Slug Flow Coprecipitation Synthesis of Uniformly-Sized Oxalate Precursor Microparticles for Improved Reproducibility and Tap Density of Li(Ni_0.8Co_0.1Mn_0.1)O₂ Cathode Materials

Abstract

The microparticle quality and reproducibility of Li(Ni_0.8Co_0.1Mn_0.1)O₂ (NCM811) cathode materials are important for Li-ion battery performance but can be challenging to control directly from synthesis. Here, a scalable reproducible synthesis process is designed based on slug flow to rapidly generate uniform micron-size spherical-shape NCM oxalate precursor microparticles at 25-34 °C. The whole process takes only 10 min, from solution mixing to precursor microparticle generation, without needing aging that typically takes hours. These oxalate precursors are convertible to spherical-shape NCM811 oxide microparticles, through a preliminary design of low heating rates (e.g., 0.1 and 0.8 °C/min) for calcination and lithiation. The outcome oxide cathode particles also demonstrate improved tap density (e.g., 2.4 g mL^-1 for NCM811) and good specific capacity (202 mAh g^-1 at 0.1 C) in coin cells and reasonably good cycling performance with LiF coating.