Evaluation of components of Li-O2 battery positive electrode capacitance by a voltammetric method

In the present work, the capacitance of a positive electrode based on CNTOH is addressed. The variations in its double-layer (C-DL) and pseudocapacitance (C-PC) components were evaluated using cyclic voltammetry during testing lithium-oxygen battery (LOB). A decrease in C-DL during the discharge process is established, equal to 64 %, 26 %, and 12 % of the initial value at current densities of 100, 200, and 500 mA g(C)(-1), respectively. The behavior of the C-DL values and maximum discharge capacity under various current densities indicates that the oxygen concentration polarization affects the discharge characteristics of LOB. This influence exceeds the effect of blocking the positive electrode surface by the products formed in the cathode process. During LOB cycling, a decrease in the maximum discharge capacity correlates with a reduction in C-DL, possibly, due to corrosion of the carbon material. An increase in C-PC with prolonged cycling is explained by the accumulation of side products formed during discharging and charging.

Automated summary

In this study, the variations in the capacitance of a positive electrode based on CNTOH were evaluated using cyclic voltammetry. It was found that the discharge characteristics of LOB were significantly influenced by oxygen concentration polarization. Additionally, the decrease in maximum discharge capacity was correlated with the reduction in C-DL, while the increase in C-PC was attributed to the accumulation of side products formed during discharging and charging.