Improving the cycling performance of lithium-air batteries using a nitrite salt electrolyte

Shota Azuma; Mitsuki Sano; Itsuki Moro; Fumisato Ozawa; Morihiro Saito; Akihiro Nomura

doi:10.1016/j.electacta.2024.144261

ジャーナル論文 Improving the cycling performance of lithium-air batteries using a nitrite salt electrolyte

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Shota Azuma, Mitsuki Sano, Itsuki Moro, Fumisato Ozawa, Morihiro Saito, Akihiro Nomura. Improving the cycling performance of lithium-air batteries using a nitrite salt electrolyte. ELECTROCHIMICA ACTA. 2024, 489 (), 144261. https://doi.org/10.1016/j.electacta.2024.144261

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(abstract)

Developing high energy density lithium-air batteries (LABs) with sufficient cycle life is challenging due to the oxidative degradation of various battery components during charging. Lithium nitrate (LiNO3) has been commonly used as the electrolyte salt, both to protect the lithium anode and to generate NO2- anions that function as the redox mediator (RM) to reduce the charging voltage. However, this RM effect only minimally improves cycling performance because only a low NO2- concentration is produced. The use of lithium nitrite (LiNO2) as the supporting electrolyte salt could overcome this limitation. In the present study, 1 M solutions of LiNO3 or LiNO2 were prepared in tetraethylene glycol dimethyl ether (TEGDME) or N-methyl-2-pyrrolidone (NMP) as LAB electrolytes. Walden plots of these electrolytes established a higher degree of dissociation in the NMP, which had a greater dielectric constant, thus enhancing ionic conductivity. Electrochemical impedance spctroscopy determined that a LAB cell incorporating the LiNO2/NMP electrolyte exhibited reduced diffusion resistance during discharge-charge cycling as a consequence of the RM effect of NO2- anions. Microscopic observation and pore distribution analysis of cathodes confirmed that the clogging of pores was minimized with the LiNO2/NMP electrolyte. As a result, the LAB cell using this system showed the best performance, more than doubling the cycle life. Based on these data, LiNO2 is considered to be an effective electrolyte salt for use in LABs.

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