Porous manganese phosphate lithium-carbon composite material and preparation method

A technology of lithium iron manganese phosphate and carbon composite material, applied in nanotechnology, structural parts, electrical components and other directions for materials and surface science, can solve the problems of high cost, complex preparation method, low volume energy density, etc. The effect of low carbon content, simple preparation method and high active substance content

Active Publication Date: 2013-06-05
中科致良新能源材料(浙江)有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Although it has been reported that nano-scale lithium manganese phosphate materials have been obtained by hydrothermal method, sol-gel method and other methods, the preparation method is complicated, the cost is high, and the tap density of dispersed nanoparticles is very low, resulting in very low volumetric energy density. low, not conducive to practical application
In addition, since LiMnPO 4 It does not have a good affinity with carbon, and the effect of carbon coating in the existing preparation methods is generally unsatisfactory. In order to obtain a higher discharge capacity, it is necessary to add a proportion of up to 20-30wt% carbon, which further reduces the power density of the battery

Method used

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  • Porous manganese phosphate lithium-carbon composite material and preparation method

Examples

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Embodiment 1

[0028] Example 1: Take 18mL 50%Mn(NO 3 ) 2 Aqueous solution, 20mL 85%H 3 PO 4 Aqueous solution, 70mL ethanol, 20mL water were mixed and stirred at 25°C for 18 hours to prepare MnPO 4 ·H 2 O material, after filtration and drying, was heat-treated in an Ar atmosphere at 600 °C for 10 h to obtain the intermediate product Mn 2 P 2 o 7 , the scanning electron micrograph (SEM) of the sample as figure 1 As shown, it can be seen that the primary particle size is about 50nm, and they are agglomerated together to form microspheres, and there are nanoholes of 5-50nm between the particles. Weigh 0.8g Mn 2 P 2 o 7 With 0.44g ferrous oxalate (FeC 2 o 4 ), 0.39g lithium hydroxide (LiOH·H 2 O), 0.28g ammonium dihydrogen phosphate (NH 4 h 2 PO 4 ), 0.2 g of polyethylene glycol (PEG), mixed with 15 mL of ethanol for ball milling for 6 h, and then dried at 80° C. to obtain the second reaction precursor. The second reaction precursor was heat-treated at 600°C for 10 hours in an...

Embodiment 2

[0030] Example 2: Take 18mL 50%Mn(NO 3 ) 2 Aqueous solution, 20mL 85%H 3 PO 4 Aqueous solution, 70mL ethanol, 20mL water were mixed and stirred at 25°C for 18 hours to prepare MnPO 4 ·H 2 O material, after filtration and drying, heat treatment in air atmosphere at 600 °C for 5 h to obtain the intermediate product Mn 2 P 2 o 7 . Weigh 0.8g Mn 2 P2 o 7 With 0.44g ferrous oxalate (FeC 2 o 4 ), 0.39g lithium hydroxide (LiOH·H 2 O), 0.28g ammonium dihydrogen phosphate (NH 4 h 2 PO 4 ), 0.4 g of PEG, mixed with 15 mL of ethanol for ball milling for 6 h, and then dried at 80° C. to obtain the second reaction precursor. The second reaction precursor was heat-treated at 600°C for 10 hours in an Ar flow to obtain the final product, in which the general structural formula of the lithium manganese iron phosphate material was LiMn 0.7 Fe 0.3 PO 4 . The carbon content in the composite material is about 4wt% as determined by an elemental analyzer. By using the same meth...

Embodiment 3

[0031] Example 3: Take 18mL 50%Mn(NO 3 ) 2 Aqueous solution, 20mL 85%H 3 PO 4 Aqueous solution, 70mL ethanol, 20mL water were mixed and stirred at 25°C for 18 hours to prepare MnPO 4 ·H 2 O material, after filtration and drying, was heat-treated at 600 °C for 5 h in an Ar atmosphere to obtain the intermediate product Mn 2 P 2 o 7 . Weigh 1.42g Mn 2 P 2 o 7 With 0.4g lithium carbonate (Li 2 CO 3 ), 0.5 g of glucose, and added 15 mL of ethanol for ball milling for 6 h, then dried at 80° C. to obtain the second reaction precursor. The second reaction precursor was heat-treated at 700°C for 10 hours in an Ar flow to obtain the final product, whose general structure is LiMnPO 4 . The carbon content in the composite material is about 8wt% as determined by an elemental analyzer. By using the same method as in Example 1, the first discharge specific capacity of the positive electrode material was measured to be 30mAh / g.

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Abstract

The invention discloses a porous manganese phosphate lithium-carbon composite material and a preparation method. The composite material comprises a manganese phosphate lithium material and 1%-15wt% of carbon element, a composition general formula of the manganese phosphate lithium material is LiMnxFe1-xPO4, wherein 0.6<=x<=1, and the particle size of the composite material is 1-50 mum, a plurality of holes with 3-50nm of aperture is provided in the composite material, the material thickness between the adjacent holes is 20-70nm, and the preparation method comprises the following steps: mixing porous Mn2P2O7 with ferric salt, a lithium source, phosphate and a carbon source, performing ball milling by a wet method, drying to prepare a reaction precursor, under protective atmosphere, and performing constant temperature calcination on the reaction precursor for 1-30h at the temperature of 500-900 DEG C to obtain the target product. The porous manganese phosphate lithium-carbon composite material has the advantages that 1) the composite material is the micron order manganese phosphate lithium material having nano holes, when the composite material is taken as lithium ion batteries cathode materials for using, the composite material has high specific capacity, rate capability and tap density; and 2) the composite material has the advantages of simple preparation method, low carbon content and high active substance content.

Description

technical field [0001] The invention particularly relates to a lithium manganese iron phosphate-carbon composite material with a porous nanostructure and a preparation method thereof, belonging to the field of new energy materials. Background technique [0002] Phosphate-like material LiMPO with olivine structure 4 (M=Fe, Mn, Ni, Co) is used as the positive electrode material of lithium-ion batteries, and its theoretical capacity is about 170mAh / g. It also has stable structure, low reactivity with electrolyte, high safety, and good battery cycle performance, etc. Many advantages. Among such phosphate materials, LiFePO 4 The synthesis of materials is relatively simple, and large-scale production and sales have been realized. However, LiFePO 4 Due to the low potential platform (about 3.4V) of lithium intercalation, the material reduces the overall energy density of the battery and limits its development in electric vehicles. while LiMnPO 4 The working voltage for Li is 4...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/58H01M4/62B82Y30/00
CPCY02E60/12Y02E60/10
Inventor 刘涛吴晓东
Owner 中科致良新能源材料(浙江)有限公司
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