Quick answer
Lithium-Ion Battery A lithium-ion battery is a rechargeable battery that stores energy by moving lithium ions from the cathode to the anode when charging and back again when discharging. It is the family of chemistries behind nearly all new home solar batteries and grid battery projects.
"Lithium-ion" names the family; the cathode material, such as LFP or NMC, names the type.
Quick facts
The key facts about lithium-ion battery, with sources:
- Abbreviation
- Li-ion, LIB
- Anode
- Usually graphite or another carbon 1
- Cathode types
- LFP, NMC, NCA, LCO, LMO 1
- Two dominant types
- NMC (energy density) and LFP (safety) 1
- Share of new US grid batteries
- More than 90% in 2020 and 2021 1
- Typical life
- 10+ years and 1,000+ cycles, depending on use 1
- Disposal
- Never in household trash or recycling bins; large batteries go back through the installer or maker 5
Key takeaways
- Lithium-ion is a family of rechargeable batteries. The cathode material, such as LFP or NMC, names the type.
- Nearly all new home solar batteries use it, as do more than 90% of new US grid batteries in 2020–2021.
- Expect a life or warranty of 10+ years and 1,000+ cycles, depending on use.
- The main risk is thermal runaway. Listed systems, a BMS and code spacing manage it.
- Old or damaged units go back through the installer or maker, never in the trash.
What "lithium-ion" means
The name describes how the battery works. Lithium atoms that have lost an electron, called ions, shuttle between two electrodes. They never turn into metal, which is what sets lithium-ion apart from one-use lithium-metal cells.
The same family powers phones, laptops, electric cars and home batteries. The cells differ in size and in the cathode recipe. DOE lists five main cathode classes and notes that the anode is mostly graphite or another carbon, with lithium titanate used in some high-power or high-cycle uses 1.
Sources: [1]
How a lithium-ion battery works
Every lithium-ion cell has the same four parts, and the same back-and-forth that DOE calls a "rocking chair" design:
- Charging: lithium ions leave the cathode and travel through the electrolyte to the anode.
- The electrolyte, an organic liquid or polymer holding a lithium salt, carries the ions.
- The separator, a microporous polymer or ceramic sheet, keeps anode and cathode from touching and shorting.
- Discharging: ions return to the cathode, and electrons flow through your home's circuits to make the trip.
Cells are grouped in series and parallel into modules and packs, then wrapped with a battery management system and thermal controls to become a usable battery.
Sources: [1]
From cell to home battery
- Cell (anode, cathode, electrolyte, separator) → module (cells wired together)
- Modules → pack, with BMS and thermal controls 1
- Pack + inverter + safety parts → listed battery energy storage system
The lithium-ion family, by cathode
| Type | Cathode | What DOE says about it |
|---|---|---|
| LFP | Lithium iron phosphate | Chosen for safety; contains no cobalt or nickel; forecast to be the main chemistry by 2030 1 |
| NMC | Lithium nickel manganese cobalt oxide | Chosen for energy density; newer blends cut cobalt by adding nickel 1 |
| NCA | Lithium nickel cobalt aluminium oxide | Listed as a cathode class 1 |
| LCO | Lithium cobalt oxide | Listed as a cathode class 1 |
| LMO | Lithium manganese oxide | Listed as a cathode class 1 |
Example: three home lithium-ion batteries side by side
Figures copied from current data sheets. All three are lithium-ion; two name LFP.
| Battery | Chemistry stated | Energy | AC round trip | Warranty |
|---|---|---|---|---|
| Enphase IQ Battery 5P | LFP 6 | 5.0 kWh usable | 90% 6 | >60%, 15 yr or 6,000 cycles 6 |
| FranklinWH aPower 2 | LFP 9 | 15 kWh usable | 90% 9 | 15 yr or 60 MWh 9 |
| Tesla Powerwall 3 | Not stated 7 | 13.5 kWh nominal | 89% solar-battery-home 7 | 70% at 10 yr 8 |
The point: "lithium-ion" alone does not tell you much. Ask for the cathode type, usable kWh and warranty floor in writing.
Where lithium-ion is used, and why it took over home storage
Two reasons stand out in the federal sources. First, scale: electric-vehicle production drove down the cost of large lithium cells, and NREL notes lithium-ion prices fell more than 70% from 2010 to 2016.
Second, flexibility: DOE notes that a lithium-ion battery's power and energy rise together as it gets bigger, so one design can serve short, high-power jobs and multi-hour shifting.
For a home that means a wall-sized unit that can cover evening use, back up circuits in an outage and shift energy on a time-of-use rate. Lithium-ion batteries are typically used for durations of 10 hours or less, which suits a daily solar cycle.
On the grid, the EIA says most US utility-scale battery systems use lithium-ion, for its high cycle efficiency and fast response 3.
Strengths and limits
What it does well
- Recharges thousands of times; warranties are written in cycles as well as years.
- Efficient: current home units publish about 89%–90% AC round-trip efficiency.
- Packaged with management electronics, so there is nothing for the owner to maintain.
- Compact and quiet; Enphase lists under 30 dBA at 1 m for the IQ Battery 5P 6.
Where it falls short
- Can enter thermal runaway if damaged or badly managed, which is why listing and fire testing exist.
- Capacity fades with age and use.
- Cobalt, nickel and lithium are largely sourced abroad, DOE notes; LFP avoids the first two.
Limits to know about
Ageing. DOE says keeping lithium-ion cells at a high charge for long periods is one of the biggest drivers of capacity fade 1. Cycling wears them too.
Temperature. Cells like mild conditions. Enphase lists a best range of 0°C to 30°C (32°F to 86°F) and allows charging only from –20°C to 50°C 6. Tesla notes output may be cut above 40°C (104°F) 7.
Duration. Lithium-ion is used mostly for jobs of 10 hours or less 2. Multi-day backup needs more units or another source.
What drives cost and lifespan
The cells are the biggest single part, but not the whole bill. NLR splits home battery cost into the pack, the battery inverter, other hardware, labor, supply chain, permits and interconnection, sales and overhead, and profit 4. HyreSolar does not print prices without dated quotes.
Materials matter for long-run cost. DOE names cobalt, nickel and lithium as the most critical elements. It notes LFP has fewer supply limits since it uses no cobalt or nickel 1.
Lifespan. DOE: 10+ years and 1,000+ cycles, depending on use 1. NLR models 15 years at about one cycle a day, with possible replacement in that time 4. Your warranty sets the firm terms.
How a lithium-ion home battery gets installed
A licensed electrician or installer does all the work. The usual path:
- Choose a listed system and a code-allowed spot, such as a garage or outside wall.
- File plans with the building department; many ask for the UL 9540 listing.
- Mount, wire and connect it to the panel, solar and a backup switch if needed.
- Pass inspection and get the utility's okay if it ties to the grid.
- Commission it: firmware, reserve setting and monitoring.
Care and end of life
Day to day, there is little to do. Keep the area clear and dry, keep the system online for updates, and watch the app for alerts. Tesla expects owners to provide internet for Powerwall 3 7.
At end of life, the EPA says lithium-ion batteries must not go in household trash or recycling bins. For large batteries, it says to contact the maker or the company that installed it for options 5. See our page on solar panel recycling for the wider system.
Warning signs and when to call a pro
- Swelling, bulging or a cracked case.
- Hissing, popping, smoke, or a sharp or sweet chemical smell.
- The unit is much hotter than usual or shows over-temperature alerts.
- Damage from a flood, fire, car impact or fall.
- Leave the area and call 911 for smoke or fire. For anything else, call the installer and do not touch it.
Safety rule
A damaged lithium-ion battery can catch fire hours later. Do not move it, open it or put it in the trash. Call the installer.
Standards and codes for lithium-ion home batteries
Product listings. UL 1973 covers the battery and UL 9540 the whole system. UL Standards & Engagement published the third edition of UL 9540 on 28 June 2023 10. UL 9540A is the fire test that measures whether thermal runaway spreads.
Install rules. The 2021 IRC R328 and NFPA 855 Chapter 15 cap units at 20 kWh each. They require 3 feet between units unless UL 9540A data shows less is safe.
Totals are capped at 40 kWh in utility rooms and 80 kWh in garages or outdoors 11. Your local adopted edition rules; South Carolina enforces the 2021 codes 13.
Waste. The EPA recommends businesses manage used lithium-ion batteries under the federal universal waste rules, 40 CFR Part 273 5.
Lithium-ion vs other battery terms
| Term | What it is | How it relates |
|---|---|---|
| Lithium-ion | The chemistry family | — |
| LFP | Lithium-ion with an iron phosphate cathode | One member, chosen for safety 1 |
| NMC | Lithium-ion with a nickel-manganese-cobalt cathode | One member, chosen for energy density 1 |
| Lead-acid | An older rechargeable type | Far fewer cycles at deep discharge; see depth of discharge |
| Solar battery | The finished home product | Usually lithium-ion inside |
Misconceptions
- Myth All lithium-ion batteries are the same.
- Reality Cathode type changes safety, energy density and supply chain. DOE pairs NMC with energy density and LFP with safety 1.
- Myth Lithium-ion batteries need regular maintenance.
- Reality Home units are sealed and managed by a BMS. Owners keep them clear, online and watched.
- Myth A dead battery can go out with the trash.
- Reality The EPA says never put lithium-ion batteries in household trash or recycling 5.
Lithium-ion batteries in SC, GA and VA
Chemistry rules are national, but the Southeast brings heat and storms. Heat can derate output on a sun-facing wall 7.
South Carolina customers averaged nearly 53 hours without power in 2024, the most of any state, mostly from Hurricane Helene 12. SC enforces the 2021 building codes with the R328 storage rules 13. In Georgia and Virginia, ask your county which code edition applies.
What to check on a home battery quote
Look for the chemistry row. The Enphase IQ Battery 5P data sheet states lithium iron phosphate (LFP). The Tesla Powerwall 3 data sheet lists no chemistry at all. If the type matters to you, ask the installer to show it in writing.
Then check the listings: UL 1973 for the battery and UL 9540 for the complete system appear on both data sheets. Our LFP vs NMC guide explains why the safety-test wording differs between makers.
Next steps
- Battery sizing toolSize kWh and kW to your loads
- Compare home battery storage
- Solar battery statistics
Questions about lithium-ion battery
Is LFP a lithium-ion battery?
Yes. LFP, lithium iron phosphate, is a lithium-ion battery with an iron phosphate cathode. "Lithium-ion" is the family; LFP and NMC are members of it. DOE describes NMC as chosen for energy density and LFP for safety, and both are common in home storage.
Is a lithium-ion battery the same as a lithium battery?
In everyday use, usually. Strictly, "lithium battery" can also mean non-rechargeable lithium-metal cells, so data sheets use lithium-ion or name the chemistry. For a home solar battery, the two words almost always mean the same rechargeable lithium-ion pack.
How long do lithium-ion home batteries last?
DOE says lithium-ion batteries often have a life or warrantied life of 10+ years and 1,000+ cycles, depending on how they are cycled and controlled. NLR models home batteries over 15 years. Read your warranty for the exact years, cycles and retained capacity.
Are lithium-ion home batteries safe?
Listed systems installed to code are designed to contain failures: a management system cuts off before limits are exceeded, and the system is listed to UL 9540 with fire-test data from UL 9540A. Installation spacing and location rules in the residential code add a further margin.
What is thermal runaway?
Thermal runaway is when a damaged or overheated cell starts making its own heat faster than it can shed it, which can spread to nearby cells and cause fire. The BMS prevents the usual triggers. UL 9540A testing shows whether a failure spreads beyond one cell.
How do I dispose of an old lithium-ion home battery?
Do not put it in the trash or curbside recycling. The EPA says to contact the maker or the company that installed a large lithium-ion battery for options. Your installer should remove it. Damaged units need extra care in transport.
Why do some data sheets not name the chemistry?
Makers are not required to print it. The Tesla Powerwall 3 data sheet, for example, lists no chemistry, while Enphase and FranklinWH both state LFP. If the chemistry matters to your choice, ask the installer to confirm it in writing.
Does cold weather hurt a lithium-ion battery?
Cold slows it and can block charging. Enphase allows the IQ Battery 5P to charge only from –20°C (–4°F) and lists 0°C to 30°C as its best range. The BMS stops charging outside safe limits, so a cold garage can delay a refill until it warms up.
Sources
- US DOE Office of Electricity, Lithium-ion Batteries Technology Strategy Assessment (DOE/OE-0031, July 2023), retrieved .
- NREL, Grid-Scale Battery Storage: Frequently Asked Questions (NREL/TP-6A20-74426, 2019), retrieved .
- US EIA, Energy storage for electricity generation, retrieved .
- National Laboratory of the Rockies (NLR, formerly NREL), Annual Technology Baseline 2024: Residential Battery Storage, retrieved .
- US EPA, Used Lithium-Ion Batteries, retrieved .
- Enphase Energy, IQ Battery 5P data sheet (DSH-00010-11.0-EN-2025-05-06), retrieved .
- Tesla, Powerwall 3 Datasheet (2024), retrieved .
- Tesla, Powerwall Limited Warranty (USA), effective 21 August 2023, retrieved .
- FranklinWH, aPower 2 data sheet (2025), retrieved .
- UL Standards & Engagement, ULSE publishes third edition of UL 9540 (28 June 2023), retrieved .
- UL, 2021 Residential ESS Requirements (IRC R328 and NFPA 855 Chapter 15 summary, 2021), retrieved .
- US EIA, Today in Energy: Hurricanes in 2024 led to the most hours without power in 10 years, retrieved .
- SC Building Codes Council, code adoption, retrieved .
Expert review
Written by the HyreSolar Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: Mechanism, cathode classes, deployment share, ageing and life from the DOE lithium-ion assessment; price trend from NREL; grid use from EIA; cost structure from the NLR ATB.
Disposal from EPA; chemistry, efficiency and warranties read from the Enphase, FranklinWH and Tesla data sheets and Tesla US warranty; code limits from UL's IRC R328 / NFPA 855 summary.
No cell-level energy-density or thermal-runaway temperature is published because no primary source for home products supports one.
Suggest a correction. We fix errors and say what changed.