Graphene/phosphoric acid iron-lithium composite material with sandwich structure and preparation method thereof

A lithium iron phosphate and composite material technology, applied in the field of nanomaterials, can solve the problems of limited material application, poor rate charge and discharge performance, etc., and achieve the effects of improving material purity, low process temperature, and short preparation cycle

Inactive Publication Date: 2011-08-10
SHANGHAI UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, LiFePO4 material has low electronic conductivity (10-9~10-10 S / cm) and lithium ion diffusion coefficient (1.8x10 -14 cm2 / S), resulting in extremely poor rate charge and discharge performance, which limits the application of this material

Method used

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  • Graphene/phosphoric acid iron-lithium composite material with sandwich structure and preparation method thereof
  • Graphene/phosphoric acid iron-lithium composite material with sandwich structure and preparation method thereof
  • Graphene/phosphoric acid iron-lithium composite material with sandwich structure and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035] Weigh 2.5g of potassium persulfate and 2.5g of phosphorus pentoxide, dissolve them in 12mL of concentrated sulfuric acid, and heat to 80°C; add 3g of natural graphite powder to the above solution, keep it at 80°C for 4 hours; cool to room temperature, and deionize with 500mL After diluting with water, let it stand overnight; filter and dry in a vacuum oven at 60°C; dissolve the above product in 120mL of concentrated sulfuric acid, slowly add 15g of potassium permanganate into the solution, stir at 35°C for 2 hours, then slowly dilute with 250mL of water , let stand for 2 hours; put 20mLH 2 o 2 (30wt%) was added to the above solution; filtered and then washed with 1 L of HCl solution with a volume ratio of 1:10, and ultrasonicated for 15 minutes; 5ml of isopropanol was added, and then ultrasonicated for 15 minutes to obtain a graphene solution.

[0036] Take 67mL of the above solution, add deionized water to dilute to 500mL, add 1.40 g FeSO 4 ·7H 2 O, stirred at room...

Embodiment 2

[0041] Take 56 mL of graphene solution with a concentration of 3 mg / mL, add deionized water to dilute to 500 mL, add 1.0 g FeCl 2 4H 2 O, stirred at room temperature for 10 min, then added 0.61 g of diammonium hydrogen phosphate, stirred for 10 min; added dropwise 0.33 g of H 2 o 2 (30wt%), stirred at room temperature for 3 hours, centrifuged and washed three times with deionized water, the resulting paste was placed in a blast oven, dried at 80°C for 5 hours, ground into powder, placed in a tube furnace, and Under the condition of nitrogen protection, annealing at 400°C for 4 hours and then cooling naturally, a graphene / iron phosphate composite material with crystal water removed was obtained.

[0042] Dissolve 4.02 g LiI in 60 mL of acetonitrile, then add 1.50 g of annealed graphene / iron phosphate composite material; stir at room temperature for 12 hours, centrifuge and wash with acetonitrile for 3 times, and place the obtained precipitate in a vacuum drying oven and dry ...

Embodiment 3

[0044] Take 74 mL of graphene solution with a concentration of 3 mg / mL, add deionized water to dilute to 500 mL, add 1.98 g Fe(NH 4 ) 2 (SO 4 ) 2 ·6H 2 O, stirred at room temperature for 10 min, then added 0.41 g of phosphoric acid, stirred for 10 min; added dropwise 0.27 g of H 2 o 2 (30wt%), stirred at room temperature for 4 hours, centrifuged and washed three times with deionized water, the resulting paste was placed in a blast oven, dried at 80°C for 4 hours, ground into powder, placed in a tube furnace, and Under the condition of nitrogen protection, annealing at 400°C for 5 hours and then cooling naturally, a graphene / iron phosphate composite material with crystal water removed was obtained.

[0045] Take 1.13 g of annealed graphene / iron phosphate composite material, add lithium carbonate raw material at a molar ratio of Fe ion and Li ion 1:1, fully grind and mix for 1 hour, then place the mixture in a tube furnace, (Ar / H 2 The volume ratio is 95:5), calcined at ...

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Abstract

The invention relates to a graphene / phosphoric acid iron-lithium composite material with a 'sandwich' structure and a preparation method thereof. The structure characteristics of the graphene / phosphoric acid iron-lithium composite material are that: blocky particles are formed by a grapheme laminated sheet which is completely coated by a phosphoric acid iron-lithium shell; and the insides of the particles present a similar 'sandwich' structure overlapped by a plurality of layers of phosphoric acid iron-lithium and graphene one by one. The preparation method thereof adopts a 'two-step' method. The characteristic steps are as follows: a graphene / phosphoric acid iron precursor with a 'sandwich' structure is compounded by a liquid phase method during the first step; then lithium is embedded in the second step; lithium iodide liquid phase low temperature reaction is adopted for embedding the lithium; then the graphene / phosphoric acid iron-lithium composite material is obtained through high temperature calcination under reducing (inertia) atmospheres; moreover, the graphene / phosphoric acid iron-lithium composite material can also be formed by the embedding of the lithium through high temperature solid phase reaction. The graphene / phosphoric acid iron-lithium composite material prepared by the method has high capacity and good charging-discharging circulating performances, and is suitable to be used as an anode material of a lithium ion battery.

Description

technical field [0001] The invention relates to a sandwich-structured graphene / lithium iron phosphate composite material and a preparation method thereof, which is suitable for preparing positive electrode materials of lithium ion batteries and belongs to the technical field of nanometer materials. Background technique [0002] Due to the advantages of high voltage, high energy density, good cycle performance, small self-discharge, and no memory effect, lithium-ion batteries have already occupied the market in the field of mobile electronic terminal equipment such as notebook computers, mobile phones, and camcorders due to their excellent cost-effective advantages. took a dominant position. At the same time, the application of lithium-ion batteries in electric vehicles, uninterruptible power supplies, and large-scale communication power supplies also has broad prospects. [0003] The improvement of the performance of lithium-ion batteries mainly depends on the improvement o...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/13H01M4/139
CPCY02E60/12Y02E60/122Y02E60/10
Inventor 赵兵仲明阳宋劲松刘鹏徐为文方涛焦正吴明红
Owner SHANGHAI UNIV
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