High manganese polycrystalline anode material, preparation method thereof and dynamic lithium ion battery
Provided are a high manganese polycrystalline anode material, preparation method thereof and dynamic lithium ion battery. The general formula of the high manganese polycrystalline anode material is LiwMnx(CoNi)yOz, wherein x=0.4-2.0, y=0.1-0.6, x+y<2, z≧2, and w≧1. The weight of Mn is not less than 40% of the weight of LiwMnx(CoNi)yOz, and the particle size thereof is 7-20 microns. The high manganese polycrystalline anode material has more than two lattice structures selected from LiMn 2 O 4 , LiCO n (NiMn) 1-n O 2 , LiNi 0.8 Co 0.2 O 2 , LiCoO 2 , LiNi n Mn 1-n O 2 , LiMn 2n Ni 2(1-n) O 4 and LiNiO 2 , which are in mixed state or intergrowth state, wherein n<1. The specific energy of the anode material is more than 155 Wh/K, the conservation rate of the capacity is not less than 80% after 500 charging and discharging circles when the charging and discharging multiplying dynamic is 1C and at 55° C., and at 25° C., its cycle life is not less than 1000 times and the conservation rate of the capacity is more than 80%. The processability of the anode material is good.
1. A preparation method of high manganese polycrystalline anode material, comprising the steps of: (a) preparing a precursor: dispersing 0.3˜1.2 mol of Li element in Li 2 CO 3 , LiAc or LiOH into 200˜300 ml aqueous colloid of 2˜5% polyethylene glycol to form a colloid in which a first preset speed is 10˜60 rin/min and a first preset time is 50˜120 min; adding cobalt-nickel-manganese compound into said colloid, where a molar ratio of Mn to Ni+Co is 0.4˜2.0:0.01˜0.6, a second preset speed is 50˜60 rin/min and a second preset time is 10˜30 min; drying under 150˜600° C. for 2˜15 hours to obtain said precursor which has a crystalline form and contains Li and Co—Ni—Mn, where a third preset speed is 1500˜3000 rin/min and a third preset time is 2˜30 min; (b) forming a single crystalline structure: heating said precursor under 750˜1000° C. for 4˜15 hours for allowing agglomeration of said precursor; cooling; breaking until a particle size D D50=7˜20 micron is obtained; obtaining a single crystal compound of LiMn 2 O 4 , LiCo n (NiMn) 1-n O 2 , LiNi 0.8 Co 0.2 O 2 , LiCoO 2 , LiNi n Mn 1-n O 2 , LiMn 2n Ni 2(1-n) O 4 or LiNiO 2 , where n<1; (c) forming a polycrystalline structure: mixing two or more said single crystal compounds to form a mixture, where a content of Mn constitutes 60˜90% of a total molar volume of Co+Ni+Mn, a fourth preset speed is 100˜150 rin/min and a fourth preset time is 5˜20 min; dissolving 0.01˜0.1 mol soluble salt containing one or more elements from the group consisting of Al, Si, Ti, Fe, Zr Mg and Cr into 100˜300 ml 30˜60% ethanol solution; adding said mixture; mixing under a fifth preset speed of 60˜100 rin/min and a fifth preset time of 30˜60 min; drying under 100˜200° C. for 2˜10 hours; heating to 300˜850° C. at a heating rate of 50˜100° C./hr for activation for 2˜10 hours to obtain said polycrystalline structure having a mixed state or an intergrowth state.
2. The preparation method of high manganese polycrystalline anode material, as recited in claim 1 , wherein said intergrowth state of said polycrystalline structure is crushed.
3. The preparation method of high manganese polycrystalline anode material, as recited in claim 1 , wherein said polycrystalline structure having said mixed state and said intergrowth state is crushed with a rotational speed of 1500˜3000 rin/min for 2˜5 min.
4. The preparation method of high manganese polycrystalline anode material, as recited in claim 3 , wherein said cobalt-nickel-manganese compound is hydroxy, oxalate or carbonate compound.
5. The preparation method of high manganese polycrystalline anode material, as recited in claim 4 , said precursor carries out agglomeration under 750˜1000° C. for 4˜15 hours, which is then cooled naturally.