Meaning
Chemical breakdown of the liquid or solid medium that transports ions between the electrodes. This process occurs through oxidation at the cathode or reduction at the anode, leading to the formation of gases and resistive solids. Managing electrolyte degradation is essential for maintaining the power density and safety of the battery over its operating life.
Gas Generation
Solvents decompose into volatile compounds like carbon dioxide and ethylene when exposed to high voltages. Pressure builds. In pouch cells, this swelling often leads to mechanical misalignment and uneven pressure on the electrodes.
Layer Formation
Solid products from the breakdown settle on the electrode surfaces to form the solid electrolyte interphase and the cathode electrolyte interphase. While an initial layer is necessary to protect the electrode, continuous growth consumes active lithium and increases the internal resistance. Impedance rises.
The depletion of the solvent also leaves the remaining electrolyte more viscous, further slowing the movement of charge. Over time, the chemical balance of the mixture shifts, making the cell more susceptible to thermal instability.
Contaminant Influence
Trace amounts of water or hydrofluoric acid act as catalysts that speed up the decomposition of the salts. Pure manufacturing environments and moisture-proof seals are the primary defenses against this accelerated wear.
