What Is a Lithium Battery?
A lithium battery is a type of chemical battery that produces electricity through a chemical reaction. Although the name is similar to that of a lithium-ion battery and is easily confused, a lithium-ion battery is a rechargeable battery based on an intercalation reaction that uses a carbon material capable of storing lithium ions as its negative electrode.
Lithium batteries, on the other hand, use metallic lithium or lithium alloys for the negative electrode and are generally non-rechargeable primary batteries.
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The positive electrode of a lithium battery can be made of manganese dioxide, graphite fluoride, or iron disulfide. Typically, when we refer to a lithium battery, we mean a lithium manganese dioxide battery.
Uses of Lithium Batteries
Lithium has the greatest tendency to cationize among all metals and is also the lightest metal. For this reason, lithium batteries are characterized by high voltage, light weight, and high energy density. They are widely used as internal power sources for clocks and memory backup in various household electrical equipment such as Blu-ray/DVD recorders, digital cameras, game consoles, rice cookers, and communication devices.
Some types also have stable discharge characteristics, long-term reliability, and excellent shelf life at high temperatures. This makes them widely used as power sources for various types of water, electricity, and gas meters and smart meters, fire alarms, security equipment, medical equipment, and other important devices.
Principle of Lithium Batteries
Lithium batteries use manganese dioxide, graphite fluoride, or iron disulfide for the positive electrode, lithium metal for the negative electrode, and an organic electrolyte made by dissolving lithium salts in an organic solvent as the electrolyte.
Lithium metal on the negative electrode is ionized from the point where it contacts the electrolyte and dissolves into the electrolyte as lithium ions, and one electron is generated for each lithium atom lithiated. The electrons then move to the conductor and the lithium ions move from the negative electrode to the positive electrode via the electrolyte, causing a chemical reaction with the cathode material.
Characteristics of Lithium Battery
Compared to other batteries such as alkaline batteries, lithium batteries have the following features:
1. Light Weight and High Voltage
While alkaline batteries have a nominal voltage of 1.5 V, manganese dioxide batteries, which are widely used, have a higher nominal voltage of 3 V. Lightweight and high-voltage, they have a high energy density and can be used in smaller devices by reducing the number of batteries from two or more to just one.
2. Low Self-Discharge and Long Battery Life
The cathode of a lithium battery is a chemically stable material that does not deteriorate easily and can maintain more than 90% of its capacity even after 10 years of storage.
In addition, a comparison of battery life in equipment requiring relatively high current (e.g., photographic equipment) shows that lithium batteries can be expected to last about twice as long as alkaline dry cell batteries. Although lithium batteries are more expensive than dry batteries, the frequency of battery replacement decreases, which may be advantageous in terms of total cost for equipment that requires a large amount of current.
However, when used in devices with low current consumption, such as calculators and TV remote control transmitters, the difference in life expectancy between lithium batteries and dry cell batteries is small, with no significant advantage.
3. Wide Temperature Range
Since the electrolyte of alkaline batteries and other batteries widely used in dry cell batteries is an aqueous solution, the reaction activity decreases in low-temperature environments. If the electrolyte freezes, the battery will not function as a battery. For this reason, the recommended operating temperature range for alkaline batteries is 5°C to 45°C.
On the other hand, lithium batteries use an organic electrolyte, which has a very low freezing point. They are also relatively stable at high temperatures, so power can be extracted over a wide temperature range. The operating temperature range for ordinary products is claimed to be -30 to 70°C, and for heat-resistant types, -40 to 125°C.
Because of these characteristics, lithium batteries are used as power sources for equipment in snowy mountaineering and for cameras and other equipment used for photography and video recording.
Types of Lithium Batteries
Generally speaking, lithium batteries are primary batteries that cannot be charged or discharged, but there are also secondary lithium batteries that can be charged and discharged. The following is an introduction to each type:
Primary Lithium Battery
Commercially available primary lithium batteries are classified into three types by shape: cylindrical lithium batteries, coin-shaped lithium batteries, and pin-shaped lithium batteries.
- Cylindrical Lithium Battery
Cylindrical lithium batteries are characterized by low self-discharge and high power output. Graphite fluoride or manganese dioxide is mainly used as the cathode material, and the output voltage is nominally 3V. Graphite fluoride has excellent long-term shelf life and is used as a power source in smart meters for gas and water. Manganese dioxide is suitable for supplying large currents and is used in photographic equipment such as cameras. Lithium batteries using iron sulfide as the positive electrode material have an output voltage of about 1.5 V and are sold as replacements for AA and AAA batteries. - Coin-Type Lithium Battery
The cathode material of coin-shaped lithium batteries is graphite fluoride or manganese dioxide. Characterized by their thinness and compact size, they are used as backup power sources for memory and clock functions in electrical products and information equipment. They are also used in keyless entry systems and ultra-compact lights in automobiles. - Pin-Type Lithium Battery
Pin-type lithium batteries are long, thin, and small, and their positive electrode material is graphite fluoride. Applications include electric floats for fishing and small radio wave transmitters.
Lithium Battery
While lithium batteries are generally primary batteries that cannot be recharged, there are also lithium secondary batteries that can be recharged by using a compound such as vanadium or titanium as the positive electrode and lithium metal or a lithium compound or alloy such as aluminum or titanium as the negative electrode, in coin form.
Not only do they have the same excellent characteristics as primary lithium batteries, but they also have excellent charge-discharge cycle characteristics. They are suitable for devices that do not want to or cannot replace lithium batteries midway. Examples of use are in solar-powered watches and backup power supplies for wristwatches.