be used to measure mechanical properties to ensure higher temperature mechanical stability.

Mechanical properties are also important for high-strength composites, which are often used in battery casings and module/pack materials. In addition to the modulus and strength, mechanical fatigue testing is critical for evaluating fatigue life (mechanical cycle to failure) and helps researchers to develop high-durability materials.

Optimizing battery products to save money

Electrode manufacturing accounts for 20-40% of the total battery pack cost. It involves mixing active materials, binder, and conductive additive into a slurry (an organic solvent of the mixed materials), then coating and drying on the current collector. Incoming material quantification and slurry characterization help to save manufacturing time and cost. Rheology is one of the best technique for evaluating raw materials, slurry stability, and processability when optimizing the electrode manufacturing process. Rheological evaluation of battery slurries reveals the change in characteristics under applied stress or force.

What’s on the horizon in battery development

Dry battery electrode (DBE) processing and solid-state batteries are next on the battery industry development front to reduce cost, increase energy density, and improve safety.

The challenges of processing powder into thin films require understanding the adhesive mechanisms, dry mixing, and scale-up processes. Waters-TA’s Powder Rheology solution measures powder cohesive properties, yield strength, flowability, and compressibility, which provides insights into powder processing that can aid in overall manufacturing efficiency and waste reduction.

Improvements in chemistry and manufacturing will continue to accelerate battery technology. We believe demand for more durable, safer, and cheaper ingredients in batteries will continue to grow; we will continue to support innovation and help deliver new products to the market faster. The biggest breakthroughs may be just around the corner, and we’ll be there to drive science forward.

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References

• Battery Cycler Microcalorimeter Solution – TA Instruments
• Determination of Parasitic Power in Lithium-ion Batteries using the Battery Cycler Microcalorimeter Solution – TA Instruments
• The Impact of Electrolyte Additives in Lithium-ion Batteries Determined Using Isothermal Microcalorimetry – TA Instruments
• An Overview of Isothermal Microcalorimetry in Battery R&D and QA – TA Instruments
• Safety Evaluation of Lithium-ion Battery Cathode and Anode Materials Using Differential Scanning Calorimetry – TA Instruments
• Thermal Analysis of Battery Separator Film – TA Instruments
• Battery Separator Film Development: Impact of Coating – TA Instruments
• Hawley, W. B., Li, J. Electrode manufacturing for lithium-ion batteries—Analysis of current and next generation processing. Journal of Energy Storage 25 (2019) 100862
• Rheological Evaluation of Battery Slurries with Different Graphite Particle Size and Shape – TA Instruments
• Time Dependent Stability of Aqueous Based Anode Slurries with Bio-Derived Binder by Rheological Methods – TA Instruments
• Science Direct