CN101656308A - Sol-gel method for preparing positive electrode material Li3V2(PO4)3 of lithium ion battery - Google Patents

Abstract

The invention discloses a sol-gel method for preparing a positive electrode material Li3V2(PO4)3 of a lithium ion battery. The method comprises the following steps: heating vanadic anhydride powder to800 DEG C; keeping temperature for 2 hours to melt the powder; rapidly pouring the molten powder into a container with water to form a brownish red solution; adding a chelating agent with reducibility, lithium salt and phosphate into the brownish red solution, uniformly stirring and mixing; drying the mixture in an oven at 100 DEG C for 4 hours to obtain a precursor; sintering the obtained precursor at 400-550 DEG C for 5-8 hours under the protection of inert gases; and cooling to obtain a finished product Li3V2(PO4)3. The invention simplifies the synthesis process, decreases the synthesis cost, lowers the synthesis temperature, shortens the synthesis time and improves the charging and discharging performance and the circulating performance of a sample.

Description

Sol-gel process prepares anode material for lithium-ion batteries Li 3V 2(PO 4) 3

Technical field

The present invention relates to a kind of sol-gel process and prepare anode material for lithium-ion batteries Li ₃V ₂(PO ₄) ₃

Background technology

Li ₃V ₂(PO ₄) ₃It is good that material has a reversibility, the advantages such as abundant raw materials, specific capacity height (theoretical capacity is 197mAh/g).But it has following shortcoming and has hindered its practical application: V during (1) is synthetic ³⁺Easily be oxidized to V ⁵⁺, be difficult to obtain single-phase Li ₃V ₂(PO ₄) ₃(2) lithium ion is at Li ₃V ₂(PO ₄) ₃Middle diffusion difficulty causes the utilization rate of active material low; (3) Li ₃V ₂(PO ₄) ₃The electrical conductivity of itself is also very low, causes its heavy-current discharge performance poor.Existing research improves Li by following several respects ₃V ₂(PO ₄) ₃Performance: (1) adopts inert atmosphere to protect V ³⁺(2) Li of synthetic small particle diameter ₃V ₂(PO ₄) ₃Improve the insertion of lithium ability; (3) add conductive agent and improve electrical conductivity.

At present to lithium ion secondary battery anode material Li ₃V ₂(PO ₄) ₃Study fewerly, J.Barker etc adopts solid phase synthesis process that it has been carried out studying (the patent No.: 5,871,866).Solid phase reaction is because the synthesis temperature height, thereby causes the particle of sample bigger, thus chemical property especially cycle performance is relatively poor.Zhao Yanming (200610123670.8) adopts sol-gal process that it is studied, but must at first synthesize pentoxide gel, and the reaction time is long, operates more loaded down with trivial details.

Summary of the invention

The object of the present invention is to provide a kind of sol-gel process to prepare anode material for lithium-ion batteries Li ₃V ₂(PO ₄) ₃, to overcome the shortcoming and defect of prior art.

Concrete steps are:

(1) the 0.09-0.11mol vanadium pentoxide powder is heated to 800 ℃, and constant temperature 2h makes to pour into rapidly in the container that water is housed after its fusion and forms brown-red solution;

(2) add chelating agent, lithium salts and the phosphate with reproducibility in step (1) gained brown-red solution, after mixing, drying promptly got presoma in 4 hours in 100 ℃ of baking ovens;

(3) with the presoma that obtains under the protection of inert gas in 400 ℃ of-550 ℃ of sintering 5-8h, be finished product Li after the cooling ₃V ₂(PO ₄) ₃

Described chelating agent with reproducibility is a kind of in ascorbic acid, adipic acid, malonic acid and the citric acid, and the consumption of ascorbic acid, adipic acid, malonic acid and citric acid is 0.09-0.11mol;

Described lithium salts is a kind of in lithium acetate and the lithium nitrate, and the consumption of lithium acetate and lithium nitrate is 0.28-0.32mol;

Described phosphate is a kind of in ammonium dihydrogen phosphate, diammonium hydrogen phosphate and the triammonium phosphate, and the consumption of ammonium dihydrogen phosphate, diammonium hydrogen phosphate and triammonium phosphate is 0.28-0.32mol;

Described inert gas is a kind of in nitrogen and the argon gas.

The inventive method is simple, generated time is short, synthesis temperature is low, thereby has suppressed growing up of sample particle, the particle diameter of institute's synthetic material is evenly distributed, tiny, has reduced synthetic cost; And the Li that obtains ₃V ₂(PO ₄) ₃Material electrochemical performance is good, has good charge/discharge capacity and cyclical stability.This method can take full advantage of the vanadium resource of China's abundant, has solved the deficiency of cobalt resource, and has reduced the pollution of pentavalent vanadium to environment, and this method itself can be to environment yet.

Description of drawings

Fig. 1 is No. 3 sample Li of the embodiment of the invention 1 ₃V ₂(PO ₄) ₃XRD figure.

Fig. 2 is No. 3 sample Li of the embodiment of the invention 1 ₃V ₂(PO ₄) ₃SEM figure.

Fig. 3 is No. 3 sample Li of the embodiment of the invention 1 ₃V ₂(PO ₄) ₃The first charge-discharge curve.

Fig. 4 is No. 3 sample Li of the embodiment of the invention 1 ₃V ₂(PO ₄) ₃The cycle performance curve.

Embodiment

Embodiment 1:

The 0.095mol vanadium pentoxide powder is heated to 800 ℃, and constant temperature 4h makes to pour into rapidly in the container that water is housed after its melting and forms brown-red solution, in brown-red solution, add 0.31mol lithium acetate, 0.305mol diammonium hydrogen phosphate and 0.105mol ascorbic acid then, after mixing, drying namely got presoma in 4 hours in 100 ℃ of baking ovens; With the presoma that obtains under the protection of nitrogen respectively at 400 ℃, 450 ℃, 500 ℃, 550 ℃ sintering 5h, be finished product Li after the cooling ₃V ₂(PO ₄) ₃Resulting product shows to be Li through X-ray diffraction analysis ₃V ₂(PO ₄) ₃, do not have any dephasign, can obtain the particle diameter of product by SEM about 0.5 μ m.With resulting product be assembled into the experiment button cell survey its charging and discharging capacity and cycle performance, under the multiplying power of 1C, discharge and recharge, its first discharge capacity and the circulation 30 times after discharge capacity see Table 1.

The experiment condition of table 1 embodiment 1 and result

Numbering	Sintering temperature/℃	Sintering time/h	Initial charge capacity/mAhg -1	Discharge capacity/mAhg first -1	The 30th discharge capacity/mAhg -1
						1	400	5	126	117	108
2	450	5	130	122	113
						3	500	5	135	129	124
4	550	5	129	119	109

Embodiment 2:

The 0.095mol vanadium pentoxide powder is heated to 800 ℃, and constant temperature 2h makes to pour into rapidly in the container that water is housed after its melting and forms brown-red solution, in brown-red solution, add 0.30mol lithium nitrate, 0.30mol ammonium dihydrogen phosphate (ADP) and 0.10mol adipic acid then, after mixing, drying namely got presoma in 4 hours in 100 ℃ of baking ovens; With the presoma that obtains under the protection of argon gas in 500 ℃ of sintering 5,6,7 and 8h respectively, be finished product Li after the cooling ₃V ₂(PO ₄) ₃Resulting product shows to be Li through X-ray diffraction analysis ₃V ₂(PO ₄) ₃, do not have any dephasign, can obtain the particle diameter of product by SEM about 0.5 μ m.With resulting product be assembled into the experiment button cell survey its charging and discharging capacity and cycle performance, under the multiplying power of 1C, discharge and recharge, its first discharge capacity and the circulation 30 times after discharge capacity see Table 2.

The experiment condition of table 2 embodiment 2 and result

Numbering	Sintering temperature/℃	Sintering time/h	Initial charge capacity/mAhg -1	Discharge capacity/mAhg first -1	The 30th discharge capacity/mAhg -1
						1	500	5	115	90	72
2	500	6	120	111	91
						3	500	7	133	126	120
4	500	8	129	117	105

Embodiment 3:

The 0.105mol vanadium pentoxide powder is heated to 800 ℃, and constant temperature 2h makes to pour into rapidly in the container that water is housed after its melting and forms brown-red solution, in brown-red solution, add 0.305mol lithium acetate, 0.31mol triammonium phosphate and 0.105mol malonic acid then, after mixing, drying namely got presoma in 4 hours in 100 ℃ of baking ovens; With the presoma that obtains under the protection of argon gas in respectively at 420 ℃, 470 ℃, 520 ℃, 540 ℃ sintering 8h, be finished product Li after the cooling ₃V ₂(PO ₄) ₃Resulting product shows to be Li through X-ray diffraction analysis ₃V ₂(PO ₄) ₃, do not have any dephasign, can obtain the particle diameter of product by SEM about 0.5 μ m.With resulting product be assembled into the experiment button cell survey its charging and discharging capacity and cycle performance, under the multiplying power of 1C, discharge and recharge, its first discharge capacity and the circulation 30 times after discharge capacity see Table 3.

The experiment condition of table 3 embodiment 3 and result

Numbering	Sintering temperature/℃	Sintering time/h	Initial charge capacity/mAhg -1	Discharge capacity/mAhg first -1	The 30th discharge capacity/mAhg -1
						1	420	8	108	93	73
2	470	8	128	110	99
						3	520	8	132	123	115
4	540	8	116	99	74

Embodiment 4:

The 0.10mol vanadium pentoxide powder is heated to 800 ℃, and constant temperature 2h makes to pour into rapidly in the container that water is housed after its melting and forms brown-red solution, in solution, add 0.29mol lithium nitrate, 0.29mol ammonium dihydrogen phosphate (ADP) and 0.095mol citric acid then, after mixing, drying namely got presoma in 4 hours in 100 ℃ of baking ovens; With the presoma that obtains under the protection of nitrogen in 470 ℃ of respectively sintering 5.5,6.5,7.5,7.9h, be finished product Li after the cooling ₃V ₂(PO ₄) ₃Resulting product shows to be Li through X-ray diffraction analysis ₃V ₂(PO ₄) ₃, do not have any dephasign, can obtain the particle diameter of product by SEM about 0.5 μ m.With resulting product be assembled into the experiment button cell survey its charging and discharging capacity and cycle performance, under the multiplying power of 1C, discharge and recharge, its first discharge capacity and the circulation 30 times after discharge capacity see Table 4.

The experiment condition of table 4 embodiment 4 and result

Numbering	Sintering temperature/℃	Sintering time/h	Initial charge capacity/mAhg -1	Discharge capacity/mAhg first -1	The 30th specific discharge capacity/mAhg -1
						1	470	5.5	125	110	95
2	470	6.5	120	106	97
						3	470	7.5	130	121	109
4	470	7.9	119	104	88

Claims (1)

1. anode material for lithium-ion batteries Li ₃V ₂(PO ₄) ₃The preparation method, it is characterized in that concrete steps are:

(1) the 0.09-0.11mol vanadium pentoxide powder is heated to 800 ℃, and constant temperature 2h makes to pour into rapidly in the container that water is housed after its fusion and forms brown-red solution;

(2) add chelating agent, lithium salts and the phosphate with reproducibility in step (1) gained brown-red solution, after mixing, drying promptly got presoma in 4 hours in 100 ℃ of baking ovens;

(3) with the presoma that obtains under the protection of inert gas in 400 ℃ of-550 ℃ of sintering 5-8h, be finished product Li after the cooling ₃V ₂(PO ₄) ₃

Described chelating agent with reproducibility is a kind of in ascorbic acid, adipic acid, malonic acid and the citric acid, and the consumption of ascorbic acid, adipic acid, malonic acid and citric acid is 0.09-0.11mol;

Described lithium salts is a kind of in lithium acetate and the lithium nitrate, and the consumption of lithium acetate and lithium nitrate is 0.28-0.32mol;

Described phosphate is a kind of in ammonium dihydrogen phosphate, diammonium hydrogen phosphate and the triammonium phosphate, and the consumption of ammonium dihydrogen phosphate, diammonium hydrogen phosphate and triammonium phosphate is 0.28-0.32mol;

Described inert gas is a kind of in nitrogen and the argon gas.

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