**4. Conclusions**

Although physical experimental data are not presented for the theoretical design and resulting variation, it is understood that all manufactured parts, whether in industry or academia, will have an associated deviation from the target value. This variation in the produced parts may be the result of the non-uniformity of laboratory scale calender rolls, or the industrial manufacturing process where parts are presented as having a target value and accepted tolerance range. In either scenario, the produced parts may be deemed acceptable. Progressing forward, the manufacturing tolerance can be reduced through the use of high precision coating and calendering equipment. The reduction in these process tolerances will have a dramatic e ffect on lithium ion cell electrode porosity and matching ratio consistency, which inevitably a ffects repeatable cell capacity, cycle life, rate capability, safety, as well as many other important characteristics of lithium ion cells.

A simple look at the electrode manufacturing process and the correlation to electrolyte volume may o ffer a quick explanation into cell-to-cell or lot-to-lot variation observed in di fferent lithium ion cell manufacturing and quality control processes. While this process was applied to a generic positive and negative electrode formulation at di fferent loadings, the analysis and resulting porosity, void volume, and matching ratio variation calculations can be applied to any electrode manufacturing process. As electrode design moves toward higher energy designs with a higher percentage of active material or thinner, higher power electrodes, the effect of these variations is increased.

For the selected 93% LCO positive electrode and 92% active carbon negative electrode, a coating tolerance of ±0.4 mg/cm<sup>2</sup> and a calender tolerance of ±3.0 μm was used. For the high power/low energy positive and negative electrode target loading of 10 and 5.56 mg/cm2, respectively, a porosity range of 19.6% to 38.6% and 30.8% to 48.0% for a nominal 30% and 40% porosity positive and negative electrode is possible. Also shown is an equal area negative to positive cell matching ratio range of 0.98 to 1.23, for a target value of 1.1.

**Funding:** This research received no external funding.

**Acknowledgments:** Work has been partially supported by the Penn State Hazleton Research Development Grant. **Conflicts of Interest:** The authors declare no conflict of interest.
