Reducing the cost and improving the performance of lithium-ion batteries (LIBs) are crucial for their applications in transportation electrification and grid energy storage. Much research effort has been devoted to develop novel synthesis methods for LIB cathodes, since traditional methods such as coprecipitation suffer from long synthesis time and complex steps. In contrast, flame spray synthesis (FSS) has great potential for manufacturing LIB cathode materials due to its continuous, fast, and scalable operation. Nevertheless, FSS also faces challenges in controlling the morphology and improving the electrochemical performance of cathode materials for high energy density LIBs. For example, conventional FSS methods usually produce nanoscale particles with low volumetric density that limits their application in high energy density LIBs. In the current work, the effects of urea and polyvinylpyrrolidone (PVP) additives on the morphology and electrochemical performance of Li(Ni0.8Co0.1Mn0.1)O2 (NCM811) cathode materials synthesized by FSS were investigated. The current FSS setup used ultrasonic atomization to generate uniform droplets that passed through a low-temperature heating section and a high-temperature flame section. The loading of PVP was adjusted in a range between 0 wt.% and 2 wt.%, whereas that of urea was between 0 wt.% and 5 wt.%. Synthesized NCM811 materials with and without additives were characterized with X-ray diffraction (XRD) and scanning electron microscopy (SEM). Moreover, the electrochemical performance tests, including charging/discharging, cycling, and rate performance were conducted using 2032-type half-cells. XRD results confirmed that all NCM811 samples had layered structures. SEM and electrochemical tests showed that the samples without additives had hollow shell structures and a relatively low capacity retention ratio at a high rate of 1C (200 mA/g). In contrast, SEM results showed that an appropriate amount of urea addition was efficient in altering the particle morphology, especially the hollow shell structure. Nevertheless, excess urea addition worsened the uniformity of particles due to its negative effects on atomization. Moreover, the electrochemical performance was worsened as excess urea was added. In contrast, the samples synthesized with PVP as the additive demonstrated an improved electrochemical performance such as a higher discharge capacity and improved capacity retention. Similar to the samples obtained with urea addition, excess PVP addition resulted in nonuniform particles and a hollow structure. The current work revealed that a small amount of additives effectively optimized the morphology and performance of cathode materials synthesized using FSS. Therefore, the current method has great potential for further development due to the low-cost and easy-control of the additives.

Flame Spray Synthesis of Morphology Controllable and Performance Enhanced li(ni0.8co0.1mn0.1)o2 Cathode Materials Using Urea and Polyvinylpyrrolidone as Additives

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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