A REVIEW OF METAL OXIDE COMPOSITE ELECTRODE MATERIALS FOR ELECTROCHEMICAL CAPACITORS

With the emerging technology in the 21st century, which requires higher electrochemical performances, metal oxide composite electrodes in particular or er complementary properties of individual materials via the incorporation of both physical and chemical charge storage mechanism together in a single electrode. Numerous works reviewed herein have identified a wide variety of attractive metal oxide-based composite electrode material for symmetric and asymmetric electrochemical capacitors. The focus of the review is the detailed literature data and discussion regarding the electrochemical performance of various metal oxide composite electrodes fabricated from different configurations including binary and ternary composites. Additionally, projection of future development in hybrid capacitor coupling lithium metal oxides and carbonaceous materials are found to obtain significantly higher energy storage than currently available commercial electrochemical capacitors. This review describes the novel concept of lithium metal oxide electrode materials which are of value to researchers in developing high-energy and enhanced-cyclability electrochemical capacitors comparable to Li-ion batteries. In order to fully exploit the potential of metal oxide composite electrode materials, developing low cost, environment-friendly nanocomposite electrodes is certainly a research direction that should be extensively investigated in the future.