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Lithium-ion battery manufacture involves some processes where oxygen monitoring is critical. For Cathode Active Material (CAM) production, oxygen in calciners should be precisely controlled.
For nickel, cobalt, manganese (NCM)-type cathodes, CAM is made through the reaction of the precursor product, PCAM, and lithium hydroxide/lithium carbonate in a rotary calciner. Oxygen must be fed during calcination to ensure the desired CAM crystal structure, but conditions make oxygen monitoring difficult.
This application note looks at the need to monitor and control oxygen concentrationduring calcination and METTLER TOLEDO's solution for coping with this tough environment.
The cathode in Li-ion batteries comprises a layer of fine lithium metal oxide salt, cathode active material. The performance of Li-ion batteries with respect to thermal stability, energy density, charging, and discharging depends largely on preventing entrained impurities, plus the uniformity in distribution, size, and crystal shape of the CAM particles.
Cathode active material calcination is a two-step heat treatment where two solids react to form the CAM. Calcination temperature, time, and oxygen atmosphere all play an important role and are continuously being researched. What is widely agreed is that oxygen non-stoichiometry can affect the CAM’s crystal structure and electrochemical performance. Therefore, oxygen concentration in the calciner should be tightly controlled.
Oxygen is measured in the calciner's vent gas, but high temperature, varying gas composition, and the presence of moisture and dust make O2 measurement difficult. METTLER TOLEDO's tunable diode laser (TDL) spectrometer, the GPro 500 provides highly reliable performance in this application. Whether used in situ or in an extractive situation, the GPro 500, helps ensure CAM crystal structure always has the desired properties.
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