No abstract

Slug flow has received increased interest due to the slugs serving as individual microreactors for enhanced process efficiency and product quality. In this study, slugs were continuously generated in various scales and sizes, with slug size uniformity studied by in‐line imaging. Different strategies of gas flow control and slug scale‐up were evaluated regarding the slug size distribution. With modified gas flow control, the slug uniformity was improved significantly. Slug flow can also be scaled up without sacrificing slug size uniformity, either by increasing the reservoir feeding volume or the flow rate. The type of gas used (air and nitrogen) to generate slugs does not affect the slug size uniformity. A narrow slug size distribution can improve the particle size distribution and, hence, lead to better product quality.

Li[Ni0.8Co0.1Mn0.1]O2 (LNCMO811) is the most studied cathode material for next-generation lithium-ion batteries with high energy density. However, available synthesis methods are time-consuming and complex, restricting their mass production. A scalable manufacturing process for producing NCM811 hydroxide precursors is vital for commercialization of the material. In this work, a three-phase slug flow reactor, which has been demonstrated for its ease of scale-up, better synthetic control, and excellent uniform mixing, was developed to control the initial stage of the coprecipitation of NCM811 hydroxide. Furthermore, an equilibrium model was established to predict the yield and composition of the final product. The homogeneous slurry from the slug flow system was obtained and then transferred into a ripening vessel for the necessary ripening process. Finally, the lithium–nickel–cobalt–manganese oxide was obtained through the calcination of the slug flow-derived precursor with lithium hydroxide, having a tap density of 1.3 g cm–3 with a well-layered structure. As-synthesized LNCMO811 shows a high specific capacity of 169.5 mAh g–1 at a current rate of 0.1C and a long cycling stability of 1000 cycling with good capacity retention. This demonstration provides a pathway toward scaling up the cathode synthesis process for large-scale battery applications.

Lithium nickel manganese cobalt oxide (NMC111) is considered to be one of the most promising cathode materials for commercial lithium-ion battery (LIB) fabrication. Among the various synthesis procedures of NMC111, hydroxide co-precipitation followed by lithiation is the most cost-effective and scalable method. Physical and chemical properties of the co-precipitation product such as yield, particle size, morphology, and tap density, depend upon the various reaction parameters, which include pH, chelating agents, metal salt concentrations, and stirring speed. As a consequence, detailed theoretical and experimental modeling is critically required to not only understand the interdependence between the particle properties and reaction conditions but also optimize these parameters. In this study, theoretical modeling was performed to analyze the role of various NH 4 OH concentrations with varying pH on the yield of the NMC(OH) 2 product. From the experimental findings, it was observed that the product obtained at a pH of 11.5 and NH 4 OH concentration of 0.02 M possessed the highest tap density. Three of the hydroxide precursors with different tap density values were chosen to lithiate and were applied for coin cell fabrication. The NMC(OH) 2 precursor with the highest tap density had the highest specific capacity of 155 mAh g −1 at 0.1 C and retained up to 78.6 mAh g −1 at 5 C. The variation of the Li + diffusion coefficient for the three selected materials was also studied using electrochemical impedance analysis.

Cost-effective production of low cobalt Li-ion battery (LIB) cathode materials is of great importance to the electric vehicle (EV) industry to achieve the zero-carbon economy. Among the various low cobalt...

The microparticle quality and reproducibility of Li(Ni0.8Co0.1Mn0.1)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.

With expanding demands of lithium-ion batteries in portable electronic devices (e.g., smartphones, tablet PCs) and environmental-friendly vehicles (e.g., electric and/or hybrid vehicles), it is important to further improve safety, extend battery life, increase charge capacity, and reduce cost. A key missing component is effective and efficient manufacturing of complex active cathode materials at needed scales, such as nickel-cobalt-manganese (NCM) oxide microparticles with layered structures. Specifically, the material microparticle quality and uniformity have been difficult to control within the current reactors, thus extra correction procedures are needed, which risk product quality and reduce process efficiency. This study examines the innovative slug-flow continuous manufacturing process to directly produce well-controlled microparticles with advanced battery performance and accelerated scale-up, while enhancing fundamental understandings. The process utilizes a slug-flow reactor in which a multiphase mixture of liquid and gas in a tube spontaneously separates into slugs of liquid or slurry separated by slugs of gas. We have devised the milli-fluidic reactor and flow conditions so that hydrodynamically stable slugs form spontaneously immediately upon contact of the liquid and gas. Typical liquid/slurry slugs are 2-mm in length and 2-mm in diameter. In addition, we are able to selectively inject additional reactants in individual slugs to carry out the follow-on reactions. The sequential addition of the desired NCM precursors have allowed us to control the NCM radial profile in each particle. Microscopically, in a slug-flow reactor, each particle experiences the same environment with spatially uniform reaction conditions (kinetics, hydrodynamics) throughout the nucleation-growth process, leading to uniform particles with controlled composition and properties. Macroscopically, the manufacturing setup and conditions can remain the same while allowing convenient tuning of the production rate (scaling up or down). The electrochemical performance of the produced cathode particles is further enhanced by innovating coating treatment. Nonetheless, the technology/process equipment is being so developed that new battery chemistry can be easily incorporated with new future developments. Battery performance using NCM811 are tested and the results will be reported. Figure 1