Summary of the invention
The present invention seeks to overcome the problem that prior art exists, provide a kind of process route simple, be applicable to large-scale industrial production, for the preparation of the synthetic method of the high-specific surface area lithium phosphate of phosphate lithium ion anode material.
For the preparation of a synthetic method for the high-specific surface area lithium phosphate of phosphate lithium ion anode material, adopt following steps:
The first step, joins a certain amount of deionized water in the cooling retort of jacketed, and chuck passes into chilled water, keeps the interior temperature of retort lower than 10 DEG C, and strong stirring in retort, passes into N simultaneously in retort
2, the dissolved oxygen concentration in retort is reduced to below 0.05mg/L, slowly add lithium hydroxide, until lithium hydroxide dissolves completely;
The quality adding at the deionized water described in the first step and the mass ratio of lithium hydroxide are 8 ~ 30:1.
Second step, vacuumizes the retort of sealing, and carries out strong stirring, speed of agitator is 500 ~ 1000rpm, use droplet discharging head that certain density phosphoric acid solution is added from retort top, control the speed that adds of solution, reacted under rear normal pressure and left standstill more than 24 hours.
Be 50% ~ 5% at the phosphoric acid solution mass fraction described in second step, described vacuum ranges is-0.01MPa ~-0.1MPa, the diameter of the phosphoric acid drop that described droplet discharging head sprays is 0.01 ~ 20mm, described phosphoric acid solution adds the adjustable range of speed to be, ensures in retort that temperature of charge is lower than 10 DEG C.
The 3rd step, pumps supernatant liquor, and by dry remaining slurry spraying, baking temperature is 250 ~ 300 DEG C, and dried powder is carried out to air-flow crushing processing, finally obtains the lithium phosphate powder of high-specific surface area.
In the 3rd step, the pressure limit of air-flow crushing is 0.3 ~ 0.8MPa.
Adopt after such scheme, compared with prior art, characteristics and advantages is in the present invention:
(1) course of reaction control reaction temperature is less than 10 DEG C and carry out under negative pressure, and the condition of negative pressure and low temperature makes that synthetic lithium phosphate product granularity is little, specific area large, active high;
(2) first logical nitrogen of reaction, makes the gas concentration lwevel that dissolves in deionized water in retort very low, has suppressed the generation of lithium carbonate, and the product purity obtaining is very high;
(3) use droplet discharging head to add phosphoric acid solution, phosphoric acid solution can be reacted with lithium hydroxide equably, be conducive to generate the lithium phosphate of high-specific surface area;
(4) technical process is simple, easy to operate, does not introduce other impurity simultaneously, and product purity is high;
(5)the lithium phosphate precursor that utilizes the method to prepare, specific area can reach 200m
2/ g; Adopt the synthetic lithium ion anode material of this lithium phosphate aspect electrical property, to obtain significant raising.
Embodiment
Embodiment 1
In retort, add 3.5L deionized water, chuck leads to chilled water, keeps temperature in retort lower than 10 DEG C, to pass into while stirring nitrogen in retort.When dissolved oxygen amount is reduced to 0.05mg/L in question response tank, slowly add 9.0mol lithium hydroxide.After lithium hydroxide dissolves completely, retort to sealing vacuumizes, vacuum degree is-0.08MPa, strong stirring, speed of agitator is 900rpm, be that 8% phosphoric acid droplet discharging head slowly adds in retort by 3.0mol mass fraction, control and add speed, make in adition process that in retort, temperature can not be higher than 10 DEG C.After having reacted, stop stirring, and leave standstill more than 24 hours under normal pressure.Pump supernatant liquor, remaining slurry is spray-dried, and baking temperature is 300 DEG C, and dry rear powder carries out air-flow crushing processing, and pulverizing pressure is 0.6MPa, obtains the lithium phosphate powder of specific area.The specific area of synthetic lithium phosphate is 201.8m
2/ g.
Wherein Fig. 1 is the XRD figure for preparing lithium phosphate material, the scanning electron microscope (SEM) photograph of the prepared lithium phosphate material of Fig. 2.
Synthetic LiFePO
4/ C: synthetic lithium phosphate, 3.0mol ferrous sulfate, 10g ascorbic acid and 3.0L deionized water are joined in autoclave, 200 DEG C are incubated 3 hours, after cooling cleaning, add 50g glucose, the dry powder that forms of spraying, 750 DEG C of sintering obtain the coated LiFePO of carbon for 6 hours
4/ C material.
Synthetic LiMn
2/3fe
1/3pO
4/ C: synthetic lithium phosphate, 2.0mol manganese phosphate, 1.0mol ferrous sulfate, 10g ascorbic acid and 3.0L deionized water are joined in autoclave, 200 DEG C are incubated 3 hours, after cooling cleaning, add 50g glucose, the dry powder that forms of spraying, 750 DEG C of sintering obtain the coated LiMn of carbon for 6 hours
2/3fe
1/3pO
4/ C material.
Cell evaluation: by the material preparing, conductive agent acetylene black and binding agent PVDF in mass ratio for 75:15:10 is made into positive plate, adopt coin shape simulated battery to carry out battery assembling to prepared electrode slice, be wherein metal lithium sheet to electrode, barrier film is Celgard2325 composite membrane.The button cell of making is 0.1C(1C=170mAh/g in 2.5 ~ 4.5V voltage range) constant current charge-discharge test.
Table 1 has been listed the capacity of the battery of doing.
Embodiment 2
In retort, add 3.5L deionized water, the obstructed chilled water of chuck, passes into nitrogen while stirring in retort.When dissolved oxygen amount is reduced to 0.05mg/L in question response tank, slowly add 9.0mol lithium hydroxide.After lithium hydroxide dissolves completely, the retort of sealing is vacuumized, vacuum degree is-0.05MPa, strong stirring, speed of agitator is 900rpm, is that 8% phosphoric acid droplet discharging head adds in retort by 3.0mol mass fraction, and in course of reaction, in retort, temperature is up to 45 DEG C.After having reacted, stop stirring, and leave standstill more than 24 hours under normal pressure.Pump supernatant liquor, remaining slurry is spray-dried, and baking temperature is 300 DEG C, and dry rear powder carries out air-flow crushing processing, and pulverizing pressure is 0.6MPa, obtains the lithium phosphate powder of specific area.The specific area of synthetic lithium phosphate is 79.6m
2/ g.
By the method for embodiment 1, synthetic lithium phosphate is made to LiFePO
4/ C and LiMn
2/3fe
1/3pO
4/ C.And be made into button electricity, discharge and recharge with 0.1C.
1 contrast is found with embodiment, and when obstructed cooling water, reaction temperature rises, and the BET value of synthetic lithium phosphate is very little.The capacity of making battery after synthetic phosphate cathode material also reduces.
Embodiment 3
In retort, add 3.5L deionized water, the obstructed chilled water of chuck, passes into nitrogen while stirring in retort.When dissolved oxygen amount is reduced to 0.05mg/L in question response tank, slowly add 9.0mol lithium hydroxide.After lithium hydroxide dissolves completely, the retort of sealing is vacuumized, vacuum degree is-0.08MPa, strong stirring, speed of agitator is 900rpm, is that 8% phosphoric acid is directly poured in retort by 3.0mol mass fraction, and in course of reaction, in retort, temperature is up to 50 DEG C.After having reacted, stop stirring, and leave standstill more than 24 hours under normal pressure.Pump supernatant liquor, remaining slurry is spray-dried, and baking temperature is 300 DEG C, and dry rear powder carries out air-flow crushing processing, and pulverizing pressure is 0.6MPa, obtains the lithium phosphate powder of specific area.The specific area of synthetic lithium phosphate is 36.0m
2/ g.
By the method for embodiment 1, synthetic lithium phosphate is made to LiFePO
4/ C and LiMn
2/3fe
1/3pO
4/ C.And be made into button electricity, discharge and recharge with 0.1C.
2 contrasts are found with embodiment, and when obstructed cooling water, do not adopt droplet discharging head, reaction temperature rises higher, and the BET value of synthetic lithium phosphate is less.The capacity of making battery after synthetic phosphate cathode material is also lower.
Embodiment 4
In retort, add 3.5L deionized water, chuck leads to chilled water, keeps temperature in retort lower than 10 DEG C, to pass into while stirring nitrogen in retort.When dissolved oxygen amount is reduced to 0.05mg/L in question response tank, slowly add 9.0mol lithium hydroxide.After lithium hydroxide dissolves completely, strong stirring, speed of agitator is 900rpm, is that 8% phosphoric acid droplet discharging head slowly adds in retort by 3.0mol mass fraction, controls and adds speed, makes in adition process that in retort, temperature can not be higher than 10 DEG C.After having reacted, stop stirring, leave standstill more than 24 hours.Pump supernatant liquor, remaining slurry is spray-dried, and baking temperature is 300 DEG C, and dry rear powder carries out air-flow crushing processing, and pulverizing pressure is 0.6MPa, obtains the lithium phosphate powder of specific area.The specific area of synthetic lithium phosphate is 160.2m
2/ g.
By the method for embodiment 1, synthetic lithium phosphate is made to LiFePO
4/ C and LiMn
2/3fe
1/3pO
4/ C.And be made into button electricity, discharge and recharge with 0.1C.
1 contrast is found with embodiment, and reaction is not vacuumizing under condition of negative pressure, and the BET value of synthetic lithium phosphate is less.The capacity of making battery after synthetic phosphate cathode material decreases.
Embodiment 5
In retort, add 3.5L deionized water, chuck leads to chilled water, keeps temperature in retort lower than 10 DEG C, to start to stir, and add 9.0mol lithium hydroxide in retort.After lithium hydroxide dissolves completely, strong stirring, speed of agitator is 900rpm, is that 8% phosphoric acid droplet discharging head slowly adds in retort by 3.0mol mass fraction, controls and adds speed, makes in adition process that in retort, temperature can not be higher than 10 DEG C.After having reacted, stop stirring, leave standstill more than 24 hours.Pump supernatant liquor, remaining slurry is spray-dried, and baking temperature is 300 DEG C, and dry rear powder carries out air-flow crushing processing, and pulverizing pressure is 0.6MPa, obtains the lithium phosphate powder of specific area.The specific area of synthetic lithium phosphate is 149.5m
2/ g.
By the method for embodiment 1, synthetic lithium phosphate is made to LiFePO
4/ C and LiMn
2/3fe
1/3pO
4/ C.And be made into button electricity, discharge and recharge with 0.1C.
1 contrast is found with embodiment, the obstructed nitrogen of course of reaction, and the BET value of synthetic lithium phosphate is less.The capacity of making battery after synthetic phosphate cathode material decreases.
Embodiment 6
In retort, add 3.5L deionized water, chuck leads to chilled water, keeps temperature in retort lower than 10 DEG C, to pass into while stirring nitrogen in retort.When dissolved oxygen amount is reduced to 0.05mg/L in question response tank, slowly add 9.0mol lithium hydroxide.After lithium hydroxide dissolves completely, retort to sealing vacuumizes, vacuum degree is-0.08MPa strong stirring, speed of agitator is 900rpm, be that 50% phosphoric acid droplet discharging head slowly adds in retort by 3.0mol mass fraction, control adds speed, makes in adition process that in retort, temperature can not be higher than 10 DEG C.After having reacted, stop stirring, and leave standstill more than 24 hours under normal pressure.Pump supernatant liquor, remaining slurry is spray-dried, and baking temperature is 300 DEG C, and dry rear powder carries out air-flow crushing processing, and pulverizing pressure is 0.6MPa, obtains the lithium phosphate powder of specific area.The specific area of synthetic lithium phosphate is 190.1m
2/ g.
By the method for embodiment 1, synthetic lithium phosphate is made to LiFePO
4/ C and LiMn
2/3fe
1/3pO
4/ C.And be made into button electricity, discharge and recharge with 0.1C.
1 contrast is found with embodiment, and the mass fraction of phosphoric acid is increased to 50%, and the BET value of synthetic lithium phosphate is less, but still is the lithium phosphate of high-specific surface area.The capacity of making battery after synthetic phosphate cathode material is also very high.
The lithium phosphate BET value that table 1 embodiment 1-6 is synthetic and the specific capacity of synthesized phosphate cathode material