Two chemistries, one job
Almost every home battery sold in Australia is a lithium-ion battery, but the term covers several different cell chemistries. Two dominate the residential market. The first is lithium iron phosphate, written as LFP or LiFePO4, which uses an iron-phosphate cathode. The second is nickel manganese cobalt oxide, written as NMC (sometimes NCM), which uses a layered cathode of those three metals. Both store and release energy by shuttling lithium ions between electrodes; the difference lies in the cathode material, and that single difference cascades into almost every property a homeowner cares about.
Energy density and physical size
Energy density describes how much energy a cell stores per unit of weight or volume. NMC has the clear advantage here. Its layered structure and higher nominal cell voltage (around 3.6–3.7 volts, against roughly 3.2 volts for LFP) let it pack more energy into a smaller, lighter package. Comparative figures put typical NMC cell energy density well above that of LFP — broadly in the order of 180–250 watt-hours per kilogram for NMC against roughly 120–180 for LFP — which is why NMC has long been favoured for electric vehicles and other uses where space and weight are tightly constrained.
For a wall-mounted or floor-standing home battery, this matters far less. A few extra kilograms or centimetres rarely changes a fixed installation, so the density penalty of LFP is mostly cosmetic in a residential setting.
Cycle life and depth of discharge
Cycle life is where LFP pulls ahead. A cycle is one full charge and discharge, and a home battery may complete one or more each day for a decade or more. LFP cells generally tolerate more cycles before their capacity fades meaningfully, and they handle deep daily discharge well, which suits the typical solar-storage pattern of charging through the day and discharging each evening. NMC cells are durable but tend to be specified for fewer deep cycles at an equivalent depth of discharge. Manufacturers state usable capacity and warranty terms differently, so always compare the warranted throughput (often given in cycles or megawatt-hours) rather than headline numbers.
Thermal stability and safety
This is the most important practical difference. The iron-phosphate cathode in LFP is held together by strong phosphorus-oxygen bonds that resist breaking down when heated, so the cell is far less likely to release oxygen and enter thermal runaway (a self-sustaining overheating reaction). NMC cathodes are less thermally stable, and that tendency generally increases as the nickel content rises.
A peer-reviewed study comparing cell chemistries ranked thermal-runaway danger as LCO > NCA > NCM811 >> LFP, with LFP both reaching far lower peak temperatures and releasing heat much more slowly during abuse testing. In that work the LFP cells peaked at around 240°C, against roughly 460–550°C for the nickel- and cobalt-rich chemistries, a temperature low enough that the cell did not ignite. In plain terms, an LFP cell that is damaged or faulty is much less likely to catch fire, and any event is generally less severe. Both chemistries can be safe when properly engineered, installed, and managed by a battery management system, but LFP's chemistry provides an extra margin that is valuable inside a home.
Temperature behaviour
Lithium-ion cells of any chemistry lose performance in the cold, as the electrolyte thickens and ions move more slowly. NMC tends to retain a little more usable capacity in very cold conditions, which is one reason it remains popular for cold-climate electric vehicles. LFP, in turn, copes well with sustained warmth. In most populated parts of Australia, where extreme cold is uncommon, neither chemistry's temperature quirks are decisive, though batteries should still be sited out of direct sun and harsh heat.
Cost
LFP avoids cobalt and nickel, two relatively expensive and supply-constrained metals, which has helped drive its cell cost below that of NMC at scale. Falling LFP cell prices are a major reason the chemistry has spread so quickly into stationary storage. Final installed prices depend on the whole system and the installer, not the cells alone, so treat chemistry as one input among many.
Why most new home batteries are LFP
The International Energy Agency notes that energy density is far less critical for stationary storage than for vehicles, and that lower cost, longer life, and lower flammability have driven a strong shift to LFP. The agency reports that LFP made up around 80 per cent of new battery-storage capacity in 2023, and that share has continued to grow. NMC still appears in some home products, particularly compact or older designs, but the trend across new residential storage is firmly towards LFP.
For a buyer, the takeaway is straightforward. Confirm the chemistry, check that the product appears on the Clean Energy Council approved battery list and meets the relevant Australian safety standards, and compare warranties on a like-for-like basis. To understand the broader system context, see how storage interacts with panels in AC vs DC solar, and use the solar system size calculator to estimate the capacity your home is likely to need.