The invention discloses a mixed-valence iron-based
fluoride positive
electrode material and a preparation method thereof. The method comprises the steps that 1, newly-prepared FeF3.3H2O is weighed, heated to 180-220 DEG C under the
argon protection condition and then subjected to heat preservation for 2 h; raising the temperature to 400-420 DEG C again, keeping the temperature for 2 hours, and naturally cooling to
room temperature to obtain a precursor; 2, mixing the precursor with
oxalic acid, and carrying out high-speed ball milling and
drying treatment; and 3, putting the mixture of the precursor and
oxalic acid into a high-temperature reactor, introducing
hydrogen-
argon mixed gas, heating to 420 DEG C, keeping the temperature for 10-30 minutes, stopping introducing the
hydrogen-
argon mixed gas, introducing argon again, and quickly cooling to
room temperature to obtain the mixed-valence iron-based
fluoride positive
electrode material of which the structural general formula is FexF3,wherein x is more than 1 and less than or equal to 1.2. The preparation method of the positive
electrode material is good in flexibility, the content of
ferrous iron in the positive
electrode material can be controlled by adjusting the addition amount of
oxalic acid and the reaction time, the technological method is simple, the operation labor intensity is low, and the requirement of large-scaleindustrial production is met.