What is the role of electrolyte decomposition in battery degradation?

Electrolyte decomposition plays a significant role in battery degradation by leading to capacity fade, increased internal resistance, and reduced lifespan. The electrolyte is the medium that facilitates the transport of ions between the cathode and anode. Over time, the electrolyte can decompose due to various factors, including high voltage, high temperature, and electrochemical reactions with the electrode materials. The decomposition products can form a solid layer on the electrodes, increasing the internal resistance of the battery and hindering ion transport. This solid layer, often contributing to the Solid Electrolyte Interphase (SEI) layer, can also consume lithium ions, reducing the amount of cyclable lithium and contributing to capacity fade. Electrolyte decomposition can also lead to the formation of gases, which can cause swelling of the battery and increase the risk of safety hazards. The rate of electrolyte decomposition is accelerated by high temperatures, making thermal management critical for mitigating this degradation mechanism. Stabilizing the electrolyte and using additives to inhibit decomposition are common strategies for extending the lifespan of batteries.