Common-Sense FAQs About Ternary Cylindrical Lithium-Ion Batteries

What exactly are "ternary materials" in ternary cylindrical lithium-ion batteries, and why are they used?

The "ternary" refers to three key metal elements in the battery’s cathode: nickel (Ni), cobalt (Co), and manganese (or aluminum, Mn/Al). These materials are combined to balance performance—nickel boosts energy density (for longer runtime), cobalt enhances stability, and manganese/aluminum reduces costs and improves safety. This mix makes the battery suitable for scenarios needing high energy and reliable operation, like consumer electronics or electric tools.

Are ternary cylindrical lithium-ion batteries the same as the ones used in everyday devices like laptops or electric toothbrushes?

Often, yes. Many laptops, electric toothbrushes, and even some e-bikes use small-capacity ternary cylindrical batteries (e.g., 18650 or 21700 models). The core technology is consistent—only the number of cells and module design differ to match the device’s power needs (e.g., a laptop uses multiple cells in series, while a toothbrush uses one or two).

Why do ternary cylindrical lithium-ion batteries have standard sizes (like 18650, 21700)? What do these numbers mean?

Standard sizes are designed for mass production and easy assembly. The numbers represent the battery’s dimensions: the first two digits are the diameter (in mm), and the last three are the height (in mm). For example, 18650 means 18mm in diameter and 65mm in height; 21700 means 21mm in diameter and 70mm in height. Standardization helps manufacturers reduce costs and ensures compatibility across devices.

Do ternary cylindrical lithium-ion batteries have a "memory effect"? Do I need to fully discharge them before charging?

No, they have almost no memory effect. Unlike older nickel-cadmium batteries, you don’t need to fully discharge them before charging. In fact, frequent deep discharges (draining to 0%) can shorten their lifespan. It’s better to charge them when the power drops to 20%–30% and stop charging at 80%–90% for daily use—this balances runtime and battery longevity.

How should I store ternary cylindrical lithium-ion batteries if I won’t use them for a long time?

Store them in a cool, dry place (ideally 10℃–25℃, away from direct sunlight or heat sources). Before storage, charge the battery to 40%–60% of its capacity—this prevents over-discharging (which damages cells) or overcharging (which causes capacity loss). Avoid storing them in fully charged or fully discharged states for more than 1 month.

Are ternary cylindrical lithium-ion batteries safe? What should I avoid to prevent risks like overheating?

They are safe when used correctly, but avoid these risks:

How long do ternary cylindrical lithium-ion batteries usually last? When should I replace them?

Their lifespan depends on usage frequency, typically 300–500 charge-discharge cycles (a cycle = full charge + full discharge). For daily use (e.g., a phone battery), this translates to about 1–2 years. You should replace them when:

Can ternary cylindrical lithium-ion batteries be recycled? How are they properly disposed of?

Yes, they can be recycled. Do not throw them in regular trash—this risks environmental pollution or fire. Instead, take them to designated recycling points (e.g., electronic waste collection centers, brand stores with recycling programs). Recyclers extract valuable metals (like nickel and cobalt) from the cells, which are reused to make new batteries, reducing resource waste.

Why are ternary cylindrical lithium-ion batteries not commonly used in large electric vehicles (EVs) anymore?

While some entry-level EVs still use them, many mainstream EVs now prefer prismatic or pouch ternary batteries. This is because:

What’s the difference between ternary cylindrical lithium-ion batteries and lithium iron phosphate (LFP) cylindrical batteries?

The main difference is the cathode material: