In the current landscape, the demand for lithium-ion batteries is skyrocketing. From smartphones to laptops to electric cars, these batteries are at the heart of our daily lives.
The journey to produce a high-quality lithium-ion battery begins with the production of cathode active material, or more precisely, the precursor cathode active material (PCAM). A key element in PCAM production is pH control, and getting it right can make all the difference.
Let’s take a moment to look at why pH levels are so crucial in PCAM production. The quality of the cathode active material depends on the morphology (size, shape, and structure) of the CAM particles, as this directly impacts the energy density of the battery and how fast the battery charges and discharges.
CAM particle morphology is reliant on PCAM particle morphology, and if the particle sizes and shapes aren’t just right, you could end up with a battery that underperforms or even fails.
Maintaining very tight pH control during PCAM production is essential for achieving the specific particle sizes that ensure that the batteries, and ultimately the cars and devices we need, are efficient and reliable.
The figure (H. Muramatsu; D. Endo; T. Sasaki) shows how pH affects particle size distribution.
Here’s where it gets really interesting: the quality of lithium-ion batteries hinges on how well we maintain our pH control. Even a slight change in pH - say, 0.2 pH units - can lead to significant differences in battery performance.
A reliable, well-maintained pH sensor helps ensure the right particle size and morphology are achieved, directly translating into better battery charging, discharging, and overall battery life.
The particle size of PCAM significantly influences lithium-ion battery performance. Smaller particles offer higher surface area and faster lithium-ion diffusion, improving rate capability and charging speed. However, they may also increase side reactions and reduce cycle life due to surface instability. Larger particles enhance tap density and energy density but can limit lithium mobility, reducing performance at high rates.
Optimal PCAM particle size balances energy density, cycle life, and rate capability. Tailoring this parameter is crucial for applications ranging from electric vehicles to portable electronics, where both efficiency and durability are essential for long-term battery performance.
While the importance of accurate pH control is clear in PCAM production, many manufacturers encounter some significant challenges along the way. First of all, many of the reactors used in this process are based on designs from the 1990s. This means they often come with outdated pH sensor assemblies that are mounted from the top of the reactor or crystallizer. This design creates a few headaches:
The production and refinement of PCAM involves some highly critical process steps. This on-demand webinar looks at the vital role of pH and some other key process variables in determining PCAM quality and Li-ion battery production.
So, how can manufacturers tackle these challenges head-on? Here are a few suggestions:
Whereas pH sensors with a ceramic reference diaphragm fail rapidly due to fast clogging of the diaphragm’s microscopic pores, the InPro 4260i’s solid polymer reference electrolyte allows an open junction that, as it is much larger in size than the microscopic pores in a ceramic diaphragm, is far less prone to clogging. To a certain extent, it’s even self-cleaning in agitated processes. After longer process runs, it offers much better cleanability, and scale and build-up of material are easily removed from the junction.
These sensors provide real-time performance data, allowing maintenance to be executed based on actual needs rather than a set schedule. This fully predictive approach greatly helps in avoiding unnecessary maintenance without risking process upsets.
This is of great value for allocating staff and ensuring the timely ordering of consumable parts.
With these systems in place, operators merely need to refill cleaning solutions occasionally, freeing them up for more complicated tasks. At the same time, sensors are kept in the best condition and total measurement performance is maximized.
METTLER TOLEDO has developed a retractable, side-mounted, and completely automated solution. The EasyClean 500 automatically retracts the pH sensor from the process, then rinses, cleans, and even recalibrates it when needed.
"Maintenance is completely automated, so technicians only need to refill the cleaning acid and buffer solutions for calibration," says Stefan van der Wal. Through its loop-powered HART transmitter, the EasyClean 500 offers multiple program options so sensors can be either rinsed, cleaned, or calibrated automatically when needed, or maintenance can be performed remotely from the control room through the distributed control system (DCS).
Users can also give a command to the system to retract the sensor for remote verification to ensure that the sensor is providing an accurate measurement. "Quite honestly, says Stefan, EasyClean 500 is a significant way forward to high-quality cathode active material."
Stefan van der Wal has a degree in Industrial Management and Chemical Engineering. He has over 25 years of experience in the field of process instrumentation and liquid and gas analytics in process industries.
As Head of the Industry Marketing Department at METTLER TOLEDO Process Analytics, Stefan has consulted with the world’s largest chemical and refining companies regarding best practice industrial process control. He is strongly involved in application engineering and product development and is behind the design and commercialization of various revolutionary new process analytical products and technologies.
Learn how an automated pH sensor cleaning system is helping to provide enhanced battery performance.
In this Ask the Expert, Stefan van der Wal explains how METTLER TOLEDO's innovative pH measurement solution for lithium-ion battery manufacturing overcomes conventional limitations.
As we navigate the challenges of pH control in the lithium-ion battery manufacturing landscape, it’s crucial for manufacturers to rethink their strategies and the design of their process equipment. By adopting innovative sensor technologies and automated maintenance solutions, manufacturers can greatly enhance production efficiency and product quality.
The journey to producing high-performing batteries might have its bumps, but with the right tools, you can smooth the path ahead.
If you're eager to explore the world of intelligent pH measurement and automated maintenance solutions that can elevate your processes, check out the latest advancements available today.
Read more about all solutions for battery characterization, production, and testing.
