Atomic layer deposited TiO2 on a nitrogen-doped graphene/sulfur electrode for high performance lithium–sulfur batteries
Atomic layer deposited TiO2 on a nitrogen-doped graphene/sulfur electrode for high performance lithium–sulfur batteries
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DOI：
10.1039/c5ee03902a
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发表时间：
2016-04
影响因子：
32.5
通讯作者：
Mingpeng Yu;Junsheng Ma;Hongquan Song;Aiji Wang;Fuyang Tian;Yinshu Wang;H. Qiu;Rongming Wang
中科院分区：
文献类型：
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作者：
Mingpeng Yu;Junsheng Ma;Hongquan Song;Aiji Wang;Fuyang Tian;Yinshu Wang;H. Qiu;Rongming Wang
氮掺杂的石墨烯（NG）已经被制造并用作硫浸渍的碳基质以构造锂-硫（Li-S）电池的阴极。在电极上进一步沉积TiO 2的原子层，并通过将沉积循环数调节为0、5、20和40来控制厚度。结果表明，与裸电极相比，所有表面改性电极都表现出高容量、良好的倍率性能和增强的循环性能。具体地，该电极含有59%（按重量计，wt%）的硫，并且通过添加20次循环的TiO 2，其在活性硫利用率方面表现出上级提高（放电容量：在0.1C下为1374 mA h g-1）。它还提供了初始放电容量高达1069.5 mA h g−1和918.3 mA h g−1，在1C下500次循环后，平均库仑效率约为99.7%。此外，添加20次循环的TiO 2，从0.1C到4C的容量保持率从42%增加到61%。电化学性能的改善可归因于TiO 2对多硫化物的原位吸附保留以及电荷转移增强。理论计算表明，二氧化钛表现出很强的结合能的多硫化锂物种。这些结果表明，TiO 2改性NG具有用作高性能Li-S电池阴极的潜力。
Nitrogen-doped graphene (NG) has been fabricated and used as a carbon matrix for sulfur impregnation to construct cathodes for lithium–sulfur (Li–S) batteries. Atomic layers of TiO2 were further deposited on the electrode and the thickness was controlled by adjusting the number of deposition cycles to 0, 5, 20 and 40. The results showed that all the surface modified electrodes demonstrate high capacity, good rate capability, and enhanced cyclability compared to the bare electrode. Specifically, the electrode contained 59% (by weight, wt%) sulfur and with the addition of 20 cycle-TiO2 it demonstrated a superior boost in the active sulfur utilization (discharge capacity: 1374 mA h g−1 at 0.1C). It also delivered initial discharge capacity up to 1069.5 mA h g−1 and 918.3 mA h g−1 after 500 cycles at 1C with an average coulombic efficiency of about 99.7%. Moreover, the capacity retention increased from 42% to 61% from 0.1C to 4C with the addition of 20 cycle-TiO2. The improved electrochemical performance could be attributed to the on-site TiO2 absorption for polysulfide retention as well as the charge transfer enhancement. Theoretical calculations revealed that TiO2 exhibits a strong binding energy for lithium polysulfide species. These results suggest that the TiO2 modified NG has potential to be used as a cathode for high-performance Li–S batteries.