| With the development of new clean energy sources, electrochemical capacitors?ECs? as an important energy storage device have many potential application prospects. Therefore ECs attract much attention in energy-storage field used in hybrid vehicles, but the low energy density of electrode materials can't meet the application for many respects. A new material manganese carbonate ?MnC03? has just been found the characteristics of energy storage. In order to expand the field of electrochemical capacitor electrode material, We study the new energy storage material manganese carbonate in two aspects.One of them targets on the charge storage mechanism, the charge storage mechanism of MnCO3/Carbon black ?CB?/PTFE electrode in 1M Na2SO4 electrolyte was investigated by in-situ Raman spectroscopy and X-ray photoelectron spectroscopy. The Raman spectra reveal that MnCO3 is soon intercalated by Na+ and a small portion of it converts to Mn?OH?2, MnOOH and Mn2O3 as soon as the electrode meets Na2SO4 aqueous electrolyte. CB helps the intercalation and, as a result, a composite electrode other than MnCO3 itself takes part in a practical charging/discharging cycle. The concentration gradient of Na+ contributes to a capacitive pattern of adsorption pseudo-capacitor and the electro-redox pair of Mn???/Mn??? accounts for the dominant pseudo-capacitive performances.The other aspect aims at improving the specific capacitance of electrode material.In Order to improve the characterization of MnCO3, a three-dimensional composite of MnCO3 and carbon black ?CB? are built via a quite simple liquid phase precipitation method at room temperature. MnCO3 like lotus is mixed with flocculated carbon black with diameter 700nm which identified by SEM. We find many negative groups?carboxyl and quinone? on the purified CBs' surface by FT-IR and XPS, which make CB difficult to reunite in the water. The cyclic voltammetry of the MnCO3/CB nano-composite show better electrochemical performance than pure MnCO3. |
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