Consumer (sometimes referred to as commercial) lithium (Li) batteries offer better performance compared with lower-cost alkaline, nickel-cadmium (NiCd), or nickel metal hydride (NiMH) alternatives, but industrial Li batteries are even higher in performance.
This FAQ looks at examples of chemistries for primary and secondary Li batteries in consumer and industrial devices including the use of hermitic packaging for some industrial battery designs and looks at considerations related to battery grading when assembling Li-ion battery packs. It closes with a glance at the dozen battery standards that the US Consumer Product Safety Commission (CPSC) has participated in developing related to batteries in consumer products.
Lithium iron disulfide
Lithium iron disulfide (LiFeS2) primary batteries were developed to replace AA alkaline cells in consumer applications. The open circuit voltage of LiFeS2 is 1.8 V, the nominal rated voltage being 1.5 V, making it suitable for use in devices designed to use alkaline or nickel-based 1.5 V batteries. Consumer LiFeS2 cells are designed to meet all the ANSI specifications for a 1.5 V cell. While standard 1.5 V alkaline cells use a bobbin construction, LiFeS2 cells use a spiral construction that has 20-times the interfacial surface area compared with a bobbin cell and delivers strong high-rate performance, while the chemistry itself offers superior low-temperature characteristics compared with standard alkaline cells (Figure 1).
These cells have a Li metal anode and a cathode of iron disulfide on an aluminum foil substrate. The electrolyte is a lithium salt in an organic solvent. The electrodes in LiFeS2 cells are isolated by a microporous polyolefin membrane that supports ion flow under normal operation but restricts it during abuse conditions, supporting both good performance and safety. These cells include two additional safety components. Under very high drain rates, the cells’ internal temperature increases and a positive temperature coefficient (PTC) thermal switch limits the current when the temperature reaches 85 to 95 °C. The PTC recloses when the temperature drops to a safe level. Additionally, a pressure relief vent opens at 130 to 160 °C in the event of thermal runaway. These cells are rated for operation from -40 to 60 °C. Due to their high performance and high drain capabilities, these cells are suited for a range of consumer applications like:
- high-drain digital cameras and flash units
- stud finders, laser levels, and high-power portable LED lighting for construction sites
- remote control and motorized toys
- high-power game controllers for Wii and Xbox
- global positioning systems for hikers and other outdoor gear
Lithium-manganese dioxide (LiMnO2) is a highly versatile primary chemistry. LiMnO2 cells deliver higher energy on a weight and volume basis compared with LiFeS2 and alkaline cells. LiMnO2 uses a metallic lithium anode and a solid manganese dioxide cathode immersed in a non-corrosive, non-toxic organic electrolyte. These cells have an open circuit voltage of 3.3 V and a normal operating voltage of 2.5 to 3.0 V depending on the device’s current drain and ambient temperature. LiMnO2 is used in consumer, commercial, and industrial applications. It’s available in cylindrical, button, and prismatic shapes and is used to produce 9 V batteries for consumer devices. LiMnO2 cells can have low self-discharge making them useful for backup power applications. For example, a LiMnO2 9 V battery can provide up to a 10-year backup battery in AC-powered smoke detectors. It’s the most common primary Li chemistry used in consumer batteries. Typical LiMnO2 form factors and applications include:
- Button (Figure 2)
- tire-pressure monitoring system (TPMS)
- electronic toll collection system
- luggage tracking tags
- real-time clock backup power
- blue-tooth headsets
- instruments, sensors, and beacons
- High-capacity cylindrical (bobbin-type)
- water, gas, and electricity meters
- memory backup power sources for office and factory automation equipment
- main power sources and memory backup power sources for car electronics
- various memory backup power sources
- High-power cylindrical (spiral-type)
- automatic cameras with flash
- video cameras
- electronic locks
- medical and industrial equipment
Lithium thionyl chloride
Lithium thionyl chloride (LiSOCl2) batteries have an open circuit voltage of 3.6 V and a normal operating voltage of 2.8 to 3.3 V depending on the device’s current drain and ambient temperature. LiSOCl2 cells deliver higher energy on a weight and volume basis compared with LiMnO2. They are primarily used in industrial, medical, and military systems. Some high-end consumer devices also turn to LiSOCl2 batteries for power. Most LiSOCl2 batteries are rated for operation from -55 to +85 °C, with some rated for operation up to 130 °C. They offer the highest energy density of any primary chemistry delivering up to 650 Wh/kg and 1280 Wh/dm³. LiSOCl2 batteries can have self-discharge rates of less than 1% per year. They are available in hermetically sealed cases for long shelf life and safety.
High-performance seals are an important aspect of high-reliability Li battery construction. Glass-to-metal sealing (GTMS) hermetic protection is often employed in reliability-critical industrial and other applications. GTMS supports gas tight caps for a range of energy storage devices including primary and secondary Li batteries, electrolytic capacitors, and supercapacitors. It also eliminates electrolyte leakage and dry-out and moisture intrusion.
Lower performance and lower cost organic polymer, rubber, and other sealing technologies are suited for a wide range of applications but can experience aging and degraded performance over time, especially under harsh environmental conditions. GTMS systems are optimized for specific electrolytes and application requirements. The use of GTMS can simplify lid assembly, reducing the number of components and further increasing cell reliability. Hermetic seals can be especially important in long-life Li batteries like the primary Li designs rated for 20-to-40-year lifetimes. In addition, GTMS supports chemical stability in the battery, autoclavability, and high-temperature resistance (Figure 3).
Consumer vs industrial Li-ions
There’s a wide range of Li-ion chemistries each of which offers varying tradeoffs between energy density, cycle life, operating temperature ranges, and other specifications. That makes a comprehensive discussion of consumer versus industrial Li-ion batteries beyond the scope of this necessarily brief FAQ. Consume-grade Li-ion batteries have operating lives as short as a few years and 500 recharge cycles. They are rated for operation from 0 to 40 °C and are limited in their ability to support high current pulses.
By contrast, industrial-grade Li-ion batteries have higher initial costs but can lower the total cost of ownership for remote applications in rugged environments. Industrial Li-ions can operate for up to 20 years and 5,000 recharge cycles. They are rated for operation from -40 to 85 °C and can consistently deliver high pulses required to power two-way wireless communications and other power-hungry applications. Like their LiSOCl2 cousins, industrial Li-ions feature rugged construction including hermetic seals not found in consumer-grade batteries (Table 1).
Lithium cell grades
Not all industrial Li battery cells offer equal performance. Even minor differences can be important when assembling high-performance battery packs. There are a variety of cell grading schemes. A common method is to identify cells as Grade A, Grade B, and Repurposed (used). Repurposed cells can be further broken down into multiple categories indicating suitability for various applications like utility-scale energy storage systems.
Using closely matched cells can be an important consideration when assembling high-performance battery packs. One tradeoff is between individual cell balancing and cell matching. A weak cell can cause other cells in the pack to be stressed during discharge. During charging, a weak cell can become overcharged, eventually resulting in the failure of the weak cell. Using closely matched cells can be an economic alternative to using balancing and matching circuitry for each individual cell. A battery pack with well-matched cells can be expected to operate for over 5 years while a pack with Grade B cells will have a much shorter expected lifetime.
Consumer battery standards
Although not exhaustive, the following is a list of standards related to batteries in consumer products where the US CPSC has participated in development activities:
- IEEE 1625 – Standard for Rechargeable Batteries for Multi-Cell Computing
- IEEE 1725 – Standard for Rechargeable Batteries for Mobile Telephones
- ANSI/CAN/UL 2272 – Electrical Systems for Personal E-Mobility Devices
- ANSI/NEMA C18 – Safety Standards for Primary, Secondary, and Lithium Batteries
- ASTM F963 – Standard Consumer Safety Specification for Toy Safety
- ASTM F2951 – Standard Consumer Safety Specification for Baby Monitors
- UL 1642 – Standard for Safety for Lithium Batteries
- UL 2054 – Standard for Household and Commercial Batteries
- UL 2056 – Outline of Investigation for the Safety of Power Banks
- UL 2595 – Standard for Safety for General Requirements for Battery-Powered Appliances
- UL 4200A – Standard for Safety for Products that Incorporate Button or Coin Cell Batteries Using Lithium Technologies
- UL 60065 – Standard for Audio, Video, and Similar Electronic Apparatus – Safety Requirements
A variety of battery chemistries are available for consumer and industrial applications. Some chemistries like LiFeS2 primary batteries are primarily used in consumer applications, some like LiSOCl2 are primarily used in industrial applications and others like LiMnO2, and various Li-ion chemistries are available in designs optimized for either consumer or industrial applications. Overall, consumer batteries place a greater emphasis on low cost while industrial designs have a stronger focus on environmental ruggedness and performance specifications.
Batteries, U.S. Consumer Products Safety Commission
Battery and Capacitor Lids, Schott
Cylindrical Primary Lithium, Energizer
Lithium Metal Battery, Wikipedia
National Blueprint for Lithium Batteries, 2021–2030, U.S. Department of Energy
Not All Lithium Cells are the Same, Invicta Lithium Batteries
Understanding battery self-discharge, Tadiran Batteries