▎ 摘　　要

NOVELTY - Polyanionic compound (I), is new and prepared by using carbon source, source A, vanadium source, phosphorus source, source B and source D as raw materials, adopting a sol gel method to obtain precursor of a polyanionic compound, and sintering the precursor to obtain polyanionic compound USE - The polyanionic compound is used as an anode material, preferably anode material for a secondary battery (e.g. at least one of lithium secondary battery, sodium secondary battery, zinc secondary battery, magnesium secondary battery, aluminum secondary battery and potassium secondary battery, preferably lithium secondary battery, sodium secondary battery or zinc secondary battery, more preferably at least one of aqueous secondary battery and non-aqueous secondary battery) (all claimed). ADVANTAGE - The polyanionic compound has good electrochemical performance e.g. rate performance and cycle stability. The method has simple process. DETAILED DESCRIPTION - Polyanionic compound of formula (A3V2-mBm(PO4)3-nDn/C) (I), is new. The doping amount of cation B is m = 0-0.5, preferably 0.01-0.3, more preferably 0.2, and the doping amount of anion D is n = 0-0.16, preferably 0.01-0.15, more preferably 0.12. A = at least one of lithium, sodium and potassium, preferably lithium or sodium; B = at least one of calcium, magnesium, titanium, aluminum, iron, bismuth, strontium, manganese, cobalt, scandium, technetium, zinc, palladium, molybdenum, tin, antimony, arsenic, selenium and barium, preferably at least one of aluminum, magnesium, titanium and copper; D = at least one of fluorine, chlorine, bromine and iodine, preferably chlorine. The preparation of the polyanionic compound is as follows: preparing carbon source, source A, vanadium source, phosphorus source, source B and source D by a sol gel method to obtain the precursor of the polyanionic compound, sintering the precursor, where the source A is at least one of lithium source, sodium source and potassium source. The lithium source is at least one of lithium hydroxide, lithium carbonate, lithium hypophosphite, lithium lactate, lithium amide, lithium tetrafluoroborate and lithium perchlorate, preferably lithium hydroxide. The sodium source is at least one of sodium carbonate, sodium hydroxide, sodium dihydrogen phosphate, sodium oxalate, sodium citrate, sodium phosphate, disodium hydrogen phosphate, sodium lactate, sodium bicarbonate, sodium chloride, sodium dodecyl sulfonate, sodium sulfate and sodium nitrate, preferably at least one of sodium hydroxide, sodium carbonate and sodium bicarbonate. The potassium source is at least one of potassium hydroxide, potassium carbonate, potassium perchlorate, potassium chloride, potassium sulfate, potassium nitrate and potassium ferricyanide, preferably potassium hydroxide. The vanadium source is at least one of ammonium metavanadate, vanadium pentoxide, vanadyl acetylacetonate, vanadyl sulfate, vanadium dioxide and vanadium trioxide, preferably at least one of ammonium metavanadate, vanadium pentoxide and vanadyl sulfate. The source B is at least one of salts, hydroxides and nitrides containing element B, preferably at least one of an aluminum source and a magnesium source, where the salt containing element B is at least one of sulfate, hydrochloride, nitrate, phosphate and thiosulfate containing element B. The aluminum source is at least one of aluminum hydroxide, aluminum chloride, aluminum sulfate and aluminum nitrate. The magnesium source is at least one of magnesium hydroxide, magnesium chloride, magnesium sulfate, magnesium nitride, magnesium thiosulfate and magnesium hydrogen phosphate, preferably magnesium chloride. The phosphorus source is at least one of ammonium dihydrogen phosphate, diammonium hydrogen phosphate, phosphoric acid, sodium dihydrogen phosphate, ammonium phosphate, disodium hydrogen phosphate and phosphorus pentoxide, preferably ammonium dihydrogen phosphate. The carbon source is at least one of citric acid, glucose, sucrose, fructose and oxalic acid, preferably citric acid. The source D is compound containing element D composed of at least one of fluorine source, chlorine source, bromine source and iodine source. The fluorine source is at least one of potassium fluoride, sodium fluoride, ammonium fluoride, lithium fluoride and calcium fluoride. The chlorine source is at least one of potassium chloride, sodium chloride, ammonium chloride, magnesium chloride, lithium chloride and calcium chloride, preferably magnesium chloride. The bromine source is at least one of potassium bromide, sodium bromide, ammonium bromide, lithium bromide and calcium bromide. The iodine source is at least one of potassium iodide, sodium iodide, ammonium iodide, lithium iodide and calcium iodide, where the source B and D can be the same, and both are magnesium chloride. INDEPENDENT CLAIMS are also included for: (1) preparation of polyanionic compound; and (2) preparing secondary battery.