Battery Chemistry

The two chemistries that matter for home storage

Nearly all home batteries sold in Australia today use one of two lithium-ion chemistries. The choice between them reflects different engineering trade-offs.

LFP - Lithium Iron Phosphate (LiFePO₄)

LFP cells use an iron phosphate cathode. The chemistry is intrinsically stable - LFP cells don’t enter thermal runaway as readily as NMC, and there’s no oxygen release if the cell is damaged or overcharged. This makes LFP significantly safer in residential applications.

The trade-offs: LFP has lower energy density (about 90–160 Wh/kg vs NMC’s 150–220 Wh/kg), so an LFP battery is larger and heavier for the same capacity. It also has a flatter discharge curve, which makes accurate state-of-charge estimation harder - the BMS needs more sophisticated algorithms.

For home batteries, none of these trade-offs matter much. A heavier battery bolted to a wall is still a battery on a wall. The advantages - cycle life of 6,000–10,000+ cycles, better high-temperature tolerance, and reduced fire risk - are decisive.

Products using LFP: Tesla Powerwall 3, Sungrow SBR series, BYD Battery-Box, Alpha ESS Storion.

NMC - Nickel Manganese Cobalt

NMC cells pack more energy into less space and weight, which is why they’re still common in long-range EVs where every kilogram costs range. Older residential batteries (some 2015–2020 models) used NMC.

The problem is stability. NMC cells can enter thermal runaway more readily at high temperatures or if overcharged, which requires more sophisticated thermal management. Cycle life is lower - typically 2,000–4,000 cycles at 80% DoD vs LFP’s 6,000+.

For stationary storage in Australian conditions - hot summers, outdoor enclosures, daily cycling - NMC is a worse fit than LFP. Most manufacturers have moved to LFP for residential products.

What this means practically

If you’re comparing two batteries and one is LFP and one is NMC, the LFP product will almost certainly last longer in Australian conditions. The warranty cycle count is the clearest signal: if it’s below 5,000 cycles, check which chemistry it’s using.

Older NMC batteries installed before 2020 should be checked for any manufacturer service bulletins - particularly those installed in hot, poorly ventilated locations. The ACCC has issued several product safety notices for early residential battery products.