context: The vanadium loss of the cathode is measured using inductive coupled plasma optical emission spectroscopy (ICP OES) after 7, 20 and 40 cycles in the discharged state as it is difficult to accurately quantify the small amount of dissolved vanadium after the first cycle. It can be seen from Fig. 9 that a considerable amount of V is lost from the cathode. The extent of vanadium dissolution is roughly proportional to the upper potential limit used in the cycling, which indicates a correlation between the V loss and the anionic redox activity. The vanadium dissolution allows the V4+ ions and partially oxidized oxygen ions (e.g., O− ions, peroxides and superoxides) to remain in the structure upon the reinsertion of Li+ based on the charge neutrality. The formation of anionic redox species and its reversibility are closely linked to the vanadium dissolution, although their causalities remain unclear (i.e., whether the vanadium dissolution leads to the formation of anionic redox species and reduce its reversibility, or vice versa). We note that a lack of causality is also possible as they may occur simultaneously to stabilize each other due to their opposite contribution to the net charge.