비대칭 전극을 이용한 전기화학 커패시터용 양극활물질의 합성 방법에 따른 특성 연구

Abstract

Layered Li[Ni_(1/3)Co_(1/3)Mn_(1/3)]O_(2) cathode materials were synthesized by different synthesis routes using carbonate and hydroxide co-precipitation methods. Physical properties of the prepared Li[Ni_(1/3)Co_(1/3)Mn_(1/3)]O_(2) varied depending on the synthesis method employed. These materials were applied as a positive electrode to an asymmetric electrochemical capacitor with activated carbon as the negative electrode and the electrochemical properties of the capacitor were studied. Li[Ni_(1/3)Co_(1/3)Mn_(1/3)]O_(2) prepared by the carbonate co-precipitation exhibited higher capacitance and better rate capability with stable cycling retention over 500 cycles than Li[Ni_(1/3)Co_(1/3)Mn_(1/3)]O_(2) prepared by the hydroxide co-precipitation. The asymmetric electrochemical capacitor (AEC) cell (AC/Li[Ni_(1/3)Co_(1/3)Mn_(1/3)]O_(2)) had a voltage slope from 0.2 to 2.2 V and delivered a capacity of 60 F/g with a capacity retention of 88.4% during 500 cycles based on the overall active materials weight. The leakage current was largely decreased for the asymmetric electrochemical capacitor and the maintained voltage was 84.4% during 3 days.