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High-volume and capacity ratio spherical lithium ferric phosphate and preparation method thereof

A technology of lithium iron phosphate and specific capacity, which is applied in the field of lithium-ion battery cathode materials and its preparation, can solve the problems of low tap density, low volume specific capacity, and low electronic conductivity, and achieve the effect of preventing rapid growth

Inactive Publication Date: 2010-09-01
SUN YAT SEN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But LiFePO 4 There are two obvious disadvantages: one is the low electronic conductivity, resulting in poor high-rate charge and discharge performance and low actual specific capacity; the other is low tap density, resulting in low volume specific capacity
However, the shortcoming of low tap density has not been well resolved, LiFePO 4 The theoretical density is only 3.6g / cm 3 , much lower than that of LiCoO 2 (5.1g / cm 3 ), LiNiO 2 (4.8g / cm 3 ) and LiMn 2 o 4 (4.2g / cm 3 )
However, in these published patents, the method for preparing spherical lithium iron phosphate requires high process control, the process is complicated, and it is difficult to realize industrialization

Method used

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  • High-volume and capacity ratio spherical lithium ferric phosphate and preparation method thereof
  • High-volume and capacity ratio spherical lithium ferric phosphate and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] 0.21 g of LiOH·H 2 O was added to the prepared 0.5mol / L HNO 3 Dissolve in the solution, then add 1.11 g of FePO 4 4H 2 O and 0.44 g vitamin C, stir the solution and mix well. use NH 3 The water was adjusted to just precipitate (pH = 7). Then the solution was put into a microwave oven, and the solvent was evaporated to dryness by alternately heating for 5 seconds and intermittently for 5 seconds to obtain a yellow powder. Grind the obtained yellow powder into fine particles, put it into a porcelain boat, put it into a high-temperature furnace, and raise the temperature to 700°C at a rate of 5°C / min in a high-purity nitrogen atmosphere, and keep it warm for 6 hours to obtain a spherical lithium iron phosphate sample. The tap density is 2g / cm 3 . XRD test shows pure lithium iron phosphate with olive structure. The topography of the sample and the first charge-discharge curve at 0.1C are shown in figure 1 and figure 2 middle. Such as figure 1 As shown, the obta...

Embodiment 2

[0026] Weigh out 0.52 g of CH 3 COOLi·2H 2 O was added to the prepared 0.5mol / L HNO 3 Dissolve in the solution, then add 1.11 g of FePO 4 4H 2 O and 0.44 g vitamin C, stir the solution and mix well. use NH 3 The water was adjusted to just precipitate (pH = 7). Then the solution was put into a microwave oven, and the solvent was evaporated to dryness by alternately heating for 5 seconds and intermittently for 30 seconds to obtain a yellow powder. Grind the obtained yellow powder into fine particles, put it into a porcelain boat, put it into a high-temperature furnace, and raise the temperature to 700°C at a rate of 5°C / min in a high-purity nitrogen atmosphere, and keep it warm for 6 hours to obtain a spherical lithium iron phosphate sample. The tap density is 1.7g / cm 3 .

Embodiment 3

[0028] 0.19 g of Li 2 CO 3 Add prepared 0.5mol / L HNO 3 Dissolve in the solution, then add 1.11 g of FePO 4 4H2 O and 0.44 g vitamin C, stir the solution and mix well. use NH 3 The water was adjusted to just precipitate (pH = 7). Then the solution was put into a microwave oven, and the solvent was evaporated to dryness by alternately heating for 10 seconds and intermittently for 30 seconds to obtain a yellow powder. Grind the obtained yellow powder into fine particles, put it into a porcelain boat, put it into a high-temperature furnace, and raise the temperature to 700°C at a rate of 5°C / min in a high-purity nitrogen atmosphere, and keep it warm for 6 hours to obtain a spherical lithium iron phosphate sample. The tap density is 1.7g / cm 3 .

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Abstract

The invention discloses high-volume and capacity ratio spherical lithium ferric phosphate and a preparation method thereof. The method comprises the following steps of: preparing a spherical precursor by combining with an alternative microwave / solvent hot method, then heating at high temperature under the protection of inert gas to obtain regularly spherical lithium ferric phosphate, wherein the tap density of the prepared lithium ferric phosphate reaches 2g / cm3. The method of the invention can be used for controlling the degree of crystallization and the granule size of the heated material. Meanwhile, the method also can control the structure and the composition of a phase through regulating the proportions of raw materials, thereby ensuring that the combined product has the quality meeting requirements.

Description

technical field [0001] The invention relates to a lithium ion battery cathode material and a preparation method thereof, in particular to a preparation method of spherical lithium iron phosphate with high volume density. Background technique [0002] Lithium-ion battery, as an environmentally friendly high-performance rechargeable battery, has been used more and more in various electronic products and communication tools. Electric vehicles powered by high-energy secondary batteries and hybrid electric vehicles powered by fuel and batteries have received more and more attention. Research on various new electrode materials. Among the new cathode materials for lithium-ion batteries, orthorhombic olivine-type LiFePO 4 It has the characteristics of high capacity and stable charging and discharging voltage. In particular, its low price, good safety, good thermal stability, and no pollution to the environment make it one of the most potential positive electrode materials. But L...

Claims

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Application Information

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IPC IPC(8): C01B25/45
Inventor 沈培康邹红丽
Owner SUN YAT SEN UNIV
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