Lithium has been extensively expected as one of the most ideal anode materials of the next generation lithium-based batteries such as a lithium-air battery (LAB), because of its higher theoretical specific capacity (3860 mA h g^-1) and its most negative redox potential (-3.04 V vs. SHE). During charging, however, it is well known that the dendrite, which further leads to poor performance and short circuit, forms on the lithium anode surface. In addition, solid electrolyte interphase (SEI), which is generated by decomposition of electrolytes and/or solvents, also accumulates on the anode surface during the anode reaction. An ideal SEI layer is expected to be higher and lower conductive for lithium ion and electron, respectively, and it is flexible and has a relatively uniform flat surface with an appropriate thickness, in order to avoid dendrite formation [1]. Thus, we have been trying to construct the “ideal SEI” on the electrode surface [2].

During the electrochemical reaction, on the other hand, electrochemical quartz crystal microbalance (EQCM) technique gives us information not only of mass change on the electrode surface but also resonance resistance change, which shows surface area change of the electrode [3,4] and/or density and viscosity change at the electrode/electrolyte solution interface [5,6]. Moreover, this technique provides us the viscoelasticity of the formed layers on the electrode by the admittance analysis. Using this technique, we found that the native-SEI, which is prepared by the pre-electrochemical treatment of Cu EQCM electrode, strongly effects on the lithium electrodeposition/dissolution processes.

Acknowledgements: This work was totally supported by the Advanced Low Carbon Technology Research and Development Program (ALCA), specially promoted research for innovative next generation batteries (SPRING) from the Japan Science and Technology (JST).

References:

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