Automated electrolyte formulation and coin cell assembly for high-throughput lithium-ion battery research

Data-driven experimentation can accelerate battery research dramatically by closing the experimentation–analysis loop. Experimentation in traditional battery research is acknowledged to be heavily time-consuming and often suffers from large cell-to-cell variations. For closed-loop approaches, however, reliable and rapid performance evaluation is vital. Automation promises to enhance both the rate of testing and reproducibility. Herein, we present ODACell, an automated electrolyte formulation and battery assembly system, capable of preparing large batches of coin cells. We demonstrate the feasibility of Li-ion cell assembly in ambient atmosphere by preparing LiFePO4 || Li4Ti5O12 –based full cells with dimethyl sulfoxide–based model electrolyte. Furthermore, the influence of water is investigated to account for the hygroscopic nature of the non-aqueous electrolyte when exposed to ambient air. Reproducibility tests demonstrate a conservative fail rate of 5%, while the relative standard deviation of the discharge capacity after 10 cycles was 2% for the studied system. Electrolytes with 2 vol% and 4 vol% of water showed overlapping performance trends, highlighting the nontrivial relationship between water contaminants in electrolytes and cycling performance. Thus, reproducible data are essential to ascertain whether or not there are minor differences in performance for high-throughput electrolyte screenings. ODACell is broadly applicable to coin cell assembly with liquid electrolytes and therefore presents an essential step towards accelerating research and development of such systems.