CN101252187A - Method for low temperature preparing lithium ion battery positive pole material phosphoric acid vanadium lithium - Google Patents

Abstract

The invention discloses a method for preparing anode material vanadium lithium phosphate of a lithium-ion cell at low temperature, comprising the steps of: (1) heating vanadic oxide powder to six hundred to nine hundred DEG C; allowing to melt at a constant temperature for one to four hours and pouring into a container with water rapidly to form a brown-red solution; letting the solution stand for four to sixteen hours to form wet gel V2O5.nH2O; washing the wet gel, removing most of moisture, keeping drying for four to sixteen hours in a vacuum ambient of seventy to one hundred DEG C and grinding to obtain vanadic oxide powder. (2) Mixing the vanadic oxide powder obtained through the preparation method with lithium, phosphates and acetylene black evenly at mol ratio of one to three to three to three point six, sintering for ten to forty hours at temperature between four hundred to seven hundred DEG C under the protection of an inert gas and cooling to obtain a finished product of Li3V2 (PO4)3.The preparation method solves the problem that vanadium ion is easy to be oxidized, reduces sintering temperature and cost, improves the charging and discharging performance and cycle performance of samples.

Description

A kind of method of low temperature preparing lithium ion battery positive pole material phosphoric acid vanadium lithium

Technical field

The present invention relates to a kind of method of low temperature preparing lithium ion battery positive pole material phosphoric acid vanadium lithium.

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.Bibliographical information synthesizes Li at present ₃V ₂(PO ₄) ₃Material mainly adopts hydrogen reduction method and pyrocarbon thermal reduction.Hydrogen reduction method is owing to adopt pure H ₂As reducing agent, when experimental implementation because H ₂Inflammable and explosive character and very dangerous, be unfavorable for suitability for industrialized production.And shortcoming such as the skewness of institute's synthetic material particle diameter and electric conductivity be low.The pyrocarbon thermal reduction since the reaction temperature that needs than higher, thereby the material particle size skewness, electric conductivity and the cycle performance that are synthesized are bad.

Summary of the invention

The object of the present invention is to provide a kind of employing low temperature preparing lithium ion battery positive pole material Li ₃V ₂(PO ₄) ₃Method.To solve the easy oxidation of vanadium ion, to make that institute's synthetic material particle size distribution is even, tiny, conductivity improves, reduce sintering temperature, reduce cost, improved the chemical property of sample, simplified technology, make it to be easy to industrialized purpose.

Technical scheme of the present invention may further comprise the steps:

(1) vanadium pentoxide powder is heated to 600～900 ℃, and constant temperature 1～4h makes to pour into rapidly in the container that water is housed after its melting and form brown-red solution, this solution left standstill 4～16h can form V ₂O ₅NH ₂The O wet gel.With removing most of moisture after the wet gel washing,, grind and obtain the pentoxide gel powder then at 70～100 ℃ of following vacuumize 4～16h.

(2) be 1: 3: 3 in molar ratio with the above-mentioned pentoxide gel powder for preparing and lithium salts, phosphate, acetylene black: 3.6 mix after, under the protection of inert gas, in 400 ℃～700 ℃ sintering 10～40h, be finished product Li after the cooling ₃V ₂(PO ₄) ₃

Described lithium salts is a kind of in lithium acetate, lithium chloride, lithium nitrate and the lithium fluoride.

Described phosphate is a kind of in ammonium dihydrogen phosphate, diammonium hydrogen phosphate, potassium phosphate and the sodium phosphate.

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

The present invention directly uses the pentavalent vanadium to make raw material, has solved the easy problem of oxidation of vanadium ion; Reduced sintering temperature, can suppress too growing up of sample crystal grain effectively, made that institute's synthetic material particle size distribution is even, tiny, conductivity improves; Adjustable between 500～800 ℃ of the synthesis temperatures, can obtain varigrained material; Method is simple and convenient, be easy to control; The charge-discharge performance of sample and cycle performance improve, and have reduced cost.

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 0.1mol vanadium pentoxide powder is heated to 600 ℃, and constant temperature 4h makes to pour into rapidly in the container that water is housed after its melting and form brown-red solution, this solution left standstill 16h can form V ₂O ₅NH ₂The O wet gel.With removing most of moisture after the wet gel washing, at 70 ℃ of lower vacuum drying 16h, obtain the pentoxide gel powder after the grinding then.With the pentoxide gel powder of preparation with after 0.3mol lithium acetate, 0.3mol diammonium hydrogen phosphate and 0.36mol acetylene black mixes, under the protection of nitrogen, respectively at 500 ℃, 600 ℃, 700 ℃, 800 ℃ sintering 10h, 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 1 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 50 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 50th discharge capacity/mAhg -1
						1	500	10	110	91	55
2	600	10	128	120	101
						3	700	10	130	125	112
4	800	10	127	116	103

Embodiment 2:

The 0.1mol vanadium pentoxide powder is heated to 900 ℃, and constant temperature 1h makes to pour into rapidly in the container that water is housed after the vanadic anhydride melting and form brown-red solution, this solution left standstill 12h can form V ₂O ₅NH ₂The O wet gel.With removing most of moisture after the wet gel washing, at 90 ℃ of lower vacuum drying 12h, obtain the pentoxide gel powder after the grinding then.With the pentoxide gel powder of preparation with after 0.3mol lithium fluoride, 0.3mol ammonium dihydrogen phosphate (ADP) and 0.36mol acetylene black mixes, under the protection of argon gas, in 700 ℃ of sintering 10,20,30 and 40h 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 1 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 50 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 50th discharge capacity/mAhg -1
						1	700	10	120	100	78
2	700	20	125	114	90
						3	700	30	115	100	76
4	700	40	114	95	45

Embodiment 3:

The 0.1mol 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 form brown-red solution, this solution left standstill 4h can form V ₂O ₅NH ₂The O wet gel.With removing most of moisture after the wet gel washing,, grind and obtain the pentoxide gel powder then at 100 ℃ of following vacuumize 8h.With the pentoxide gel powder of preparation with after 0.3mol lithium chloride, 0.3mol potassium phosphate and 0.36mol acetylene black mixes, under the protection of argon gas, in respectively at 550 ℃, 650 ℃, 750 ℃, 800 ℃ sintering 40h, 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 1 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 50 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 50th discharge capacity/mAhg -1
						1	550	40	103	90	68
2	650	40	118	95	77
						3	750	40	130	110	93
4	800	40	106	79	34

Embodiment 4:

The 0.1mol vanadium pentoxide powder is heated to 700 ℃, and constant temperature 3h makes to pour into rapidly in the container that water is housed after its melting and form brown-red solution, this solution left standstill 8h can form V ₂O ₅NH ₂The O wet gel.With removing most of moisture after the wet gel washing,, grind and obtain the pentoxide gel powder then at 80 ℃ of following vacuumize 4h.After prepared pentoxide gel powder and 0.3mol lithium nitrate, 0.3mol sodium phosphate and 0.36mol acetylene black mixed, under the protection of nitrogen, in 650 ℃ of respectively sintering 8,18,28,38h, 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 1 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 50 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 50th specific discharge capacity/mAhg -1
						1	650	8	120	99	65
2	650	18	125	106	84
						3	650	28	129	111	90
4	650	38	116	102	78

Claims (1)

1. the method for a low temperature preparing lithium ion battery positive pole material phosphoric acid vanadium lithium is characterized in that concrete steps are:

(1) vanadium pentoxide powder is heated to 600～900 ℃, and constant temperature 1～4h makes to pour into rapidly in the container that water is housed after its melting and form brown-red solution, this solution left standstill 4～16h can form V ₂0 ₅NH ₂The O wet gel; With removing most of moisture after the wet gel washing, then at 70～100 ℃ of lower vacuum drying 4～16h, grind and obtain the pentoxide gel powder;

(2) be 1: 3: 3 in molar ratio with the above-mentioned pentoxide gel powder for preparing and lithium salts, phosphate, acetylene black: 3.6 mix after, under the protection of inert gas, in 400 ℃～700 ℃ sintering 10～40h, be finished product Li after the cooling ₃V ₂(PO ₄) ₃

Described lithium salts is a kind of in lithium acetate, lithium chloride, lithium nitrate and the lithium fluoride; Described phosphate is a kind of in ammonium dihydrogen phosphate, diammonium hydrogen phosphate, potassium phosphate and the sodium phosphate; Described inert gas is a kind of in nitrogen and the argon gas.

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