What Are Lithium-Ion Batteries?
Lithium-ion is the most popular rechargeable battery chemistry used today. Lithium-ion batteries power the devices we use every day, like our mobile phones and electric vehicles.
Lithium-ion batteries, also known as li-ion batteries, consist of single or multiple lithium-ion cells.
What’s inside a lithium-ion battery cell?
- Electrodes: The positively and negatively charged ends of a cell, attached to the current collectors
- Anode: The negative electrode
- Cathode: The positive electrode
- Electrolyte: A liquid or gel that conducts electricity
- Current collectors: Conductive foils at each electrode of the battery that are connected to the terminals of the cell. The cell terminals transmit the electric current between the battery, the device, and the energy source that powers the battery.
- Separator: A porous polymeric film that separates the electrodes while enabling the exchange of lithium ions from one side to the other
How do lithium-ion batteries work?
In a lithium-ion battery cell, lithium ions (Li+) move between the cathode and anode internally. Electrons move in the opposite direction in the external circuit. This migration is the reason the battery powers the device — because it creates the electrical current.
While the battery is discharging, the anode releases lithium ions to the cathode, generating a flow of electrons that helps to power the relevant device.
When the battery is charging, the opposite occurs: lithium ions are released by the cathode and received by the anode.
What devices use lithium-ion batteries?
Batteries and cells are produced in a variety of chemistries and shapes, also known as formats. Lithium-ion batteries are used in a wide variety of applications ranging from wearable technology and mobile phones to satellites and electric buses.
Products powered by lithium-ion batteries require a range of specifications for optimum and safe performance with respect to energy, power, and life span.
Why are lithium-ion batteries so popular?
Lithium-ion batteries offer a number of benefits that make them well-suited to energy storage for a wide range of applications. Some of these benefits include:
- High energy density: Lithium-ion batteries can store a large amount of energy in a small volume and can be very light.
- High power density: Lithium-ion batteries have the capability to support very high power demands.
- Rechargeability: Lithium-ion batteries can be charged hundreds to thousands of times.
- Portability: The combination of high energy density and rechargeability makes lithium-ion batteries useful for powering portable devices.
These same qualities are also why lithium-ion batteries can pose fire and safety risks if not handled properly.
Where should I look for lithium-ion batteries?
Use UL Research Institutes’ household checklist to identify battery-powered devices throughout your home.
Lithium-ion batteries can show up in almost every room in the house. If an object runs on electricity and is cordless or rechargeable, there is a high chance it is powered by lithium-ion. Use this checklist to take stock of the li-ion battery-powered objects in your life so that you can handle them with care and dispose of them properly.
In the bathroom, look for…
- Electric toothbrushes
- Electric razors and trimmers
- Cordless hair tools (blow-dryer, curling iron, straightener, etc.)
- Cordless skin tools (mask, exfoliator, etc.)
- Digital scales
- Pulse oximeters
- Blood pressure monitors
- Rechargeable medical equipment
- Towel warmers
- Cordless clothes steamers
In the bedroom, look for…
- Cordless air quality machines (purifier, humidifier, dehumidifier, etc.)
- Cordless lighting (lamps, string lights, night light, reading light, etc.)
- Heated blankets
- Heating pads
- Digital alarm clocks
- Cordless sound machines
- E-readers
In the garage, look for…
- Electric vehicles (cars, trucks, SUVs)
- Electric bikes
- Electric scooters
- Electric wheelchairs
- Cordless power tools (saw, drill, sander, etc.)
- Cordless yard tools (leaf blower, hedge trimmer, string trimmer, etc.)
- Smart home security (locks, doorbells, cameras, etc.)
- Cordless and wireless pet supplies (fence, collar, clippers, etc.)
- Cordless holiday and yard decor
- Flashlights or headlamps
- Portable grills
- Portable fans
- Portable space heaters
- Drones
In the kitchen, look for…
- Smoke detectors
- Carbon monoxide detectors
- Cordless appliances (food processer, blender, mixer, etc.)
- Digital food scales
- Digital food thermometers
- Digital thermostats
- Cordless or robot vacuums
In the living room, look for….
- Remote controls
- Game controllers
- VR headsets
- Bluetooth speakers
- Remote-controlled toys
- Electric lighters
- Wireless routers
In your bag, look for…
- Laptops
- Tablets
- Cell phones
- Portable chargers
- Digital cameras
- Smart watches
- Smart rings
- E-cigarettes
- Personal safety alarms
- Cordless music players
- Bluetooth headphones
About UL Research Institutes
UL Research Institutes is an independent, nonprofit organization advancing public safety through scientific discovery. Since 1894, we’ve worked to build a safer, more secure, and sustainable future. Our researchers investigate critical risks — from fire safety and chemicals to energy storage, digital privacy, and emerging materials — through rigorous, unbiased science. We collaborate globally and share our findings openly to inform standards, policy, and public understanding, while also cultivating the next generation of safety scientists through innovative educational programs and research experiences. As part of a broader safety ecosystem, we operate independently from UL Standards & Engagement and UL Solutions, while contributing to a shared mission: working for a safer world. Discover more at UL.org.
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