Theoretical Impact of Manufacturing Tolerance on Lithium-Ion Electrode and Cell Physical Properties

Abstract

The range of electrode porosity, electrode internal void volume, cell capacity, and capacity ratio that result from electrode coating and calendering tolerance can play a considerable role in cell-to-cell and lot-to-lot performance variation. Based on a coating loading tolerance of ±0.4 mg/cm 2 and calender tolerance of ±3.0 µm, the resulting theoretical range of physical properties was investigated. For a target positive electrode porosity of 30%, the resulting porosity can range from 19.6% to 38.6%. To account for this variation during the manufacturing process, as much as 41% excess or as little as 59% of the target electrolyte quantity should be added to cells to match the positive electrode void volume. Similar results are reported for a negative electrode of 40% target porosity, where a range from 30.8% to 48.0% porosity is possible. For the negative electrode as little as 72% up to 28% excess electrolyte should be added to fill the internal void space. Although the results are specific to each electrode composition, density, chemistry, and loading the presented process highlight the possible variability of the produced parts. These results are further magnified as cell design moves toward higher power applications with thinner electrode coatings.

A Comparison of Lithium-Ion Cell Performance across Three Different Cell Formats

“…It is much easier to achieve long cycle life in a coin cell using thick lithium metal foils, low coat weight cathodes, and a significant excess of electrolyte. It can be difficult to make direct like for like comparisons of electrolyte quantity across cell formats because there is much more void space or dead volume (proportionately) in a coin cell than a stacked pouch cell [12,13].…”

Calendering of Li(Ni0.33Mn0.33Co0.33)O2‐Based Cathodes: Analyzing the Link Between Process Parameters and Electrode Properties by Advanced Statistics

“…Therefore, when optimizing the manufacturing procedure, special care must be taken when calendering as if high applied pressures are needed, then we would risk to increase the electrode properties deviations. This is known to have a huge impact on battery durability and rejection rate [7,34,35] . The electrode conductivity is mainly controlled by the temperature, indicating that for having a good conductive particle inter‐connectivity (percolation) we must rely on PVdF thermoplasticity.…”

“…This is known to have a huge impact on battery durability and rejection rate. [7,34,35] The electrode conductivity is mainly controlled by the temperature, indicating that for having a good conductive particle inter-connectivity (percolation) we must rely on PVdF thermoplasticity. In terms of electrode formulation, it is known that the electronic conductivity sensitivity towards the calendering parameters is lower when higher amounts of CB/PVdF are used.…”

Lithium-Ion Batteries: Latest Advances and Prospects

“…In response to this call, twelve research papers [19][20][21][22][23][24][25][26][27][28][29][30] and one case report [31] were thoroughly peer-reviewed and published. The published research papers covered advances in several fronts of the technology, including detailed fundamental studies of the electrochemical cell and investigations to better improve parameters related to battery packs.…”

“…The effect of cell manufacturing parameters was also investigated on the performance of the produced LIBs. For example, a theoretical framework was developed to highlight the considerable impact of electrode porosity, electrode internal void volume, cell capacity, and capacity ratio that result from electrode coating and calendering tolerance (as the manufacturing parameters) on the cell-to-cell and lot-to-lot performance variation [26]. In another study published in this Special Issue, the impact of manufacturing parameters in laser cutting, which is a promising technology for the singulation of conventional and advanced electrodes for LIBs, was investigated [27].…”