Development of Non-Deteriorating Lithium-Sulfur Battery

Abstract

To resolve energy issues, the demand of large-scaled capacity storage batteries are increasing. Therefore, the realization of lithium-sulfur (Li-S) battery, which is one candidate of the next-generation high-performance innovative battery systems, is strongly desired. In general, lithium metal is used as the negative electrode for Li-S batteries. On the other hand, elemental sulfur (S8) is also used as the positive electrode, and it has high theoretical reversible capacity of 1,672 mAhg-1. However, effect of Li metal negative electrode is unclear due to their chemical properties with charge/discharge process. In this study, we applied Li-doped negative electrode for suppressing the Li-dendrite formation. Therefore, we obtained Li4Ti5O12 (LTO) electrode as stable negative electrode, which is strain-free intercalation material, and high reversible characteristics of battery system are expected.To applying LTO for Li-S batteries, electrochemical doping of Li into LTO is required owing to their lack of carrier ion into LTO. Therefore, at first [Li| electrolyte |LTO] cells were assembled by using disassemble cell, which can be easily taken out cell materials without short circuit into inert atmosphere (e.g., glove box). After takeoff of Li-doping LTO (Li-LTO), lithium (Li-doped) -sulfur battery was fabricated by using SPAN as sulfur positive electrode ([Li-LTO|1M-LiFSI EC/DEC=3/7|SPAN] cell). (SPAN:developed non-degraded S positive electrode). Charge / discharge performance of prepared cells were evaluated.Fig. 1 (a) and (b) shows the charge and discharge profiles and the cycle number dependences of coulombic efficiency for prepared cell at 303K. Although operating voltage and capacity are relatively low, charge and discharge over 2000 cycles were observed. Therefore, this cell has suitable constitution in battery materials. Within 200 cycles, high coulombic efficiencies (about 99.9%) were always observed. Therefore, it suggests the possibility of realizing a non-degraded battery, which has high reversible characteristics by using Li-LTO electrode and SPAN electrode. Figure 1