This dataset accompanies the manuscript “Electrochemical reversibility revealed by bipolar perturbations for chemistry-inclusive retired lithium-ion battery diagnostics.” It contains retired lithium-ion battery testing data together with the processed data products used for feature extraction, diagnostic analysis, and model development. The dataset supports a chemistry-inclusive workflow for studying electrochemical reversibility under bipolar perturbations and for building data-driven battery diagnostic models. It is intended to enable transparent reuse of the experimental data, processed features, and computational workflow associated with the study.