LiFePO4n

LiFePO4n is a term occasionally found in battery literature to describe lithium iron phosphate–based materials that depart from the exact LiFePO4 stoichiometry or exist as nanostructured or doped variants intended to improve performance. It is not a standard chemical designation, and its precise meaning varies by source; many authors simply refer to LiFePO4 or to related doped/nanostructured derivatives when discussing these materials. The underlying chemistry generally centers on LiFePO4, a cathode material well known for safety and stability.

The base material, LiFePO4, crystallizes in an olivine structure and features Fe2+/Fe3+ redox, with a theoretical capacity of about 170 mAh/g and an average operating voltage near 3.2–3.4 V versus Li+/Li. Owing to its high thermal stability, non-flammability of the phosphate framework, and long cycle life, LiFePO4 has become a common cathode choice for safe, large-format lithium-ion cells.

To realize LiFePO4n-like performance, researchers commonly apply strategies such as carbon coating, nanosizing, and doping to improve electronic conductivity and lithium diffusion. Variants may involve non-stoichiometric lithium content (for example LiFePO4−δ), nitrogen or carbon dopants, or minor metal substitutions, all aimed at enhancing rate capability and cycle life. Synthesis methods include solid-state routes, hydrothermal or solvothermal processes, and carbothermal reduction.

Applications span electric vehicles, grid storage, and portable electronics where safety, stability, and longevity are prioritized over peak energy density. Limitations include relatively lower energy density compared with nickel- or cobalt-containing cathodes and sensitivity of performance to particle size, coating quality, and synthesis control. LiFePO4n variants seek to balance stability with improved electrochemical performance.