Secondary battery cycle life

Another important parameter for describing a secondary electrochemical cell is the achievable number of cycles or the lifetime. For economic and ecological reasons, systems with a high cycle life are preferred. The number of cycles indicates how often a secondary battery can be charged and discharged repeatedly before a lower limit (defined as a failure) of the capacity is reached. This value is often set at 80 percent of the nominal capacity. To compare different battery systems, besides the number of cycles, the depth of discharge must be quoted. 

An Li-Al Alloy was investigated for use as a negative electrode material for lithium secondary batteries. Figure 41 shows the cycle performance of a Li-Al electrode at 6% depth of discharge (DOD). The Li-Al alloy was prepared by an electrochemical method. The life of this electrode was only 250 cycles, and the Li-Al alloy was not adequate as a negative material for a practical lithium battery. 

Fig. 11.15, the loss of capacity with cycle life is shown. The available energy capacity can be calculated as 35 kW h at the beginning of the battery s life and 21 kW h at the end. The energy density of 86 W h kg at the beginning is attractive compared with the conventional secondary batteries of 40 W h kg or less. The energy capability with cycling must be improved for practical applications. 

Nickel—hydrogen batteries offer long cycle life that exceeds that of other maintenance-free secondary battery systems and accordingly makes it suitable for many space applications. Three types of separator materials have been used for aerospace Ni—H2 cells— asbestos (fuel-cell-grade asbestos paper), Zircar (untreated knit ZYK-15 Zircar cloth),and nylon. 

The first practical silver—zinc battery was developed more then 60 years ago. Since then, primary and secondary silver—zinc batteries have attracted a variety of applications due to their high specific energy, proven reliability and safety, and the highest power output per unit weight and volume of all commercially available batteries. However, they find very limited use in commercial applications, because of their high price and limited cycle life. Development of a battery separator which will improve the performance and life of zinc based alkaline cells has been... 

The nickel—zinc (NiZn) system is attractive as a secondary cell because of its high energy density and low material cost and the low level of potential pollutants contained. The widespread use of nickel-zinc batteries, particularly as electric vehicle power sources, would be strongly enhanced by significantly extending the deep-discharge cycle life beyond the current level of 100—300 cycles. Considerable work has been done in the past to develop a suitable separator for nickel— and silver—zinc batteries. 272 An excellent discussion of separator development is contained in a comprehensive review. 2 ... 

Chartouni, D. Kuriyama, N. Kiyobayashi, T. Chen, J. Air-metal hydride secondary battery with long cycle life. Journal of Alloys and Compounds (2002) 330-332, 766-770. 

So far, it seems that the cycle life obtained for these Mg insertion cathodes is rather low. For instance, Novak et al. [433,434] showed that cathodes such as MgxV308 could be cycled reversibly more than 50 times, but the capacity decreases to about 50% of its initial capacity (=150 mAh/gr) after 20 cycles. However, it is clear that this work presents an important breakthrough, as it shows the feasibility of R D of insertion cathodes for secondary Mg batteries. Further promising work in this field was demonstrated recently by Sanchez and Pereira-Ramos [435], who showed that Mg can be inserted reversibly, by electrochemical means, into the cation-deficient oxide mix Mn2.15Coo.37(up to 0.23 Mg per mole oxide) from PC/Mg(C104)2 solutions at potentials around 2.9 V versus Li/Li+. 

Yamaki, J., Design of the lithium anode and electrolytes in hthium secondary batteries with a long cycle life, in Lithium Ion Batteries Fundamentals and Performance, M. Wakihara and Y. Yamamoto, Eds., Kodansha Ltd., Tokyo, 1998, p. 67-97. 

The characteristics of batteries include the values of some properties of the batteries that are necessary for the selection and use of the batteries in a specific application. The characteristics of the batteries are defined by the chemistry of the battery, that is, by the materials used for the construction of the battery (electrodes and electrolyte). The most common properties or characteristics used for the selection of a battery system are energy density, capacity, operating voltage, operating temperature, service life, cycle life (for secondary... 

---