Manganese dioxide is a naturally abundant material that is of interest for a wide variety of applications including catalysis, electronics and sensing. In lithium-ion batteries, Mn(IV) can be reduced to Mn(III) by intercalating lithium ions to produce LixMnO2. This intercalation mechanism is favored by the porous structure of MnO2. However, if the MnO2 is too bulky for Li diffusion, the capacity and power delivered by the battery will be reduced. Therefore, there has been considerable interest in developing an efficient method for the synthesis of MnO2 microparticles to decrease the diffusion distances for the transport of lithium ions in batteries. We have previously developed a bipolar electrodeposition method where a voltage was applied across a gold-microtube membrane to oxidize Mn2+ and form MnO2 microparticles at one end of the gold microtubes.1 In this method, the membrane was placed between a solution of sodium sulfate and a solution of sodium sulfate and manganese(II) acetate. In an attempt to lower the voltage applied across the membrane, we replaced the solution of sodium sulfate with a solution of iron(III) chloride. The formation of MnO2 then became spontaneous and occurred without voltage application. MnO2 microparticles were not observed when using a membrane without gold microtubes or when the solutions of manganese acetate and iron chloride were mixed. In this poster presentation, we will present the mechanism of the formation of MnO2 microparticles with iron chloride. We will also show X-ray photoelectron spectroscopy, electron microscopy and electrochemical characterizations of these microparticles.

Gold microtubes to electrolessly synthesize manganese dioxide particles

2019 Spring National Meeting

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