Electrolytic manganese oxides

OMS and OL materials may also find applications in areas presently employing conventional manganese oxide materials such as electrolytic manganese oxide (deposition at electrode surfaces), dry cell batteries, production of ferrites, as components of oxidation catalysts, and for crosslinking of rubber. 104 potential applications in separation science,105 environmental catalysis,106 and biological systems 107 may also be possible. Other possibilities include use as sensors,100 as supports for metal clusters, 109 and in disposal of radioactive metal ions.H0... 

Electrolytic Manganese Dioxide. The anodic oxidation of an Mn(II) salt to manganese dioxide dates back to 1830, but the usefuhiess of electrolyticaHy prepared manganese dioxide for battery purposes was not recognized until 1918 (69). Initial use of electrolytic manganese dioxide (EAfD) for battery use was ia Japan (70) where usage continues. 

Rather than natural ores as in Leclanche batteries, electrolytic manganese dioxide (EMD), which is produced by anodic oxidation of Mn ions at graphite electrodes in solutions of manganese salts, is used as the active material for the positive... 

The performance of manganese oxide in a real two-electrode capacitor is limited by the irreversible reaction Mn(IV) to Mn(II) taking place at the negative electrode, which potential depends on the electrolyte pH. 

Jeong YU, Manthiram A. Nanocrystalline manganese oxides for electrochemical capacitors with neutral electrolytes. J. Electrochem. Soc. 2002 149(11) A1419-A1422. 

Hong MS, Lee SH, Kim SW. Use of KC1 aqueous electrolyte for 2 V manganese oxide/activated carbon hybrid capacitor. Electrochemical and solid state letters 2002 5(10) A227-A230. 

Preliminary electrochemical tests of materials obtained have been performed in two types of cells. Primary discharge measurements have been executed in standard 2325 coin-type cells (23 mm diameter and 2.5 mm height) with an electrolyte based on propylene carbonate - dimethoxyethane solution of LiC104. Cathode materials have been prepared from thermally treated amorphous manganese oxide in question (0.70 0.02g, 85wt%.) mixed with a conductive additive (10 % wt.) and a binder (5wt%). Lithium anodes of 0.45 mm thickness have been of slightly excess mass if compared to the stoichiometric amount, so as to ensure maximal possible capacity of a cell and full consumption of the cathode material. 

Promising results have also been obtained in cycling ability studies performed in model coin-type cells with this same amorphous cathode material. Moreover, it has been found that either thermally treated or even initial amorphous manganese oxide exhibit satisfactory results. Cyclic voltammetric studies have been carried out with the LP-30 electrolyte (Merck). Cathode materials have been prepared from amorphous manganese oxide in question (80wt%) mixed with a conductive additive (10wt%) and a... 

Figure 1. Discharge curves for 2325 coin cells with lithium metal anodes and electrolytic (crystalline) vs amorphous manganese oxide-based cathodes.

CNTs were also demonstrated to be a perfect support for cheap transition metal oxides of poor electrical conductivity, such as amorphous manganese oxide (a-Mn02 H20) [5,96], The pseudocapacitance properties of hydrous oxides are attributed to the redox exchange of protons and/or cations with the electrolyte as in Equation 8.13 for a-Mn02 H20 [97] ... 

FIGURE 8.36 Cyclic voltammograms on an optimized asymmetric manganese oxide/activated carbon capacitor in 2mol L 1 KN03 electrolyte. (Adapted from Khomenko, V., et al.,./. Power Sources, 153, 183, 2006.)... 

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