1) Low reversibility of Li
The absence of excess Li metal brings not only huge advantages but also
causes rapid capacity decay of AFLMBs within a few cycles. Owing to the
high reactivity of Li metal, active Li is continuously consumed by the
reaction with the electrolytes and the formation of dead
Li.[35,68] Without excess Li metal, CEs are
directly related to the reversibility of the Li stripping/plating
process. The correlation between the average CEs (aCEs) and cycle life
is shown in Table 1.[41] High aCEs (>
99.978 %) are required for AFLMBs to practically compete with
commercial LIBs (> 500 cycles), but this has not yet been
achieved. Even when aCEs are highly improved to 99.8%, the cell only
exhibits 80% capacity retention after only 100 cycles, which is far
below the commercialization. Therefore, even if a high initial energy
density is achieved through AFLMBs, it drops rapidly within several
cycles.