Comparative study of Li[Ni1/3Co1/3Mn1/3]O-2 cathode material synthesized via different synthetic routes for asymmetric electrochemical capacitor applications

Abstract

Layered Li[Ni1/3Co1/3Mn1/3]O-2 cathode materials were synthesized by different synthesis routes using carbonate and hydroxide co-precipitation methods. Physical properties of the prepared Li[Ni1/3Co1/3Mn1/3]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[Ni1/3Co1/3Mn1/3]O-2 prepared by the carbonate co-precipitation exhibited higher capacitance and better rate capability with stable cycling retention over 500 cycles than Li[Ni1/3Co1/3Mn1/3]O-2 prepared by the hydroxide co-precipitation. The asymmetric electrochemical capacitor (AEC) cell (AC/Li[Ni1/3Co1/3Mn1/3]O-2) had a voltage slope from 0.2 to 2.2 V and delivered a capacity of 60 F g(-1) 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. (C) 2008 Elsevier B.V. All rights reserved.