Effects of lithium salt concentration on graphited carbon microbead anodes in the piperidinium-based hybrid electrolytes

Abstract

The variations in LiPF6 concentration lead to the very different electrochemical performances of carbon microbeads anodes in the piperidinium-based hybrid electrolytes. The “two peaks” behaviors of lithium plating observed in cyclic voltammetry tests, and some detailed changes in infrared spectra and nuclear magnetic resonance indicates that the formation of “ionic aggregates” related to lithium ions”. Therefore, the excessive lithium salts in the piperidinium-based hybrid electrolytes, usually cause a significant decrease in Li+ mobility and transfer efficiency. The main behaviors are that, when LiPF6 concentrations increased from 0.2 to 1.2molkg−1, the apparent migration energies (Ea) increase largely from 8.83 to 21.16kJmol−1, while the lithium transference numbers (tLi+) drop markedly from 0.538 to 0.292.