Sr-doped LaMnO3 (LSM)/MnO2 composites show different electrochemical performance and thus indicate that LSM has a positive effect on the capacitance of MnO2 electrode. A typical LSM(10 wt%)/MnO2 electrode presents a higher capacitance of 287.8 F g(-1) in 1.0 M Na2SO4 aqueous solution, comparing to the pristine MnO2 electrode, 251.7 F g(-1). More interesting, LSM can evidently improve the capacitance of MnO2 electrode under the high rate discharging condition. Compared with the pristine MnO2, LSM(10 wt%)/MnO2 shows excellent capacitance improvement of 11% at low scan rate of 2 mV s(-1), 33% at intermediate scan rate of 50 mV s(-1) and 47.1% at a high scan rate of 200 mV s(-1), respectively. The higher the discharge rate is, the better capacitance improvement can be obtained. Moreover, LSM/MnO2 composite electrode also exhibits excellent cycle performance even after 1000 cycles. These characteristics suggest that LSM/MnO2 composites are promising electrode materials for supercapacitor with high performance.
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