Cathode active materials synthesis using glycerol-based solvent for Li-ion and Na-ion batteries : preparation, characterization, and techno-economic analysis

This dissertation investigates cathode active materials (CAMs) synthesis using glycerol solvent for Li-ion and Na-ion batteries. Glycerol, which can be produced from biomass and is also a byproduct from the biodiesel esterification process, provides a green manufacturing route to produce CAMs. The use of glycerol to replace water makes the CAM production process environmentally friendly and cost effective. The research work in this dissertation establishes quantitative links between precursor formulation, particle formation mechanisms, long-term cycling behavior in coin cell batteries, and the techno-economic feasibility of the manufacturing process. The first part of research was focused on developing a physics-based model describing the evaporation and solidification of multicomponent precursor droplets containing glycerol, water, and ethanol. This work was aimed at understanding drying of sprayed glycerol droplets containing chemical precursors and other components. The model captures the transition from constant-rate drying to diffusion-limited crust formation and reproduces experimental single-droplet drying behavior. Under typical experimental drying conditions (50 µm initial diameter, 623 K air stream), the total drying time takes approximately 6–7 s. When ethanol is involved, increasing the ethanol concentration accelerates evaporation and reduces the crust-formation diameter from ~33 µm to ~31 µm, while glycerol-rich formulations prolong process due to higher glycerol viscosity and mass transfer resistance. These findings provide a mechanistic basis for interpreting hollowing and surface-instability features observed in spray-dried powders. The second part of research was focused on an experimental investigation of how water, ethanol, and ethylene glycol modify the behavior of glycerol-based precursor droplets and influence the morphology, structure, and electrochemical properties of spray-dried LiNi0.8Co0.15Al0.05O2 (NCA) using glycerol-based precursor solutions. It was found that ethanol increased the first-cycle discharge capacity from 140.6 mAh g⁻¹ (at 10 percent) to 181.4 mAh g⁻¹ (at 20 percent) and improved capacity retention to 90.1 percent in 120 cycles at 0.1 C rate. Further, it was found adding ethylene glycol (EG) to the precursor solution resulted in the best structural ordering at 10–15 percent EG, yielding an 89.2 percent retention. In contrast, a 20 percent water in the precursor reduced the first-cycle capacity to 127.9 mAh g⁻¹ and produced the lowest retention (78.2 percent). These results show that precursor compositions strongly influence the glycerol droplet drying behaviors, cation distribution, and electrochemical performance. The third part of research was focused on the synthesis of sodium transition metal oxide CAMs in a glycerol-assisted thermal decomposition route. In particular, the P2-type Na₀.₆₇Ni₀.₃₃Mn₀.₆₇O₂ and its Zr-doped derivative were studied. It was found that the Zr substitution slightly expands interlayer spacing and suppresses P2–O2 transitions, therefore stabilizing the P2 phase for better performance. The undoped material showed an initial capacity of 131.9 mAh g⁻¹ at 0.1 C but quickly faded to 64.9 mAh g⁻¹ after 200 cycles (0.3 C). The Zr-doped sample showed a lower initial capacity of 119.2 mAh g⁻¹ at 0.1 C, but maintained a capacity at 105.4 mAh g⁻¹ after 200 cycles (0.3 C), demonstrating a much enhanced structural stability. Finally, a two-step techno-economic analysis (TEA) was used to investigate the economic viability of Na-ion CAM powder production in the spray drying-based glycerol process. It was found that the minimum cathode-material selling price (MCSP) is most sensitive to precursor costs, plant scale, and discount rate. The chemical precursors, sodium acetate, nickel acetate, and manganese acetate, dominate material contributions, while optimized precursor concentration and increased throughput can markedly reduce MCSP. The TEA results indicate that the production process can achieve substantial cost reductions in both material and processing expenses compared to the conventional carbonate co-precipitation method. Sensitivity analysis reveals that the production process can lower the MCSP to $12.57/kg vs. $14.40/kg from the co-precipitation process. Additionally, every 20 percent reduction in material cost would result in a $1.39/kg decrease in the MCSP. Accordingly, manufacturing of Na0.67Ni0.33Mn0.67O2 from the spray drying process is particularly well-suited to meet the U.S. Department of Energy's battery cost target of $80/kWh, highlighting the promise of this process as a viable approach for Na-ion CAMs.