Rechargeable Alkaline Manganese Dioxide Research Articles

Preparation of ultrafine Ag3BiO3 and modification mechanism on EMD cathode for rechargeable alkaline manganese dioxide battery

Preparation of ultrafine Ag3BiO3 and modification mechanism on EMD cathode for rechargeable alkaline manganese dioxide battery

Impact of cathode additives on the cycling performance of rechargeable alkaline manganese dioxide–zinc batteries for energy storage applications

The impact of chemical additives [e.g., BaSO4, Sr(OH)2·8H2O, Ca(OH)2, and Bi2O3] on the cycling performance of rechargeable alkaline electrolytic manganese dioxide/Zn batteries has been studied. The additives were used in the cathode electrodes consisting of 5 wt% additive, γ-MnO2 (electrolytic manganese dioxide—EMD—80 wt%) and KS44 graphite (15 wt%) in prismatic-type electrode geometries. Powder X-ray diffraction analysis showed the formation of alkaline earth metal carbonates (BaCO3, SrCO3) when the electrodes come into contact with the highly alkaline (pH 15, 9 M KOH) electrolyte. The presence of dissolved carbonate in the electrolyte leads to a double replacement precipitation reaction leading to the formation of these carbonate species. These additives help with the cycle life of the electrolytic manganese dioxide cathode material. The overall energy efficiency of the cells is about 75%. Rate capability studies and equilibrium potential measurements by galvanostatic intermittent titration technique analysis indicate that ohmic polarization plays a significant role in the energy loss and should be improved for high power applications. Rechargeable alkaline batteries with electrolytic manganese dioxide/Zn chemistry provide a low-cost and an environmentally friendly solution for storage of energy. Improvement of this technology would be an important contribution in the area of energy storage applications. The impact of a number of chemical additives (e.g., BaSO4, Sr(OH)2·8H2O, Ca(OH)2 and Bi2O3) on the cycling performance of rechargeable alkaline EMD/Zn batteries has been studied. The additives were used in the cathode electrodes consisting of 5 wt% additive, γ-MnO2 (electrolytic manganese dioxide—EMD—80 wt%) and KS44 graphite (15 wt%) in prismatic-type electrode geometries. Powder X-ray diffraction analysis showed the formation of alkaline earth metal carbonates (BaCO3, SrCO3) when the electrodes come into contact with the highly alkaline (pH 15, 9 M KOH) electrolyte. The presence of dissolved carbonate in the electrolyte leads to a double replacement precipitation reaction leading to the formation of these carbonate species. These additives help with the cycle life of the EMD cathode material. The overall energy efficiency of the cells is about 75%. Rate capability studies and equilibrium potential measurements by galvanostatic intermittent titration technique analysis indicate that ohmic polarization plays a significant role in the energy loss and should be improved for high power applications. Rechargeable alkaline batteries with EMD/Zn chemistry provide a low-cost and an environmentally friendly solution for storage of energy. Improvement of this technology would be an important contribution in the area of energy storage applications.

Influence of the solution pH on the nanostructural, and electrochemical performance of electrolytic manganese dioxide

In this paper, during electrodeposition of electrolytic manganese dioxide (EMD) by anodic deposition from MnSO 4 solution, the changing of pH is studied. The pH shows a decreasing trend. Two samples are electrodeposited at fixed pH (2 and 5) and their physico-chemical properties are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), the Barrett–Joyner–Halenda (BJH) method, and rechargeable alkaline manganese dioxide (RAM) battery tests. The results have confirmed that the pH of the solution has remarkable effects on the nanostructure, crystal structure, porosity, and the electrochemical performances of the EMD. Whereas the electrodeposition at pH 2 creates irregular multi-branched morphology with meso/microporosity, a large number of regular nanospheres with microporosity are obtained at pH 5. The battery tests study has revealed that α/γ-MnO 2 electrodeposited at pH 2 exhibits good electrochemical performances, and the α-MnO 2 displays very stable cycling behavior.

Development of flat plate rechargeable alkaline manganese dioxide–zinc cells

This paper was focused on the development of prototypes for flat plate RAM™ (rechargeable alkaline manganese dioxide) cells. In contrast to cathodes used in cylindrical RAM™ cells, the mechanical stability is a significant issue for the preparation of flat plate cathodes. Therefore, the choice of an appropriate binder, e.g. Oppanol, is very important. In this work, an improved preparation process of flat plate RAM™ cathodes was developed by investigating the single steps of the preparation method. It was further demonstrated that the most critical factor of zinc electrode performance was the electrolyte content of the anode gel. Best overall cell performance was achieved at 40% zinc amount and a Zn/ZnO ratio of 5.0, in combination with an electrolyte content of 50.5%. In order to stabilise the γ-structure of manganese dioxide and to enhance rechargeability, the addition of barium compounds was also studied. Cell cycling has shown that flat plate RAM™ cells with BaSO 4-modified cathodes outperformed control cells by 24%, mainly because of the minimised fade of discharge capacity. Moreover, the admixture of barium manganate to the cathode yielded more than 15% capacity improvement after 25 cycles, compared to the barium sulfate additive.

New advances on bipolar rechargeable alkaline manganese dioxide–zinc batteries

Bipolar rechargeable alkaline manganese dioxide–zinc (RAM) batteries are produced in the laboratory. These are obtained through minimizing the passivation problems associated with the zinc electrode, which is considered to have a limiting effect on the charge–discharge cycle performance. To overcome this, different tin alloys are employed in the zinc negative electrode (anode). A relationship is observed between the tin alloying elements, as current-collectors, and gas evolution during the cycling. A copper–tin–zinc ternary alloy (trademark: Optalloy) displays better corrosion resistance and a higher hydrogen overvoltage, when used as the anode current-collector. To increase the electrochemical reversibility and electronic conductivity of the anode mass, porous zinc is treated with Optalloy. This is to obtain a modified zinc electrode, which is found to be effective in terms of raising the cycle performance of the bipolar RAM batteries. Moreover, optimum electrical contact between the electroactive materials and the conductive carbon-filled polyethylene matrix is achieved through coating graphite on the cathode as well as electroless plating of copper on the anode side. It is evident that copper acts as an underlayer for the current-collector.

Triethanolamine as an additive to the anode to improve the rechargeability of alkaline manganese dioxide batteries

Rechargeable alkaline manganese dioxide batteries use a zinc paste anode which undergoes shape change during charging, effecting its activity. A study on triethanolamine (TEA) as an additive to the zinc anode to control its shape change and retain activity is made. Voltammetric studies showed the potential of TEA in controlling shape change. Rechargeable alkaline manganese dioxide batteries are made in the laboratory and their cycle life characteristics are compared with and without TEA in the anode. An improvement is noticed in the cycle life capacity of the rechargeable alkaline manganese dioxide batteries with TEA especially after 12th cycle.

00/02643 The mechanism of capacity fade of rechargeable alkaline manganese dioxide zinc cells

00/02643 The mechanism of capacity fade of rechargeable alkaline manganese dioxide zinc cells

The mechanism of capacity fade of rechargeable alkaline manganese dioxide zinc cells

Recent experiments showed, that in contrast to traditional opinion, if the cathode was protected by anode limitation the capacity fade of Rechargeable Alkaline Manganese Dioxide Zinc (RAM™) cells was not caused by the EMD cathode, but by the gelled zinc anode. The key is the electrolyte. The cathode competition for the electrolyte and the increasing requirement of chemically formed ZnO for more electrolyte caused an electrolyte deficiency at the front face of the anode and finally caused precipitation of zincate and passivation of zinc. The crust is a mixed material of precipitation and passivation products. The low solubility ZnO is formed by decomposition of electrochemically generated zincate ions [Zn(OH) 4] 2− and also by recombination of zinc with oxygen during overcharge. The progressively thickened “crust” at the front face of the anode increases the resistance, then finally causes the cell to fade. The crusting is a redistribution of active material and electrolyte between the front and rear of the cylindrical gelled zinc anode. More electrolyte and proper charging can delay such a “crusting” phenomenon.

Rechargeable alkaline manganese dioxide cells. A test report

The rechargeable alkaline MnO 2 (RAM) system has now been commercially available for several years. The Canadian Department of National Defence is interested in determining if the low cost RAM system is technically capable of replacing existing cells and batteries now in use. A preliminary study identified sufficient candidate batteries in use within the Department whose performance requirements compared favourably with RAM manufacturers' claims. Further study was warranted. Replacement cost savings could be significant. A study is now in progress that is aimed at determining how well the RAM technology actually performs. This paper presents test results that illustrate how RAM cells compare to primary alkaline cells and nickel/cadmium. The majority of the work is focused on the ‘AA’ size products from Rayovac and Pure Energy: tests were also conducted on Rayovac ‘D’ cells.

Rechargeable Alkaline Manganese Dioxide Batteries: I . In Situ X‐Ray Diffraction Investigation of the (EMD‐Type) Insertion System

The electrochemical insertion and deinsertion of H+ was investigated by studying its influence on the evolution of the crystallographic structure of of EMD type (electrochemical method deposition) during the discharge and recharge processes of an alkaline battery, using in situ x‐ray diffraction. During the first discharge, proton insertion up to H+ per with concomitant electron transfer causes an expansion of the crystalline cell. The lattice expansion is attributed to the reduction of Mn4+ ions to Mn3+ ions which have a larger ionic radius. Between 0.5 to 0.8 H+ inserted the long‐range order is lost and the presence of a quasi‐amorphous phase which could not be identified is detected. This amorphous phase is reduced to (or ) and to when more than 0.8 H+ is inserted. On recharge, the is oxidized to (or ) leading to poor cycling of the battery. When the discharge is limited to 0.8 H+the battery can be recharged and cycled many times. Still more cycles can be obtained when the discharge is limited to 0.5 H+, corresponding to the range where the structure is retained. In this range, strong hysteresis in the voltage curves indicated that while there is structural reversibility, structural changes arise at different voltages on discharge and recharge.

The effect of the amount of electrolyte in the anode gel on the rechargeability of alkaline manganese dioxidezinc cells

The zinc-limited anode technology for rechargeable alkaline manganese dioxidezinc cells is well known. Attempts have been made to relate the rechargeability of these cells with the amount of electrolyte available in the anode gel. The rechargeability of the cells is found to increase with the amount of electrolyte up to 35 – 40% of the dry weight of the anode mass. Further increases in the amount of electrolyte were found to be detrimental to the rechargeability of the cells. Analysis of cathodes after running several cycles shows higher amounts of zinc in those from cells with greater amounts of electrolyte. This could be due to haeterolite formation in the cathode which poisons it thus explaining the reduced rechargeability with excess electrolyte.