Cell voltage mercury zinc

Clark cell — Electrochemical -> standard cell showing a particularly stable and reproducible cell voltage. A zinc and a mercury electrode (half-cell) are combined according to... 

The volumetric ampere hour capacity of mercuric oxide-zinc cells is higher than that of lithium-based systems. However, in many cases using two lithium cells in parallel or one larger lithium cell will give the same ampere hour capacity that can be achieved in an equal or even smaller volume than an equivalent two-cell series mercury-zinc battery of similar voltage. This is illustrated in Table 2.7, which gives a... 

The nickel—zinc combination has a high cell voltage (about 1.75 V), which results in a very favorable energy density compared to that of nickel—cadmium or lead—acid. Additionally, zinc is relatively inexpensive and, in the absence of mercury additive, is environmentally benign. The nickel—zinc system was discussed as early as 1899 (4). There has been a resurgence of interest in the system for electric vehicles, but the problems of limited cycle life have not been completely overcome. 

Figure 8.1 Typical voltage discharge characteristics of mercury-zinc cells under continuous load cenditionsat 21 °C. At 1.25 V, equivalent current drains for the resistances are 15 2, 83 mA 25 2,50 mA 32 2, 40 mA 42 2, 30 mA 50 2,25mA 60 R, 20 mA (Courtesy of Union Carbide)...

Figure 30.10 Mallory Duraceil mercury-zinc cells and batteries, 1.35 V voltage-dischargecurves-eslimated average service at 2YC...

A general review of the types of application found for mercury-zinc batteries available from one particular supplier (Crompton-Parkinson) is found in Table 37.1. together with information on capacities available and battery weights. Voltages vary between 1.35 and 97.2 V and capacities vary up to 28Ah. These batteries are of the button cell or cylindrical design. 

The voltage, eapaeity and physical characteristics of some of the Mallory Duracell range of mercury-zinc cells and batteries are shown in Tables 55.5 and 55.6. Battery types 304116 (12.6V) and TR431 (11.2V)... 

Figure 55l3 Mallory Duracell mercury-zinc cells and batteries, voltage discharge curves estimated average service at 21 °C versus volage. Current drains at 1.25 V. (a) 1.35V, BOmAh to 0.9V on 25000(2 at 20°C (b) 1.4V, 85mAh to 0.9V on 1250(2 at 20°C impedance (average at 15% discharge) 7.6(2 at 10 Hz, 70 (2 at 1000 Hz, 6.0(2 at 100000 Hz (Courtesyof Maiiory)...

Two common types of button batteries both use a zinc container, which acts as the anode, and an inert stainless steel cathode, as shown in Figure 11.11 on the next page. In the mercury button battery, the alkaline electrolyte paste contains mercury(II) oxide, HgO. In the silver button battery, the electrolyte paste contains silver oxide, Ag20. The batteries have similar voltages about 1.3 V for the mercury cell, and about 1.6 V for the silver cell. 

The main features of the zinc silver oxide cell are similar to those of the zinc mercury(II) oxide system. The principal difference apart from cost is the higher open circnit voltage the emf calculated from the standard free energies of formation of ZnO and Ag20 is 1.593 V, in close agreement with the open circuit voltage of commercial cells of 1.60 V. 

The alkaline cell has an open-circuit voltage of 1.5 V that can deliver 150 Wh/kg and 460 Wh/1. The reactions have fast kinetics and can deliver full capacity, even at high-rate discharges. Since its introduction in 1959, there has been a steady increase in performance of the alkaline cell as new materials and cell components were incorporated into the structure. The present alkaline cell designs are based on the use of nanostructured electrolytic manganese dioxide, a thinner polymer gasket seal with sealant to increase internal volume and improve shelf Ufe. Mercury has been eliminated by using new zinc alloy compositions. These improvements have resulted in about a 40 % improvement in performance over the same-size cells produced in 1959. 

The most efficient dry cell is the mercury cell, which has an excellent stabilized voltage. Developed in 1942 by Ruben, it consists of zinc, which dissolves and becomes the negative electrode and mercuric oxide, which is reduced to mercury at the positive electrode. The overall cell, which has no salt bridge, can be represented as follows ... 

Cadmium/Mercuric Oxide Battery. The substitution of cadmium for the zinc anode (the cadmium/mercuric oxide cell) results in a lower-voltage but very stable system, with a shelf life of up to 10 years as well as performance at high and low temperatures. Because of the lower voltage, the watthour capacity of this battery is about 60% of the zinc/mercuric oxide battery capacity. Again, because of the hazardous characteristics of mercury and cadmium, the use of this battery is limited. 

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