TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The metal-containing solution is made of elements selected from I and II group elements, group III, IV, V, VI, VII, VIII, IX, X, XI or XII transition metal, XIII, XIV, XV, XVI, XVII or XVIII group elements, lanthanide or their mixture. The ammonium cation containing compound is ammonium hydroxide, ammonium sulfate, ammonium nitrate or their mixture. The lithium-containing compound has general formulae (I-VII). LiaNixCoyMnzM1-x-y-zO2Qe LiaCo1-x-yZrxMyO2Qe LiaMn1-xMxO2Qe LiaMn2-xMxO4Qe LiaMn2-xMxO4Qe Li4+aTi4-xMxO12Qe LiMxPO4Qe In formula (I),M=B, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo or W;Q=halogen or S;a=1.0-1.2;x=0.0-0.95;y, z=0.0-0.7;1-x-y-z=0.0-0.3; ande=0.0-0.1.In formula (II),M=B, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo or W;Q=halogen or S;a=1.0-1.2;x=0.0-0.05;y=0.0-0.1;x+y=0.0-0.1; ande=0.0-0.1.In formula (III),M=B, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo or W;Q=halogen or S;a=1.0-1.2;x=0.0-0.5; ande=0.0-0.1.In formula (IV),M=B, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo or W;Q=halogen or S;a=1.0-1.3;x=0.0-0.2; ande=0.0-0.1.In formula (V),M=B, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo or W;Q=halogen or S;a=1.0-1.3;x=0.3-0.7; ande=0.0-0.1.In formula (VI),M=B, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo or W;Q=halogen or S; anda, x and e=0.0-0.1.In formula (VII),M=B, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo or W;Q=halogen or S;a, x=0.0-0.1; ande=0.0-0.02.The fluorine-containing solution contains ammonium fluoride, hydrogen fluoride or their mixture. The lithium secondary battery includes a coating compound layer, where the coating compound is selected from metal fluoride, metal oxyfluoride, metal oxide, ammonium metal fluoride or their mixture. The metal fluoride is made of lithium fluoride, sodium fluoride, potassium fluoride, magnesium difluoride, calcium fluoride, copper fluoride, cadmium fluoride, iron fluoride, manganese fluoride, nickel fluoride, lead fluoride, tin fluoride, strontium fluoride, xenon fluoride, zinc fluoride, aluminum fluoride, boron fluoride, bismuth fluoride, cerium fluoride, chromium fluoride, indium fluoride, lanthanum fluoride, neodymium trifluoride, vanadium oxyfluoride, yttrium fluoride, germanium fluoride, hafnium fluoride, silicon fluoride, titanium fluoride, vanadium fluoride, zirconium fluoride, niobium fluoride, antimony fluoride, tantalum fluoride, molybdenum fluoride, sulfur hexafluoride, tungsten hexafluoride, rhenium hexafluoride or their mixture. The metal oxyfluoride is oxyfluoride of group III, IV, V, VI, VII, VIII or IX transition metal, XIII, XIV or XV group elements, lanthanide or their mixture. The metal oxide is oxide of magnesium, calcium, strontium, boron, aluminum, yttrium, zirconium, molybdenum, tungsten, chromium, iron, cobalt, nickel, zinc, gallium, germanium, indium, tin, bismuth, phosphorus or their mixture. The ammonium metal fluoride has general formula (VIII), (NH4)xMFyM=group III, IV, V, VI, VII, VIII or IX transition metal, XIII, XIV or XV group elements, lanthanide or their mixture;x=1-10; andy=2-16.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compounds: The organic acid is citric acid, glycolic acid or their mixture.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The chelating agent is made of ammonium cation containing compound, organic acid, polyelectrolyte or their mixture, where the polyelectrolyte is selected from poly(sodium styrene sulfonate), polypeptide or polyacrylic acid or their mixture.