Lithium battery
Lithium battery
Description
The term “lithium battery” refers to a family of different chemistries, comprising many types of cathodes and electrolytes. One type of lithium cell having a large energy density is the lithium-thionyl chloride cell. In this cell, a liquid mixture of thionyl chloride (SOCl2) and lithium tetrachloroaluminate (LiAlCl4) acts as the cathode and electrolyte respectively. A porous carbon material serves as a cathode current collector which receives electrons from the external circuit. However, lithium-thionyl chloride batteries are generally not sold to the consumer market, and find more use in commercial/industrial applications, or are installed into devices where no consumer replacement is performed. Lithium-thionyl chloride batteries are well suited to extremely low-current applications where long life is necessary, e.g. wireless alarm systems.
The most common type of lithium cell used in consumer applications uses metallic lithium as anode and manganese dioxide as cathode, with a salt of lithium dissolved in an organic solvent.
Disassembled CR2016 battery
1st: Anode cup, upside down, spent lithium partially scratched off
2nd: Separator, a thin layer of porous material soaked with electrolyte – lithium salt in an organic solvent
3rd: Cathode, a tablet of manganese dioxide
4th: Cathode can, with current collector (carbon layer) on its bottom and a gasket around its inner edge. Damaged by clumsy opening attempt.
Chemistries
Chemistry
Cathode
Electrolyte
Nominal voltage
Open-circuit voltage
Wh/kg
Wh/dm3
Li-MnO2 (Li-Mn, “CR”)
Heat-treated manganese dioxide
Lithium perchlorate in propylene carbonate and dimethoxyethane
3 V
3.3 V
280
580
The most common consumer grade battery, about 80% of the lithium battery market. Uses inexpensive materials. Suitable for low-drain, long-life, low-cost applications. High energy density per both mass and volume. Can deliver high pulse currents. Wide temperature range. With discharge the internal impedance rises and the terminal voltage decreases. Maximum temperature limited to about 60 C. High self-discharge at high temperatures.
Li-SOCl2
Thionyl chloride
Lithium tetrachloroaluminate in thionyl chloride
3.5 V
3.65 V
290
670
Liquid cathode. For low temperature applications. Can operate down to -55 C, where it retains over 50% of its rated capacity. Negligible amount of gas generated in nominal use, limited amount under abuse. Has relatively high internal impedance and limited short-circuit current. High energy density, about 500 Wh/kg. Toxic. Electrolyte reacts with water. Low-current cells used for portable electronics and memory backup. High-current cells used in military applications. In long storage forms passivation layer on anode, which may lead to temporary voltage delay when put into service. High cost and safety concerns limit use in civilian applications. Can explode when shorted. Underwriters Laboratories require trained technician for replacement of these batteries. Hazardous waste, Class 9 Hazmat shipment.
Li-SOCl2,BrCl, Li-BCX
Thionyl chloride with bromine chloride
Lithium tetrachloroaluminate in thionyl chloride
3.7-3.8 V
3.9 V
350
770
Liquid cathode. A variant of the thionyl chloride battery, with 300 mV higher voltage. The higher voltage drops back to 3.5 V soon as the bromine chloride gets consumed during the first 10-20% of discharge. The cells with added bromine chloride are thought to be safer when abused.
Li-SO2Cl2
Sulfuryl chloride
3.7
3.95
330
720
Liquid cathode. Similar to thionyl chloride. Discharge does not result in buildup of elemental sulfur, which is thought to be involved in some hazardous reactions, therefore sulfuryl chloride batteries may be safer. Commercial deployment hindered by tendency of the electrolyte to corrode the lithium anodes, reducing the shelf life. Chlorine is added to some cells to make them more resistant to abuse. Sulfuryl chloride cells give less maximum current than thionyl chloride ones, due to polarization of the carbon cathode. Sulfuryl chloride reacts violently with water, releasing hydrogen chloride and sulfuric acid.
Li-SO2
Sulfur dioxide on teflon-bonded carbon
Lithium bromide in sulfur dioxide with small amount of acetonitrile
2.85 V
3.0 V
250
400
Liquid cathode. Can operate down to -55 C and up to +70 C. Contains liquid SO2 at high pressure. Requires safety vent, can explode in some conditions. High energy density. High cost. At low temperatures and high currents performs better than Li-MnO2. Toxic. Acetonitrile forms lithium cyanide, and can form hydrogen cyanide in high temperatures. Used in military applications.
Addition of bromine monochloride can boost the