Oxygen-vacancy europium-doped MnO2 ultrathin nanosheets used as asymmetric supercapacitors

In term of supercapacitors application, MnO2 has been recognized as a popular pseudocapacitive material on account of its environmental friendliness, cost inexpensive, plentiful abundance and high theoretical capaci-tance. However, its inherently low conductivity and structural instability lead to low specific capacitance and short cycle life, which greatly limit its development. Rare-earth doping can manipulate the size, shape, and crystallographic phase of doped nanomaterials. For the sake of hoisting the supercapacitors performance of MnO2, herein, we synthesized europium-doping MnO2 (Eu5%-MnO2) ultrathin nanosheets (3.4 nm) possessing rich oxygen vacancies via a facile co-precipitation strategy. The specific capacitance of Eu5%-MnO2 at 1 A g-1 is 361.2 F g-1 and remains 100% after 10,000 cycles, outperforming of MnO2 nanosheets (198 F g-1, 82.8%). The reason of enhancing performance may be mainly correlation to the heighten conductivity, boosted surface reactivity and electrochemical active sites. The assembled Eu5%-MnO2//AC device at 1 A g-1 can reach 63.36 F g-1 with high voltage of 3 V and exerts 19.8 Wh kg- 1 of energy density when the power density is 373.2 W kg -1. This synthesis technique is a simple and convenient means for the development of high-performance MnO2-based energy storage electrodes.

Automated summary

Rare-earth doping can enhance the performance of MnO2 supercapacitors. We synthesized Eu5%-MnO2 ultrathin nanosheets with rich oxygen vacancies via a facile co-precipitation strategy. The specific capacitance of Eu5%-MnO2 is 361.2 F g-1, and it remains 100% after 10,000 cycles, outperforming MnO2 nanosheets.