A concentration cell has identical electrodes but different electrolyte concentrations. $E_{standard}$ = 0 (same electrode material). $E_{cell}$ = -$\frac{0.0592}{n}$log$\frac{C_dilute}{C_concentrated}$ = $\frac{0.0592}{n}$log$\frac{C_concentrated}{C_dilute}$. The cell drives toward equalising concentrations: dilute side is the anode (metal dissolves to increase [$M^{n+}$]), concentrated side is the cathode ($M^{n+}$ deposits to decrease [$M^{n+}$]). For Ag|Ag+(0.001M)||Ag+(0.1M)|Ag: E = (0.0592/1)log$\frac{0.1}{0.001}$ = 0.0592 * 2 = 0.1184 V. Concentration cells demonstrate that EMF depends on concentration ratios.