Application note

Liquid flow controllers in battery manufacturing

In the lithium-ion battery manufacturing process, mass flow controllers are used to batch-dose electrolyte in a long-life lithium-ion battery for the best lifetime and the highest capacity.

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In the current energy transition from fossil fuels to sustainable energy sources, lithium-ion batteries are popular with respect to energy storage. They charge and discharge, to supply power for electrical vehicles and mobile computer devices.

In lithium-ion batteries, the electrolyte is a medium that transports charge-carrying lithium ions between the electrodes of these devices, effectively enabling charging and discharging. One of our customers, a leading supplier of production machines for lithium-ion batteries, requested Bronkhorst to supply mass flow devices to accurately fill liquid electrolyte material into battery cells as part of the battery manufacturing process.

Mass Flow Controller in battery manufacturing

Application requirements

A consistent, continuous, or cyclic battery filling process needs to take place at a low working pressure or vacuum in a very dry environment to ensure homogeneous distribution of the electrolyte inside the pouch-shaped battery. Accurate control of the electrolyte quantity is a key requisite.

Important topics

  • Optimal amount of electrolyte is supplied due to the high accuracy of the flow controller
  • Real mass flow control in real time
  • Logging of each batch dose for transparency purposes

Process solution

In the application, the electrolyte is filled into the battery cell under vacuum with a high precision dosing needle. (Partial) filling is repeated several times depending on the manufacturer and cell type.

To fill the pouch-type battery cells, a parallel arrangement of multiple M15 mini CORI-FLOW control units and special valves designed by the customer is connected to the electrolyte supply vessel. Here, the pressure is controlled by an EL-PRESS type P-800 pressure controller at a constant value of 0.5 bar(g).

The electrolyte, typically a little bit denser and more viscous than water, is drawn into the battery cell that has been vacuumised prior to filling. For a good distribution of the electrolyte inside the battery, it takes 3 to 15 seconds to fill the battery with 20 to 150 ml of electrolyte, depending on the battery size.

Flow Controller in battery manufacturing
Flow scheme

The flow controller supplies the optimal amount of electrolyte due to the high accuracy of the instrument. This will positively affect the final battery performance.

The mass flow controller allows for real mass flow measurement and control in real time, eliminating the need for a weighing scale and avoiding the use of a pump that cannot indicate the real flow. Moreover, each batch dose can be logged, allowing for transparency. This is important for the internal quality control during manufacturing, but also for possible recalls in the future to be able to determine root causes for defective batteries, if any.

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Flow devices for battery manufacturing


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