Degradation mechanism of LiMn₂O₄ cathode at high charge cut-off voltages

Abstract

Degradation mechanism of LiMn 2 O 4 cathode at high cut-off voltage of 4.8V has been investigated. Electrochemical tests of the cathode show that the rapid capacity loss due to the oxidation of electrolyte and the generation of oxygen species under high voltage operation leads to the increase of electrode resistance. In addition, a thick layer is found on the cathode surface from scanning electron microscope. The thickness of the layer increases with the increment of charge potentials.

New Insight into Effects of Higher Upper Cutoff Voltage on the Cycling Performance of Graphite‐SiOx/Li‐rich Layered Oxide Pouch‐Type Batteries

“…This is an unanticipated result that is different from the previous studies. [17,21,25,26] Zheng believed that the higher the charging cutoff voltage, the worse the cycling performance. [25] Manthiram found a sharp decrease in capacity retention as the UCV of NCM811/graphite full battery increased from 4.4 to 4.6 V. [26] To further analyze this phenomenon, the difference in Coulombic efficiency should be noticed.…”

“…[17,21,25,26] Zheng believed that the higher the charging cutoff voltage, the worse the cycling performance. [25] Manthiram found a sharp decrease in capacity retention as the UCV of NCM811/graphite full battery increased from 4.4 to 4.6 V. [26] To further analyze this phenomenon, the difference in Coulombic efficiency should be noticed. As shown in Figure 1c, in the first 50 cycles, the Coulombic efficiency of the battery at UCV of 4.4 V is higher than that of the battery at UCV of 4.6 V. After the 50th cycle, the battery using UCV of 4.6 V shows higher Coulombic efficiency, while that is getting lower for the battery at UCV of 4.4 V. The difference between the two is more pronounced after 200 cycles.…”