Electrochemical behavior of graphite anode at elevated temperatures in organic carbonate solutions

摘要

A combination of three major electroanalytical techniques (slow-scan rate cyclic voltammetry (SSCV), potentiostatic intermittent titration (PITT) and electrochemical impedance spectroscopy (EIS)) was applied for comprehensive analysis of temperature dependence of the most important equilibrium and kinetic parameters related to the Li-insertion process. These parameters include the differential intercalation capacity. C_(int) and the chemical diffusion coefficient, D_(chem). We have analyzed the complicated, ambivalent influence of the temperature on the shape of the cyclic voltammety curves, probing the rate of separate steps of the intercalation process close to equilibrium. Good agreement had been found between the SSCV data measured over a wide range of temperatures, and the classical staging phase diagram of Li_xC_6 (this diagram is presented as a plot of the absolute temperature, T versus intercalation level, x).