US-12623906-B2 - Preparation method of multiple carbon-coated high-compaction lithium iron manganese phosphate

US12623906B2US 12623906 B2US12623906 B2US 12623906B2US-12623906-B2

Abstract

The present disclosure belongs to the technical field of lithium battery cathode materials, and discloses a preparation method of multiple carbon-coated high-compaction lithium iron manganese phosphate, comprising the following steps: (1) synthesizing a carbon and vanadium co-doped ferromanganese phosphate precursor through a co-precipitation method, sintering, and removing crystal water to obtain an anhydrous ferromanganese phosphate precursor; (2) adding lithium phosphate, a supplemental phosphorus source, an organic carbon source, a dopant and deionized water, and performing ball milling, wet sanding, spray drying and sintering to obtain an intermediate material; and (3) adding deionized water and the organic carbon source, then performing ball milling, sanding, spray drying, sintering and air jet pulverization to obtain multiple carbon-coated high-compaction lithium iron manganese phosphate.

Inventors

Ji Yang
Haijuan Liu
Ya HE
Yihua Wei
Jie Sun
Zhonglin He
Jianhao He
Rong Luo
Wenzhi Jiang
Nan Jiang
Guangchun Cheng

Assignees

HUBEI RT ADVANCED MATERIALS GROUP COMPANY LIMITED

Dates

Publication Date: 20260512
Application Date: 20221103
Priority Date: 20220525

Claims (6)

1 . A preparation method of multiple carbon-coated high-compaction lithium iron manganese phosphate, comprising the following steps: S1 mixing an iron source, a manganese source, a phosphorus source, a carbon source and an additive, and then synthesizing a carbon and vanadium co-doped ferromanganese phosphate precursor through a co-precipitation; and sintering the obtained carbon and vanadium co-doped ferromanganese phosphate precursor, and removing all crystal water to obtain an anhydrous ferromanganese phosphate precursor; S2 adding lithium phosphate, a supplemental phosphorus source, an organic carbon source, a dopant and deionized water into the anhydrous ferromanganese phosphate precursor obtained in step S1 and performing ball milling, wet sanding, spray drying and sintering to obtain an intermediate product; and S3 adding deionized water and the organic carbon source into the intermediate product obtained in step S2 again, performing ball milling, sanding, spray drying, sintering and air jet pulverization to finally obtain the multiple carbon-coated high-compaction lithium iron manganese phosphate material.
2 . The preparation method according to claim 1 , wherein in step S1, the iron source is ferrous sulfate, the manganese source is manganese sulfate, and the phosphorus source is one or more of phosphoric acid, ammonium dihydrogen phosphate and diammonium hydrogen phosphate, the additive is ammonium metavanadate, and the carbon source is citric acid; the iron source, the manganese source, the phosphorus source, the carbon source and the additive are weighed based on a stoichiometric proportion of each element in (Mn x Fe y V z ) 2 (PO 4 ) 3 ·mH 2 O and then mixed, wherein 0.4<x<0.8, 0.2≤y≤0.6, and 0.0005<z<0.005; the sintering is performed for 1-5 h in a box furnace at the sintering temperature of 380-680° C. at the sintering atmosphere of air.
3 . The preparation method according to claim 1 , wherein in step S2, the intermediate product satisfies a molar ratio of the intermediate product is (Fe+Mn)/P=0.958-0.998, and a molar ratio is Li/(Fe+Mn)=1.025-1.055.
4 . The preparation method according to claim 1 , wherein in step S2, the organic carbon source is a mixture of glucose and polyethylene glycol, the addition amount of glucose is 4-6 wt % of the weight of the anhydrous ferromanganese phosphate precursor, and the addition amount of polyethylene glycol is 1-2 wt % of the weight of anhydrous manganese phosphate precursor; the dopant is one or more of titanium dioxide, ammonium metavanadate, niobium pentoxide and magnesium dioxide, and the addition amount of the dopant is 0-1.5 wt % of the weight of the anhydrous ferromanganese phosphate precursor; the supplemental phosphorous source is one or more of phosphoric acid, ammonium dihydrogen phosphate and diammonium hydrogen phosphate, and the addition amount of the supplemental phosphorous source is determined based on the molar ratio Fe/P=0.958-0.966 in the multiple carbon-coated high-compaction lithium iron manganese phosphate.
5 . The preparation method according to claim 1 , wherein in step S2, the ball milling time is 0.5-2 h; in the wet sanding, the sanding granularity is controlled to D50=0.20-0.60 μm, and the solid content is controlled to 30-50 wt %; an inlet air temperature for spray drying is controlled to 180-240° C., an outlet air temperature for spray drying is controlled to 80-120° C.; the sintering is performed for 2-5 h in a box furnace at the sintering temperature of 400-550° C. at the sintering atmosphere of nitrogen.
6 . The preparation method according to claim 1 , wherein in step S3, the organic carbon source is one or more of glucose, saccharose, polyethylene glycol and polyvinyl alcohol, and the addition amount of the organic carbon source is determined based on 1.0-1.8 wt % of carbon content in the multiple carbon-coated high-compaction lithium iron manganese phosphate; the ball milling time is 0.5-2 h, in the wet sanding, the sanding granularity is controlled to D50=0.30-0.50 μm, and the solid content is controlled to 40-60 wt %; an inlet air temperature for spray drying is controlled to 180-240° C., an outlet air temperature for spray drying is controlled to 80-120° C.; the sintering is carried out for 6-15 h in a box furnace at the sintering temperature of 650-850° C. at the sintering atmosphere of nitrogen at the sintering pressure of 50-200 Pa; in the air jet pulverization, the particle size of the multiple carbon-coated high-compaction lithium iron manganese phosphate obtained by pulverization is D10≥0.30 μm, D50=1-2 μm and D90≤20 μm.

Description

TECHNICAL FIELD The present disclosure belongs to the technical field of lithium battery cathode materials, and particularly relates to a preparation method of multiple carbon-coated high-compaction lithium iron manganese phosphate. BACKGROUND At present, a novel lithium battery cathode material is developed around high-voltage platforms and manganese-based materials, and the earliest commercialized lithium battery cathode material in its branch system is lithium manganese iron phosphate which has high voltage, high energy density and excellent low temperature property relative to lithium iron phosphate; and has low cost, high safety and long cycle life relative to a ternary material. Lithium manganese iron phosphate itself has performance deficiency. At the stage of wet grinding, a variety of phases are mixed in a proportion, but the uniform mixing effect is difficult to achieve since there are differences in the aspects of particle morphology and looseness, so as to result in poor uniformity of the finally produced lithium manganese iron phosphate finished product phase; due to no consecutive coplanar octahedral network in its structure, movement of lithium ions in a one-dimensional channel is limited, leading to poor material conductivity. SUMMARY In order to solve the drawbacks in the prior art, the objective of the present disclosure is to provide a preparation method of a multiple carbon-coated high-compaction lithium iron manganese phosphate material. The multiple carbon-coated high-compaction lithium iron manganese phosphate material is uniform in phase, better and denser in carbon coating effect, more uniform in doping and better in conductivity. In order to realize the above objective, the present disclosure adopts the following technical solution: Provided is a preparation method of multiple carbon-coated high-compaction lithium iron manganese phosphate, comprising the following steps: (1) mixing an iron source, a manganese source, a phosphorus source, a carbon source and an additive, and then synthesizing a carbon and vanadium co-doped ferromanganese phosphate precursor through a co-precipitation; and sintering the obtained ferromanganese phosphate precursor, and removing all crystal water to obtain an anhydrous ferromanganese phosphate precursor;(2) adding lithium phosphate, a supplemental phosphorus source, an organic carbon source, a dopant and deionized water into the anhydrous ferromanganese phosphate precursor obtained in step (1), and performing ball milling, wet sanding, spray drying and sintering to obtain an intermediate product; and(3) adding deionized water and the organic carbon source into the intermediate product obtained in step (2) again, performing ball milling, sanding, spray drying, sintering and air jet pulverization to finally obtain the multiple carbon-coated high-compaction lithium iron manganese phosphate material. Preferably, in step (1), the iron source is ferrous sulfate, the manganese source is manganese sulfate, and the phosphorus source is one or more of phosphoric acid, ammonium dihydrogen phosphate and diammonium hydrogen phosphate, the additive is ammonium metavanadate, and the carbon source is citric acid; the iron source, the manganese source, the phosphorus source, carbon source and the additive are weighed based on a stoichiometric proportion of each element in (MnxFeyVz)2(PO4)3·mH2O, wherein 0.4<x<0.8, 0.2≤y≤0.6, and 0.0005<z<0.005; the sintering is performed for 1-5 h in a box furnace at the sintering temperature of 380-680° C. at the sintering atmosphere of air. Preferably, in step (2), a molar ratio of the intermediates is (Fc+Mn)/P=0.958-0.998, and a molar ratio is Li/(Fe+Mn)=1.025-1.055. Preferably; in step (2), the organic carbon source is a mixture of glucose and polyethylene glycol, the addition amount of glucose is 4-6 wt % of the weight of the anhydrous ferromanganese phosphate precursor, and the addition amount of polyethylene glycol is 1-2 wt % of the weight of anhydrous manganese phosphate precursor; the dopant is one or more of titanium dioxide, ammonium metavanadate, niobium pentoxide and magnesium dioxide, and the addition amount of the dopant is 0-1.5 wt % of the weight of the anhydrous ferromanganese phosphate precursor; the supplemental phosphorous source is one or more of phosphoric acid, ammonium dihydrogen phosphate and diammonium hydrogen phosphate, and the addition amount of the supplemental phosphorous source is determined based on a molar ratio Fe/P=0.958-0.966 in multiple carbon-coated high-compaction lithium iron manganese phosphate. Preferably, in step (2), the ball milling time is 0.5-2 h; in the wet sanding, the sanding granularity is controlled to D50=0.20-0.60 μm, and the solid content is controlled to 30-50 wt %; an inlet air temperature for spray drying is controlled to 180-240° C., an outlet air temperature for spray drying is controlled to 80-120° C.; the sintering is performed for 2-5 h in a box furnace at the sintering