Utilizing Half-Cell Measurements to Quantify Electrode Specific Degradation in Lithium-ion Batteries

As the world pushes towards a renewable energy economy, lithium-ion batteries continue to play a critical role in this transition as
an energy storage technology. To accelerate this transition, a deep understanding of battery degradation is necessary to engineer their safety, lifetimes, and performance. In a full cell measurement, degradation at the cathode and anode is convoluted. Methods such as differential voltage fitting (DVF) have been proposed to separate contributions of the total degradation to degradation at individual electrodes. However, these methods need experimental justification to be trusted in informing battery design. This work tackles this issue by dismantling full cells at various states of health (SOH), and reconstructing them in half cells to separately quantify anode and cathode degradation. The procedure developed in this thesis is able to produce reliable and consistent half-cell voltage curves for the anode and cathode that demonstrate the loss of electrode capacity at different SOH. This procedure is demonstrated on 3 full cells at different SOHs, and lays the groundwork for a larger experimental campaign to rigorously test the effects of full cell degradation on individual electrodes.