Titanium sub-oxide coated and modified lithium iron phosphate composite material and preparation method thereof

A technology of lithium iron phosphate and titanium oxide, which is applied in the field of lithium ion materials, can solve the problems that lithium iron phosphate cannot meet the needs of power batteries, low lithium ion diffusion rate, poor corrosion resistance, etc., and achieve high-rate charge and discharge improvement ability, stable chemical properties, and the effect of reducing the internal resistance of the battery

Active Publication Date: 2016-04-13
李震祺 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] The anode material of the commercialized lithium iron battery is lithium iron phosphate, which has a theoretical capacity of up to 170mAh/g, good cycle performance and safety performance, making it the main force of power lithium-ion batteries, but because lithium iron phosphate has a low Li-ion diffusion rate (10 -14 ~10 -10 cm 2 /s) and low electronic conductivity (-9 s/cm), making lithium iron phosphate unable to meet the needs of power batteries
Conventionally, carbon coating is of

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0027] Example 1

[0028] A titanium suboxide coated modified lithium iron phosphate composite material whose molecular formula is LiFePO 4 / Ti 4 O 7 , The coating amount of titanium suboxide is 5%. Prepare using the following steps:

[0029] Step S1: First, weigh 143.86g of ferrous oxalate and 103.93g of lithium dihydrogen phosphate according to the molar ratio of Fe:Li:P to 1:1:1. The ferrous oxalate, Lithium dihydrogen phosphate was ball milled and mixed in ethanol medium for 4 hours, dried at 80°C, cooled naturally, and ball milled for 2 hours to mix uniformly, and then heated in an Ar atmosphere furnace at 600°C for 12 hours, and lithium iron phosphate powder was obtained after natural cooling.

[0030] Step S2: At room temperature, disperse tetrabutyl titanate and water in anhydrous ethanol at a volume ratio of 1:5, add dropwise acetic acid equivalent to 1 / 5 volume of tetrabutyl titanate during stirring, and continue stirring for 20 minutes to obtain For a uniform and transpa...

Example Embodiment

[0033] Example 2

[0034] A titanium suboxide coated modified lithium iron phosphate composite material is prepared by adopting the following steps:

[0035] Step S1: First, weigh 246 g of ferrous citrate, 37.68 g of lithium carbonate, and diammonium hydrogen phosphate according to the molar ratio of Fe:Li:P of 1:1.02:1. 132.06g, put the above three raw materials in ethanol medium, ball mill and mix for 4 hours, dry at 80°C, cool naturally, continue to ball mill for 2 hours to mix uniformly, and then heat at 650°C for 10 hours in an Ar gas atmosphere furnace, and obtain phosphoric acid after natural cooling Lithium iron powder.

[0036] Step S2: At room temperature, disperse tetrabutyl titanate and water in anhydrous ethanol at a volume ratio of 1:5, add dropwise acetic acid equivalent to 1 / 5 volume of tetrabutyl titanate during stirring, and continue stirring for 20 minutes to obtain For a uniform and transparent light yellow solution, dropwise add deionized water equivalent to 1 / ...

Example Embodiment

[0039] Example 3

[0040] A titanium suboxide coated modified lithium iron phosphate composite material is prepared by adopting the following steps:

[0041] Step S1: First, weigh 143.86 g of ferrous oxalate, 38.79 g of lithium carbonate and 115.03 of ammonium dihydrogen phosphate according to the Fe:Li:P molar ratio of 1.00:1.03:1.00. g. Mix the above three raw materials in ethanol medium by ball milling for 4 hours, drying at 80°C, natural cooling, continuing to ball mill for 2 hours to mix uniformly, and then heating at 700°C for 8 hours in an Ar gas atmosphere furnace, and obtaining lithium iron phosphate after natural cooling powder.

[0042] Step S2: At room temperature, disperse tetrabutyl titanate and water in anhydrous ethanol at a volume ratio of 1:5, add dropwise acetic acid equivalent to 1 / 5 volume of tetrabutyl titanate during stirring, and continue stirring for 20 minutes to obtain To uniform and transparent light yellow solution, dropwise add deionized water equivale...

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Abstract

The invention provides a titanium sub-oxide coated and modified lithium iron phosphate composite material and a preparation method thereof. The surface of lithium iron phosphate is coated with titanium sub-oxide, the molecular formula of the titanium sub-oxide coated and modified lithium iron phosphate composite material is LiFePO4/Ti4O7, and the covering amount of titanium sub-oxide is 5%-10%. With the adoption of the technical scheme provided by the invention, the lithium iron phosphate material is coated with and modified by titanium sub-oxide with high conductivity, so that the high-rate charge/discharge capacity of lithium iron phosphate is obviously improved, the cycling capacity degradation of lithium iron phosphate at high current density is reduced, and the high-rate cycle performance of lithium iron phosphate is further improved; at the same time, the internal resistance of a battery is effectively reduced, the specific power of a lithium iron phosphate power battery is increased, the adaptation to the deep cycle requirement of the power battery is facilitated, the preparation process is simple and convenient, and the composite material is also suitable for large-scale industrial production.

Description

technical field [0001] The invention belongs to the technical field of lithium ion materials, and in particular relates to a titanium oxide-coated modified lithium iron phosphate composite material and a preparation method thereof. Background technique [0002] The anode material of the commercialized lithium iron battery is lithium iron phosphate, which has a theoretical capacity of up to 170mAh / g, good cycle performance and safety performance, making it the main force of power lithium-ion batteries, but because lithium iron phosphate has a low Li-ion diffusion rate (10 -14 ~10 -10 cm 2 / s) and low electronic conductivity (<10 -9 s / cm), making lithium iron phosphate unable to meet the needs of power batteries. Conventionally, carbon coating is often used to improve the conductivity of lithium iron phosphate, but the specific surface area of ​​carbon is too large, the dispersion is not good, and the corrosion resistance is poor, which leads to the attenuation of batte...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/58H01M4/62H01M10/0525
CPCH01M4/366H01M4/5825H01M4/624H01M10/0525Y02E60/10
Inventor 李震祺刘立君宋翠环
Owner 李震祺
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