LiFePO4 vs Lithium-Ion
Both are lithium-ion. The difference is the cathode - iron phosphate versus nickel-cobalt chemistries - and that difference decides lifespan, safety and the jobs each chemistry should be doing.
The comparison starts with a naming problem: LiFePO4 is a lithium-ion battery, so 'LiFePO4 vs lithium-ion' really means iron-phosphate chemistry against the nickel-manganese-cobalt (NMC) and nickel-cobalt-aluminium (NCA) chemistries that dominate phones, laptops and most EVs. Those chemistries exist because they pack the most energy into the least weight and volume. LiFePO4 exists because, for a large class of jobs, that is the wrong thing to optimise.
Cycle life is the widest gap. NMC-class cells are typically rated in the hundreds to roughly a thousand full cycles before they fade to 80% of original capacity. LiFePO4 packs in stationary and motive service are rated in the thousands - the storage datasheets in this manufacturer's range state 6,000 cycles or more at 80% depth of discharge. For a battery that cycles daily, that is the difference between replacing the bank in year three and planning around it in year twelve.
Safety is the second gap. Cobalt- and nickel-rich cathodes can release oxygen as they break down under abuse, feeding thermal runaway; the iron-phosphate cathode's strong phosphorus-oxygen bond holds its oxygen far more stubbornly, so LiFePO4 tolerates overcharge, heat and mechanical abuse with a much wider margin. Energy density is where the nickel chemistries win honestly: per kilogram and per litre they store more, which is why aircraft, phones and long-range EVs accept their trade-offs. Cost follows the materials: iron and phosphate are cheap and abundant; nickel and cobalt are neither.
