Knowing the difference in run-time performance
Carbon-zinc, also known as the Leclanché battery, is one of the earliest and least expensive primary batteries. They often come with consumer devices when the batteries are included.
Alkaline. Alkaline-manganese, also known as alkaline, is an improved version of carbon-zinc. Lewis Urry invented alkaline in 1949 while working with the Eveready Battery Company Laboratory in, Ohio, USA.
Alkaline delivers more energy at higher load currents than carbon-zinc. Furthermore, a regular household alkaline provides about 40 percent more energy than the average Li-ion but alkaline is not as strong as Li-ion on loading. Alkaline has very low self-discharge and does not leak electrolyte when depleted as the old carbon-zinc does.
In spite of this, alkaline is not totally leak-proof. All primary batteries produce a small amount of hydroxide gas on discharge and battery-powered devices must make provision for venting. Pressure buildup in the cell can rupture the seal and cause corrosion. This is visible in form of a feathery crystalline structure that can spread to neighboring parts in the device and cause damage.
Lithium Iron Disulfide (Li-FeS2) is a newcomer to the primary battery family and offers improved performance compared to alkaline. Lithium batteries normally deliver 3 volts and higher, but Li-FeS2 has 1.5 volts to be compatible with the AA and AAA formats. It has a higher capacity and a lower internal resistance than alkaline. This enables moderate to heavy loads and is ideal for digital cameras. Further advantages are improved low temperature performance, superior leakage resistance and low self-discharge, allowing 15 years of storage at ambient temperatures.
The disadvantages of the Li-FeS2 are a higher price and transportation issues due to the lithium metal content in the anode. In 2004, the US DOT and the Federal Aviation Administration (FAA) banned bulk shipments of primary lithium batteries on passenger flights, but airline passengers can still carry them on board if the lithium content if not exceeded. Each AA-sized Li-FeS2 contains 0.98 grams of lithium; the air limitation of primary lithium batteries is 2 grams (8 grams for rechargeable Li-ion). This restricts each passenger to two cells but exceptions have been made in which 12 sample batteries can be carried. (See BU-704a: Shipping Lithium-based Batteries by air.)
The Li-FeS2 includes safety devices in form of a positive thermal coefficient (PTC) that limits the current at high temperature and resets. The Li-FeS2 cell cannot be recharged as is possible with NiMH in the AA and AAA formats. Recharging, putting in a cell in backwards or mixing with used or other chemistries cells could cause a leak or explosion. (See BU-304a: Safety Concerns with Li-ion.)
Figures 1 and 2 compare the discharge voltage and internal resistance of Alkaline and Li-FeS2 at a 50mA pulsed load. Of interest is the flat voltage curve and the low internal resistance of Lithium; Alkaline shows a gradual voltage drop and a permanent increase in resistance with use. This shortens the runtime, especially at an elevated load.
Figure 1: Voltage and internal resistance of alkaline on discharge.
The voltage drops rapidly and causes the internal resistance to rise.
Courtesy of Energizer
Figure 2: Voltage and internal resistance of Lithium on discharge.
The voltage curve is flat and the internal resistance stays low.
Courtesy of Energizer
Lithium-thionyl chloride (LiSOCI2 or LTC) is one of the most rugged lithium-metal batteries. High specific energy and low weight make it suitable for medical applications and sensors. The ability to withstand high heat and strong vibration enables LTC to serve for horizontal drilling, also known as fracking. Temperatures can be high and some LTC are said to operate from 0°C to 200°C (32°F to 392°F). With a specific energy of over 500Wh/kg, LTC offers twice the capacity of the highest-capacity Li-ion. The nominal voltage is 3.50V/cell; the end-of-discharge cut-off voltage is 3.00V. The runtime is not based on capacity alone; thermal conditions and load pattern also have an effect. Constant current is more enduring than pulsed load; a phenomenon that applies to most batteries.
Like alkaline, lithium-thionyl chloride has a relatively high resistance and can only be used for moderate discharge loads. If stored for a time, a passivation forms between the lithium anode and the carbon based cathode that dissipates when applying a load. This layer protects the battery by granting low self-discharge and a long shelf life. (See BU-701: How to Prime Batteries.)
LTC is one of the most powerful battery chemistries and it should only be used by trained workers with adequate support. For safety reasons, this battery is not used in public applications and in consumer devices.
Lithium manganese dioxide (MnO2 or Li-M) has similar qualities to LTC but has a lower specific capacity and safe for public use. The voltage is 3.0–3.30V and the specific energy is about 280Wh/kg. Li-M is economically priced and has a long-life. It is suitable for moderate loads but can deliver high pulse currents. Operational temperature ranges from -30°C to 60°C (-22°F to 140°F). Typical uses are meter sensing, medical devices, road toll sensors and cameras.
CAUTION The chemical components that provide high energy density to lithium-based batteries can also cause safety hazard if misused. LTC and Li-M are safe but workers handling these batteries must be familiar with the safety precautions, transportation and disposal. Make certain that the batteries are protected from heat, short circuit, and all physical or electrical abuses.
Last Updated 2015-09-07
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