4) Measuring tool
AFLMBs are appropriate for measuring the reversibility of Li. In the case of LMBs, the cycle stability is often exaggerated by thick Li metal, hiding the degradation of active Li until the depletion of the Li reservoir.[66,67] Therefore, LMBs are not suitable systems for measuring the true reversibility of Li. For AFLMBs, however, the CEs directly present the consumption of Li in every cycle because the inactivated Li is not compensated. Therefore, an anode-free configuration was used to determine the degree of reversibility of Li.[57,66]