Paper Title: Variability in initial battery cell characteristics and its implications for manufacturing quality control
Authors: Coskun Firat
Corresponding Author: Coskun Firat (coskun.firat@itu.edu.tr), Turkey
Abstract
Ensuring manufacturing consistency in lithium-ion batteries is critical for reliable performance, safety, and longevity. This study examines the variability in initial pouch cell characteristics, including voltage, current, charge capacity, and discharge capacity, across 192 samples from 24 batches. Statistical analysis reveals that voltage remains relatively stable (mean = 3.951V, CV ≈ 6.45%), while charge and discharge capacities exhibit moderate variability (mean = 2.286Ah, CV ≈ 47.99% and mean = 2.350Ah, CV ≈ 52.53%, respectively). Current demonstrates the highest variability, with a mean of 0.280A and a CV of 195.25%, suggesting significant fluctuations possibly due to non-constant current and also likely influenced by process inconsistencies, operational conditions, or measurement sensitivity. Box plot and control chart analyses link many outliers to specific production factors, such as raw material lot changes and equipment maintenance cycles, pinpointing electrode preparation and formation as critical stages for mitigating variability. By integrating statistical insights with practical manufacturing considerations, this work provides a framework for proactive quality control, ultimately supporting scalable and high-quality lithium-ion battery production. While this study focuses on pouch cells, the underlying principles of variability analysis and targeted process improvements remain broadly relevant to other battery formats.
Keywords
Lithium-ion battery variability, Manufacturing process consistency, Pouch cell quality control, Initial cell characteristics, Statistical process monitoring
