Adsorption mechanisms of lithium oxides (LixO2) on N-doped graphene: a density functional theory study with implications for lithium–air batteries
Adsorption mechanisms of lithium oxides (LixO2) on N-doped graphene: a density functional theory study with implications for lithium–air batteries
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DOI：
10.1007/s00214-016-1805-0
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发表时间：
2016-02
影响因子：
1.7
通讯作者：
Ji Hye Lee;S. Kang;I. Kim;Soonchul Kwon;Inwon Lee;Seung Geol Lee
中科院分区：
文献类型：
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作者：
Ji Hye Lee;S. Kang;I. Kim;Soonchul Kwon;Inwon Lee;Seung Geol Lee
利用密度泛函理论(DFT)研究了锂空气电池氧还原反应过程中锂氧化物(LixO2)在掺氮石墨烯上的吸附机理。我们系统地提出了两种可能的ORR途径，并考察了每个体系中不同的吸附构型，包括O2和LiORR反应物以及LiO2和Li2O2ORR产物。由于富电子的N掺杂石墨烯与给电子的Li原子之间的排斥力，以及N掺杂石墨烯对电负性O2的吸引，计算结果表明，N原子的掺杂增强了O2的吸附，但减弱了Li的吸附。然而，由于锂在N掺杂石墨烯(−1.001至−0.503 eV)上的吸附仍强于O2(−0.280至−0.215 eV)的吸附，因此Li应首先与N掺杂石墨烯结合。此外，计算了N掺杂石墨烯对LiO2(−0.588 eV)的结合强度比原始石墨烯(−0.450 eV)更强。此外，计算了在N掺杂石墨烯上产生最稳定吸附的Li2O2构型，得到的吸附能为−0.642 eV，比原始石墨烯的−0.630 eV更有利。总体而言，掺杂N的石墨烯可以增强锂氧化物(LixO2)的吸附，并将电荷转移增加到相当大的水平。
We utilized density functional theory (DFT) study to understand the adsorption mechanism of lithium oxides (LixO2) onto N-doped graphene during oxygen reduction reaction (ORR) for lithium–air batteries. We systematically proposed two possible ORR pathways and examined various adsorption configurations in each system, including for the O2and Li ORR reactants and the LiO2and Li2O2ORR products. The doping of the N atom into graphene was calculated to enhance the adsorption of O2, but to attenuate the adsorption of Li, because of the repulsion between the electron-rich N-doped graphene and the electron-donating Li atom, and the attraction of this N-doped graphene for electronegative O2. Nevertheless, since the adsorption of Li onto N-doped graphene (−1.001 to −0.503 eV) was still stronger than the adsorption of O2(−0.280 to −0.215 eV), Li should bind N-doped graphene first. Moreover, N-doped graphene was calculated to bind LiO2(−0.588 eV) more strongly than was pristine graphene (−0.450 eV). Additionally, the Li2O2configuration that yielded the most stable adsorption on N-doped graphene was calculated to yield an adsorption energy of −0.642 eV, which is more favorable than that for pristine graphene (−0.630 eV). Overall, N-doped graphene was found to strengthen the adsorption of lithium oxides (LixO2) and increase charge transfer to substantial levels.