PI: Zhu, Yu Institution: University of Akron
Lithium-air batteries are promising high-density energy storage systems. The theoretical energy density of lithium-air batteries is comparable with that of gasoline. However, the current lithium-air battery systems suffer from slow and irreversible electrochemical reactions on the cathode and in the electrolyte solution. A fundamental understanding of the reactions taking place in these systems is essential for designing better electrodes and electrolytes that improve energy storage capacity and the number of cycles before battery replacement. The experimental investigations seek to monitor in real time chemical species on the cathode of lithium-air batteries to provide a better understanding of the chemical reaction mechanisms that can lead to improved battery designs.
The proposal aims at exploring the reactions taking place on the cathode of lithium-air batteries using in-situ Raman spectroscopy. The use of polymer templates to fabricate well- organized bi-continuous electrodes made of pristine chemical vapor deposited graphene, gold, or transition metal interstitial compounds is proposed. To enhance the Raman signal, the bi-continuous electrodes will be modified by the adsorption of uniform and regularly assembled gold nanoparticles using either controlled evaporation or template masking. The modified electrodes may allow the detection of trace intermediate compounds by surface-enhanced Raman spectroscopy (SERS). In order to detect the intermediates and products formed in the electrolyte solution, a SERS-active insulating membrane with similar structure as the electrode will be applied to the assembled lithium-air battery. A suite of characterization tools (including Raman, FTIR, TEM, XPS, and XRD) will enable investigation of the materials on the air-cathode and electrolyte solution. Of particular interest are intermediate compounds formed during the charging and discharging processes that will enable addressing fundamental material challenges associated with electrolyte/electrode stability. The studies may provide an improved understanding of lithium-air battery cathode reaction mechanisms and may lead to engineering solutions for high performance, reversible lithium-air batteries. In addition to the training of graduate and undergraduate students, outreach efforts are proposed that will include a Science Olympiad weekend for students in grades 4-6 and activities through the ACS SEED program targeting economically disadvantaged high school students in the Akron, OH, area.
