Zhaojun Meng,Ke Wang,Haotian Bai,Lijun Han,Zhiwen Yang,Yanrong Liu
Lithium-mediated nitrogen reduction reaction (Li-NRR) is a promising reaction pathway to realize green ammonia production. However, there is a lack of clear understanding on how solid electrolyte interphase (SEI) membranes affects Li-NRR performance. The effects of different lithium salts on the SEI layer were investigated in this work. Among lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), and lithium trifluoromethanesulfonate (LiOTf), LiOTf showed better ammonia synthesis performance. At 1 bar N 2 and −6 mA cm −2 current density, the faraday efficiency (FE) and ammonia production rate reached 16.94 ± 0.67 % and 3.51 ± 0.14 nmol s −1 cm −2 , respectively. Conversely, the LiBF 4 electrolyte has the lowest NH 3 selectivity and rate under identical operating conditions, which are only 2.41 ± 0.16 % and 0.50 ± 0.03 nmol s −1 cm −2 . Cryo-electron microscopy reveals the influence of SEI nanostructures and chemical properties on the performance of lithium-mediated electrochemical synthesis of ammonia. The results of Cryo-electron microscopy showed that the SEI membranes of LiOTf electrolyte exhibited a reticular structure, which was favorable for N 2 adsorption, while the SEIs of LiClO 4 and LiBF 4 electrolytes had a lamellar and irregular planar structure, respectively. Molecular dynamics (MD) simulations and density functional theory (DFT) results showed that the LiOTf electrolyte can more easily generate a stable SEI membrane on the electrode surface. These findings highlight the importance of SEI structure in enhancing the reaction process, and thus provide valuable suggestions for the development of artificial SEI with specific structure.
Yuan Li,Lei Zhao,Yongtao Tan,Xiangye Li,Rui Wang,Yuanyou Peng,Youzhi Wu,Fen Ran
Dendritic growth, hydrogen evolution reaction, and passivation of zinc anode severely limit the practical use of zinc metal batteries. Developing acidic electrolyte additives is capable of markedly augmenting the stability of zinc anode. However, the adsorption type of acidic additives on zinc anode is still unclear and its mechanism of stabilizing zinc anode needs to be further studied. In this work, the adsorption types of three dicarboxylic acids on zinc anode and action mechanism of stabilizing zinc anode are investigated in depth. The results show that the adsorption type of dicarboxylic acid on zinc anode is chemical adsorption instead of physical adsorption. The dicarboxylic acid reacts with the zinc anode to produce corresponding dicarboxylate and H 2 . The dicarboxylate significantly inhibits the side reactions occurring at the zinc anode. As the number of -OH groups on the dicarboxylic acid backbone increases, the faster the chemical adsorption rate, the better the inhibition of side reactions. However, the loss of zinc anode is also more serious. In addition, the relationship between the SEI structure of Zn anode and the chemical adsorption of organic acids is explored. Compared with malic acid and tartaric acid additives, succinic acid additive has the best effect in stabilizing Zn anode. Zn||Cu asymmetric battery can be stably cycled for upwards of 2, 760 h at 4 mA/cm 2 and 4 mAh/cm 2 . This work provides valuable guidance for elucidating the action mechanism of stabilizing zinc anode with acidic electrolyte additives.
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