Gas formation during the initial charge and discharge (formation cycles) of lithium-ion batteries is often overlooked and can indicate the future performance of a battery. As the battery undergoes formation cycling, the electrolyte reacts with electrode materials and current collector surfaces to build protective layers known as the Solid Electrolyte Interphase (SEI) and the Cathode Electrolyte Interphase (CEI). These layers are essential for long cycle life and thermal stability, yet their creation generates mixtures of hydrogen and volatile organic gases that have to be removed and treated during manufacturing.
About Gas Formation
During the first few cycles of a lithium-ion cell, the electrolyte decomposes at the electrode surfaces to form passivation layers. On the anode side, the reduction of carbonate solvents such as ethylene carbonate produces compounds including lithium ethylene dicarbonate and lithium carbonate. On the cathode side, especially with high-nickel layered oxides, oxidation of the electrolyte yields carbon dioxide and carbon monoxide. Trace moisture in the cell exacerbates the problem by reacting with the lithium hexafluorophosphate salt into hydrogen fluoride (HF) and phosphoryl fluoride. HF then attacks surface films on electrodes, releasing additional gas such as hydrogen and carbon dioxide. The combined gas mixture must be removed after formation through degassing steps, adding time and cost to cell manufacturing. The objective in battery cell design is to limit these side reactions while still forming robust interphase layers that protect electrodes.
How Addionics 3D Current Collectors Reduce Gassing
Reducing gas generation during battery formation requires addressing the root cause of side reactions within the cell. Addionics 3D porous current collectors offer a multifaceted solution by improving the physical and electrochemical environment at the electrode interface.
Improved Solvent Drying
The porous structure of the Addionics current collector significantly enhances drying efficiency by allowing solvent to evaporate more quickly and uniformly, thereby reducing the amount of residual moisture. Lower water content in the electrode is crucial because it minimizes undesirable electrolyte-water reactions, which can produce HF and hydrogen gas. By limiting these reactions, the design decreases hydrogen generation during cell formation, which reduces the amount of gas that has to be removed and improves the lifetime of the batteries.
More Efficient Interphase Formation
The 3D architecture of the porous current collector promotes superior electrolyte wetting, ensuring that the electrolyte penetrates and coats the active material uniformly. This uniform coverage supports the growth of a consistent, high-quality SEI layer. A robust and homogeneous SEI reduces parasitic side reactions, which in turn lowers gas evolution and extends the cycle life of the cell. In contrast, inadequate wetting in less porous structures can lead to patchy SEI formation, leaving inactive or underutilized surface areas that compromise both performance and longevity.
Enhanced Gas Transport and Release
Addionics 3D Current Collectors also facilitate more efficient gas diffusion out of the electrode structure during formation. This rapid and uniform gas release prevents localized pressure buildup within the electrode, which could otherwise crack the SEI layer. SEI damage exposes fresh electrode material to the electrolyte, triggering additional decomposition reactions and generating even more gas. By enabling smooth gas transport, the porous structure helps preserve SEI integrity, contributing to stable performance and reduced degradation over time.
Quantified Improvements in Gas Reduction
When used in one-ampere-hour pouch cells, by replacing one traditional current collector with Addionics 3D Current Collectors, the amount of gas generated is reduced by around 10% during formation with graphite-nickel-manganese-cobalt cathodes. When both the anode and cathode foils are replaced with 3D porous copper and aluminum current collectors, the overall gas reduction reaches 19%. In cells with lithium-iron-phosphate chemistries, the porous current collectors caused a 23% decrease in gas volume removed after formation cycling. These results demonstrate that the benefits of Addionics technology extend across multiple electrode chemistries and processing routes.
Enabling Cleaner Formation and Better Performance with Addionics
Gas formation during lithium-ion battery formation remains an overlooked process for high-yield manufacturing and an indicator for long cycle life. Addionics 3D Current Collectors address this challenge through a combination of improved solvent drying, more uniform electrolyte wetting, and enhanced gas transport. The effect is a significant reduction in hydrogen and volatile organic compound generation while improving the protective SEI and CEI. As a drop-in solution compatible with all existing and emerging chemistries, Addionics’ technology offers battery manufacturers a path to higher throughput, lower manufacturing costs, and longer cycle life cells. By integrating porous current collectors into production lines, manufacturers can build the next generation of batteries with confidence in both performance and reliability.
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