Dataset: Quantitative separation of thermal and electrochemical contributions in NLEIS measurements

This dataset provides experimental nonlinear electrochemical impedance spectroscopy (NLEIS) measurements for a Molicel INR18650-M35A lithium-ion battery, supporting the research article published in the Journal of Power Sources (https://doi.org/10.1016/j.jpowsour.2026.240924). The data enables investigation of battery linearity thresholds, nonlinear behavior characterization, and validation of impedance measurement protocols across various operating conditions. A key contribution is the separation of electrochemical nonlinearity from thermal effects during NLEIS measurements, achieved through auxiliary high-frequency impedance measurements that enable continuous internal cell temperature estimation. For detailed information about data structure, experimental protocols, and data processing methodologies, refer to the README.md file included with the dataset.