Lithium batteries

Lithium manganese dioxide cells

The negative electrode is lithium and the positive electrode is manganese dioxide. The lithium manganese dioxide system is the most widespread of all systems. The advantages of the lithium cell include high voltage, high energy density, flat discharge curve, very good storage behavior and the fact that it can be used over a wide temperature range. In addition, it is available in all forms of construction. Lithium batteries have minimal self-discharge, making them suitable for long-term applications in electronics, photographic equipment, telecommunications, and metrology. A new development is the thin flat lithium cell, also known as lithium paper. This battery measures less than 0.4 millimeters and is perfect for fitting into credit card-sized smart cards. Smart cards are active cards with a microchip with battery and integrated display.

The combination of lithium with a low-freezing electrolyte such as non-flammable thionyl chloride (SOCl2) produces high energy density, low weight, low self-discharge and operation under extreme conditions. Depending on the particular cell type and design, LiSOCl2 cells can be used in a variety of applications, e.g., backup systems, metering devices, security systems. Primary lithium batteries come in a variety of construction types.

Coil
In the coil structure, the cathode is cylindrical. The anode is rolled onto the inner wall of the housing, which has safety advantages, since the current from an unintentional short circuit cannot be very high. The heat that is generated mainly on the contact surface between the anode and cathode can be dispersed externally. High pressure buildup cannot occur, regardless of whether the cell has a safety valve or not.

It is perfectly suited to long-term applications of 5-20 years, with a discharge curve having several base currents of the order of µA and short periodic pulses of the order of seconds, usually in the range of 5-150 mA.

Spiral
Spiral construction includes specific designs that can operate at very high temperatures with applications in oil and gas, for example. The cells are designed for applications that require short periodic pulses of up to 4 A.

Button
In flat cell constructions, the anode is pressed into the base of the container. The cathode is a disc positioned above the anode, separated from the anode by a separator. This construction has the same safety advantages as the coil structure. Lithium button cells are constructed similarly, except for the sealing system (plastic seal).

Lithium polycarbonate fluoride batteries have a high energy density and exhibit stable performance at relatively high ambient temperatures.

High temperature lithium polycarbonofluoride batteries.

The materials featured in these coin-type batteries have been replaced, and the operating temperature has been significantly increased by using a high-boiling point electrolyte.

Characteristics of primary lithium batteries
Lithium, with a specific gravity of 535 kg/m3, is the lightest of the metals and floats on water. Lithium has the highest electrochemical potential, making it the most reactive metal. These properties give lithium the potential to achieve very high energy and power densities, allowing for the construction of batteries with very long lifespans. Because lithium reacts violently with water, as well as with nitrogen in the air, this requires the construction of sealed batteries with safety valves, which release pressure to prevent uncontrolled explosion.

Advantages:

• High energy density up to 500Wh/kg
• Low self-discharge (storage life up to 20 years)
• Operating at temperatures between -60°C and +85°C special batteries up to +150°C
• “Plateau” discharge curve (stable voltage)

The chemistries for lithium batteries are:

• Lithium Manganese Dioxide
• Lithium-thionyl (Li-SoCl2) batteries have a lithium anode and a liquid cathode with a porous carbon current collector filled with thionyl chloride (SOCl2)

The construction can be with electrodes placed like a coil for applications with low, long-term currents or with spiral electrodes for power applications, both variants providing a voltage of 3.6V.

• Lithium-sulfur dioxide (Li-SO2) for our LO/G cells (2.8 V)
• Lithium-manganese dioxide (Li-MnO2) for our LM/M cells (3.0 V)
• Lithium iron disulfide (Li-FeS2) is a battery built to deliver performance, a newcomer to the primary battery family and offers improved performance compared to alkalines. Lithium batteries typically deliver 3 volts and higher, but Li-FeS2 has 1.5 volts to be compatible with AA and AAA formats. It has a higher capacity and lower internal resistance than alkaline. It allows moderate to heavy loads and is ideal for digital cameras. Additional benefits include improved low temperature performance, superior leak resistance and low self-discharge, allowing for 15 years of storage at ambient temperatures. The disadvantages of Li-FeS2 are a higher price and transportation problems due to the lithium metal content in the anode. In 2004, the US DOT and the Federal Aviation Administration (FAA) banned the bulk shipment of primary lithium batteries on passenger flights, but airline passengers can still carry them if the allotted lithium content is not exceeded.

Typical chemistries are lithium Manganese dioxide, lithium sulfur dioxide, lithium thiyl chloride (see below), and lithium oxygen (see below), but other variants are available. The available cell voltages are between 3 and 4 Volts. Cell packaging includes coin cells and cylindrical packages. Thin film cells based on ceramic or flexible substrates are also available. Advantages: High energy density, double that of premium alkaline batteries, light weight, high cell voltage, flat discharge characteristic, low self-discharge, very long shelf life, very long service life (15 to 20 years for lithium thionyl chloride). Wide operating temperature range (-60°C to +85°C for lithium sulfur dioxide), excellent durability, small cell size. Disadvantages: high cost. Applications: Computer memory protection, Medical implants, Cardiac pacemakers, Defibrillators, Utility meters, Watches, Cameras, Calculators, Car keys, Security transmitters, Smoke alarms, Aerospace applications.

Due to its superior performance characteristics, lithium technology is replacing older, traditional technologies in an ever-widening range of applications. Costs more expensive than primary consumers Leclanché and alkaline Lithium-manganese dioxide batteries. Anode: Lithium foil Cathode: Manganese dioxide Electrolyte: Separator sheet impregnated with electrolytic salts Cell voltage: 3 volts (most common non-rechargeable lithium cell). Lithium iron disulfide cell anode: lithium foil cathode: iron disulfide with contact electrolyte with aluminum cathode: separator sheet impregnated with electrolytic salts. Designed to be a drop-in replacement for zinc or alkaline batteries cell voltage: 1.5 volts. Often called a “voltage compatible” lithium cell, these have a higher energy density than the cells they replace and are suited for high current applications. Lithium chloride cell is the highest energy density of all lithium type cells and has a service life of 15 to 20 years. Lithium iodine cell offers excellent safety and long life. Uses only solid components and the separator is self-healing if cracks occur. High internal impedance limits its use to low leakage applications. Used for most implanted pacemakers. Lithium air cell Similar to zinc air cells they have a very high theoretical energy density. The anode, a lithium metal foil pressed into a nickel mesh current collector, is electrochemically coupled to an unlimited supply of atmospheric oxygen through an air cathode. The air cathode is a layered electrode with two layers of carbon containing catalysts, such as Manganese, separated by a nickel mesh current collector. A PTFE membrane is used to repel water from the atmosphere while allowing oxygen diffusion. Non-aqueous electrolytes, such as LiPF6, must be used due to the interaction of lithium with water. The cell voltage is 3.0 Volts, and the storage capacity is limited by the lithium anode. The cell has a flat discharge curve and a long storage life. Performance varies greatly with temperature. Rechargeable versions are also possible. See note on lithium toxicity.

Passivation of lithium batteries

Passivation is a phenomenon characteristic of lithium batteries. It consists of the formation of a thin layer on the surface of the lithium anode upon contact with the electrolyte. The thin layer acts as an “insulator” during battery storage, which makes the storage period at least 10 years because self-discharge is practically non-existent. However, under long-term storage conditions, at temperatures above 25°C, the passivation layer may become thicker and then the battery will experience a delay in reaching its nominal voltage. When such a phenomenon is observed, it is sufficient to discharge the battery with a current close to the maximum allowed current and the ions will cross the passivation layer, making it more porous, and the battery will reach the voltage of an unpassivated battery.