Direct comparison of 2,5-di-tert-butyl-1,4-dimethoybenzene and 4-tert-butyl-1,2-dimethoxybenzene as redox shuttles in LiFePO4-based Li-ion cells

2,5-di-tert-butyl-1,4-dimethoxybenzene (DDB) and 4-tert-butyl-1,2-dimethoxybenzene (TDB) have recently been proposed by different research groups as effective redox shuttles for overcharge protection of LiFePO4-based Li-ion cells. Different test methods used in the published accounts make direct comparison of the merits of DDB and TDB difficult. Here DDB and TDB are tested under the same conditions in Li/LiFePO4, graphite/LiFePO4 and Li4/3Ti5/3O4/LiFePO4 coin-type cells under conditions that approximate those found in practical cells. The results confirm that DDB can support over 200 shuttle-protected overcharge cycles each of 100% cell capacity for all three cell types while TDB can only support between 3 and 15 overcharge cycles. This highlights the importance of testing redox shuttles under conditions that mimic those found in commercial cells.