Self-discharge rate

Self-Discharge Processes. The shelf life of the lead—acid battery is limited by self-discharge reactions, first reported in 1882 (46), which proceed slowly at room temperature. High temperatures reduce shelf life significantly. The reactions which can occur are well defined (47) and self-discharge rates in lead—acid batteries having immobilized electrolyte (48) and limited acid volumes (49) have been measured. 

Ikoma et al. carried out a detailed investigation to study the self-discharge mechanism and contribution of separators.They used nonwoven fabric made of conventional polyamide (FA), FF (with surfactant), and a nonwoven fabric whose main material was sulfonated-FF (hydrophilic) as separators. When nonwoven fabric made of chemically stable sulfonated-FF is used as a separator instead of a conventional polyamide separator, the self-discharge rate of the NiMH battery was strongly depressed, to the same level as that of NiCd battery. 2 >o-242.243... 

Miniature batteries based on aqueous, non-aqueous and solid electrolytes are manufactured as power sources for microelectronics and other miniaturized equipment. In Fig. 1.2, the sizes and shapes of some representative button cells are shown. A typical application for such cells is in the electric watch, where the oscillator circuit draws a continuous current of 0.2-0.6 pA and depending on the type of frequency divider and display, the complete unit may require a total of up to 0.5-2.0 pA for operation. Hence the total amount of electrical energy consumed in driving the watch for a year is in the range 15-60 mWh. At present, batteries are manufactured which last for 5-10 years. Watch batteries must have exceptionally low self-discharge rates and very reliable seals to prevent leakage. Further, they... 

The self-discharge rate of RAM cells is approximately 0.01% per day, which gives them a clear superiority over nickel-cadmium and nickel-metal hydride cells (Fig. 6.19). 

Solvents that meet all or most of the criteria are propylene carbonate, dimethyl sulfoxide, 4-butyrolactone, acetonitrile, sulfur dioxide, thionyl chloride, and phosphorus oxychloride. Certain other solvents, with fairly low s values, such as tetrahydrofuran, dimethoxyethane, and 1,3-oxolane are used in conjunction with a high s solvent, in order to reduce the viscosity without impairing excessively the other desirable properties of the co-solvent. All these solvents are on the List, with properties shown in the tables mentioned. Commercial implementation of such batteries has been highly successful, with energy densities of primary dischargeable batteries of 0.3 W h g 1 or 0.5 W h cm 3 and a self discharge rate of < 2% per year of the open-circuit battery being achieved. 

Lower self-discharge rates, especially in primary metal anode systems such as Li/Mn02 and Li/S02. 

Similar electrolytes to Li/Cl ) cell can be used. Numerous coin-cell, spiral-wound and bobbin configurations are available, as well as three-cell-in-series prismatic 9 V [27], As with most other Li metal anode primary systems, the very low self-discharge rate affords many years of shelf life in standby usage. Therefore, applications such as smoke detectors are very popular for this system. 

Very high self-discharge rate when exposed to air, as the zinc spontaneously reacts with oxygen, and the water in the battery (in the electrolyte solution) tends to dry out. 

The self-discharge rate of a Li-ion battery is usually lower compared to those of other rechargeable batteries. The capacity loss during storage is largely dependent on the storage temperature as well as the... 

The shelf life of Ni-Cd batteries is largely determined by the cell self-discharge rate. The mechanism of the... 

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