Reaching the full capacity of the electrode material Li3FeF6 by decreasing the particle size to nanoscale

► Nanometric lithium iron fluoride has been obtained. ► 20 nm particles form 200 nm diameter spherical-like agglomerates. ► Lithium insertion depends on size of the agglomerates. ► Breaking of agglomerates by ball milling reduces the size below 200 nm. ► Full specific capacity is obtained in ball milled samples.