Figure 7

Nyquist plots of (a) LiMg_0.08Mn_1.92O₄ and (b) LiNi_0.03Mg_0.08Mn_1.89O₄ before cycling and after 1000 cycles, the insets in a and b are the equivalent circuit, Nyquist plots of (c) LiMg_0.08Mn_1.92O₄ and (d) LiNi_0.03Mg_0.08Mn_1.89O₄ electrodes at different temperatures, the insets in c and d are the Arrhenius plots of log (i₀/A) vs. 1/T.