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Lithium Manganese Dioxide Battery

Lithium ions are inserted into manganese di, just as for Li/V2O5 cells, but only one discharge plateau is present. The system is low pressure and small format, low rate cells are in widespread use.

Spirally wound, high rate cells are presently gaining acceptance. However, the electrolyte used in these cells is highly inflammable (usually mixed solvents such as propylene carbonate and dimethoxyethane with lithium perchlorate) and a safer electrolyte is desirable. Cells have been known to burn fiercely for over two minutes following venting caused by electrical abuse. One method being used to avoid venting is the use of a porous separator that becomes impervious at a particular temperature, shutting down the cell reactions. Otherwise, Li/MnO2 may displace Li/SO2 in certain applications that do not require a high rate at low temperatures.

These batteries are ideal for electronic equipment requiring high rate pulses (e.g., photoflash), as well as other sophisticated devices requiring continuous operation or memory backup. Li/MnO2 cells are available in two configurations:

The Li/MnO2 coin cells range in capacity from 76 mAh to 500 mAh. The spiral-wound cylindrical cells are available in 160 mAh and 1.4 Ah sizes.

The cell reaction involves the oxidation of lithium metal at the anode to produce positively charged lithium ions (Li+) and electrons (e-). The Li+ ions go into solution and diffuse through the electrolyte and separator to the cathode. Electrons travel through the external circuit and arrive at the cathode where MnO2, Li+ ions and electrons combine. The MnO2 is reduced from the tetravalent to the trivalent state. The solid discharge reaction product remains in the cathode. No gases are evolved during discharge to cause a pressurized condition. The LiMnO2 global cell reaction:

Li + MnIVO2 --> MnIIIO2(Li+)