A kind of thermal cell modified lithium boron alloy composite negative pole material and preparation method thereof[technical field]
The invention belongs to thermal cell technical fields, and in particular to a kind of modified lithium boron alloy composite negative pole material of thermal cellAnd preparation method thereof.
[background technique]
Thermal cell is to make electrolyte with fused salt, and a reserve cell of its fusing and activation is made using heat source.Since it hasThere is the features such as very high specific energy and specific power, use environment temperature is wide, period of storage is long, activation is reliable rapidly, is guided missile, fireThe ideal source of the sophisticated weapons such as big gun.
Lithium boron alloy has been developed in recent years novel Thermal Cell Cathode Material, and structure is heat-resisting stephanoporate framework lithium boronThe double structure of free Li is adsorbed in compound, therefore its chemical property and pure Li are close, and because of the absorption of LiB compoundEffect can keep free Li not spill at 600 DEG C, meet 500 DEG C of thermal cell or so of temperature requirement.Lithium boron alloy hasThe advantages that specific capacity is high, and high power performance is good.But lithium boron alloy thermal cell is at low-temperature high-current discharge initial stage, due in thermal cellPortion's temperature is lower, and electrolyte can not completely be infiltrated with the free lithium in lithium boron alloy, and the free lithium in part is not in anode reactionLithium ion can be smoothly converted into and entered in electrolyte, concentration polarization is generated, macro manifestations go out the recessed peak of voltage, can only lead at presentThe mode of increase thermal design is crossed to be solved, which will affect the safety of battery and reduce the ratio characteristic of battery, becauseThere is an urgent need to solve the problems, such as this in terms of lithium boron alloy material for this.
[summary of the invention]
The object of the invention is that providing a kind of modified lithium boron alloy of thermal cell to solve the deficiencies in the prior artComposite negative pole material and preparation method thereof.
On the one hand, the present invention provides a kind of modified lithium boron alloy composite negative pole materials of thermal cell, by weight percentage,Its is composed of the following components for the modified lithium boron alloy composite negative pole material:
Li7B6Phase 41-69wt%；
Lithium magnesium sosoloid phase 25-55wt%；And
Ionic conductive agent phase 1-15wt%.
Preferably, by weight percentage, it is to be prepared from the following materials:
Preferably, the ionic conductive agent is identical as thermal battery electrolyte conductive compositions, for selected from LiCl-KCl binary salt,The binary of VII race element lithium salts and other inorganic salts of VII race element composition in LiBr-LiCl-LiF ternary salt, the periodic table of elementsOr polybasic salt is any,
The binary or polybasic salt of VII race element lithium salts and other inorganic salts of VII race element composition in the periodic table of elementsIt is preferably LiI-KI binary salt, LiBr-CsCl binary salt, LiBr-CsBr binary salt, LiCl-RbCl binary salt, LiBr-KBr-LiF ternary salt, CsBr-LiBr-KBr ternary salt, RbCl-LiCl-KCl ternary salt, LiBr-RbBr binary salt or LiCl-KCl-CaCl2One of ternary salt.
On the other hand, the preparation method for being modified lithium boron alloy composite negative pole material is used the present invention provides a kind of thermal cell,The following steps are included:
S1. ionic conductive agent is melted to obtain the first melt；
S2. molten metal lithium, boron and magnesium metal are mixed to obtain the second melt；
S3. the first melt is added in the second melt of stirring to obtain blend melt；
S4. by blend melt temperature reaction until generating LiB compound skeleton obtains solid alloy.
Preferably, the method carries out in an inert gas atmosphere；The inert gas atmosphere contains with the water of < 1ppmThe oxygen content of amount and < 10ppm.
Preferably, the step S1 is carried out within the temperature range of 400-500 DEG C, and the step S2 is at 250-400 DEG CIt is carried out in temperature range, the step S3 stirring rate >=1000r/min.
Preferably, lithium metal is first molten into lithium liquid by the step S2, and then boron and magnesium metal are added in lithium liquid, chargingWhen lithium liquid temperature be 250-400 DEG C, boron need to feed in batches, each charge weight be no more than all raw material gross weights 10wt%,Feed time interval is not less than 5min, add after forming uniform second melt, continues the temperature of the second melt of raising to 400-500 DEG C, make the temperature difference of the second melt and the first melt within 10 DEG C, then, just can be carried out the mixing of two kinds of melts.
Preferably, the step S3 is warming up to 500- by blend melt with the heating rate in the range of 1-5 DEG C/min550 DEG C, until reaction obtains solid alloy, fusion process terminates.
Preferably, the step S3 is obtained continuing extrusion blooming after solid alloy, is rolled into band.
On the other hand, present invention also provides a kind of thermal cell, cathode is multiple using modified lithium boron alloy as described aboveNegative electrode material is closed to be made.
The modified lithium boron alloy composite negative pole material of thermal cell provided by the invention, the modification lithium boron alloy are pre- inside itIt is first added to ionic conductive agent, and this ionic conductive agent is consistent with conductive compositions in the matching used electrolyte of thermal cell, asWhen thermal cell negative electrode material, thermal cell low-temperature high-current discharge initial stage electrolyte and the wellability of free lithium are good, can promote electricityPole reaction rate improves the recessed peak of voltage.In thermal cell discharge process, in lithium boron alloy dissociate lithium can be shifted into electrolyte andHole is formed in lithium boron alloy, electrolyte can be filled into lithium boron alloy hole, when two kinds of material wellability differences, electrolysisMatter filling hole is slow, will lead to polarization and generates.And it is added to the lithium boron alloy of ionic conductive agent in advance, it is identical because having in alloyIngredient, it is easier to infiltrate, charging efficiency is higher, can promote electrode reaction efficiency.
The preparation method of above-mentioned modified lithium boron alloy composite negative pole material provided by the invention, it is mixed using Double liquid state modeIt closes, can uniformly disperse ionic conductive agent in inside solid lithium boron alloy, this method preparation process is simple, solves ionThe problem of conductive agent and lithium boron alloy later period can not be using mechanical means mixing.
[Detailed description of the invention]
Fig. 1 is lithium boron alloy composite negative pole material X-ray diffraction object phase map provided by the invention.
Fig. 2 is reaction unit schematic diagram of the present invention.
Fig. 3 is the low temperature 20A constant-current discharge comparison that the modification lithium boron alloy that embodiment 1 obtains is obtained as battery cathode sheetTest Drawing.
Fig. 4 is the low temperature 20A constant-current discharge comparison that the modification lithium boron alloy that embodiment 2 obtains is obtained as battery cathode sheetTest Drawing.
Fig. 5 is the low temperature 13A constant-current discharge test that the modification lithium boron alloy that comparative example 3 obtains is obtained as battery cathode sheetFigure.
[specific embodiment]
The invention will be further described with embodiment with reference to the accompanying drawing.
The present invention provides a kind of modified lithium boron alloy composite negative pole materials of thermal cell, by Li7B6Phase, the solid solution of lithium magnesiumBody phase and ionic conductive agent phase composition, wherein Li7B6The 41-69wt% of modified lithium boron alloy composite negative pole material is mutually accounted for, lithium magnesium is solidSolution mutually accounts for the 25-55wt% of modified lithium boron alloy composite negative pole material, and ionic conductive agent mutually accounts for modified lithium boron alloy and answersThe 1-15wt% of negative electrode material is closed, ionic conductive agent is identical as thermal battery electrolyte conductive compositions, and what is obtained according to the present invention changesProperty lithium boron alloy be silver gray soft metal material.
Studies have shown that the very few electrical property for alloy, which is added, in ionic conductive agent improves unobvious, ionic conductive agent additionExcessively, alloy capacitance loss is caused, in addition alloy can become fragile, and difficulty of processing increases.A certain amount of magnesium metal is added can be with lithiumLithium magnesium sosoloid phase is formed, compared with pure lithium, fusing point is improved, and mobility reduces, and improves the high-temperature stability of alloy.
The modification lithium boron alloy composite negative pole material is added to and conduction in matching used electrolyte in advance inside itThe consistent ionic conductive agent of ingredient, when as thermal cell negative electrode material, thermal cell low-temperature high-current discharge initial stage electrolyte withThe infiltration of free lithium is good, can promote electrode reaction rate, improves the recessed peak of voltage.The modification lithium boron alloy composite negative pole materialX-ray diffraction object phase map is as shown in Figure 1.From fig. 1, it can be seen that alloy is Li7B6Phase, lithium magnesium phase and ionic conductive agent three-phase structure.
Above-mentioned thermal cell can be used following raw material with modified lithium boron alloy composite negative pole material by weight percentage and prepareIt forms: lithium metal 52-68wt%, magnesium metal 1-6wt%, boron 25-38wt%, ionic conductive agent 1-15wt%.Lithium metal, metalChemical materials can be selected in magnesium, boron, wherein it is preferred that lithium metal purity >=99.9%, state can be lithium ingot, lithium grain, lithium band；Magnesium metalPurity >=99%, state can be magnesium grain, magnesium powder；Boron purity >=97%, state are powder.LiCl-KCl can be selected in ionic conductive agentVII race element lithium salts and VII race element other inorganic salts groups in binary salt, LiBr-LiCl-LiF ternary salt or the periodic table of elementsAt binary or polybasic salt, can be specially LiI-KI binary salt, LiBr-CsCl binary salt, LiBr-CsBr binary salt, LiCl-RbCl binary salt, LiBr-KBr-LiF ternary salt, CsBr-LiBr-KBr ternary salt, RbCl-LiCl-KCl ternary salt, LiBr-RbBr binary salt or LiCl-KCl-CaCl2One of ternary salt.
The preparation method of the modified lithium boron alloy composite negative pole material of thermal cell of the present invention, comprising the following steps:
S1. ionic conductive agent is melted to obtain the first melt；
S2. it will melt, mixed to obtain the second melt comprising the raw material of lithium metal, magnesium metal and boron；
S3. the first melt is added to obtain blend melt in the second melt of stirring, wherein it is molten to account for mixing for lithium metalThe 52-68wt% of body, magnesium metal account for the 1-6wt% of blend melt, and boron powder accounts for blend melt 25-38wt%, and ionic conductionAgent accounts for the 1-15wt% of blend melt；
S4. by blend melt temperature reaction until generating LiB compound skeleton obtains solid alloy, which isSilver gray soft metal material.
In above-mentioned preparation method, as the first melt ionic conductive agent and include molten metal lithium, magnesium metal and boronThe second melt mixed in a manner of Double liquid state in fusion process, it is ensured that the even dispersion of ionic conductive agent.Under room temperature, ionConductive agent is powder, and lithium boron alloy is solid block, and powder can not be made, and is difficult uniformly to mix.The method of the present invention uses biliquidState mode mixes, and solves the problems, such as that ionic conductive agent and lithium boron alloy later period can not be mixed using mechanical means.And it can be into oneStep controls its mixing temperature, prevents the too low ionic conductive agent of temperature from solidifying blocking influence mixed effect, while preventing temperature excessively highCause the reaction of explosion type, while the second melt will carry out strong stirring in ionic conductive agent adition process, stirring rate >=1000r/min.The ionic conductive agent of the first melt by optimization and second molten comprising molten metal lithium, magnesium metal and boronThe melting mixing step of body are as follows:
It is spare that ionic conductive agent is molten into the first melt within the temperature range of 400-500 DEG C, then first by lithium metalIt being molten into lithium liquid, then boron and magnesium metal is added in lithium liquid, lithium liquid temperature is 250-400 DEG C when charging, and boron need to feed in batches,Each charge weight is no more than the 10wt% of all raw material gross weights, and feed time interval is not less than 5min, and addition forms well uniformAfter second melt, the temperature for continuing to increase the second melt makes the temperature difference of the second melt and the first melt at 10 DEG C to 400-500 DEG CWithin, then, it just can be carried out the mixing of two kinds of melts.Boron can be in contact reaction after lithium liquid is added, and solution temperature can increase, such asLocal temperature will not generally cause explosion type reaction within 500 DEG C, and for safety, it is as small as possible to control solution temperature rise, excellentBoron is added in choosing in batches, and the heat of generation can quickly scatter and disappear, if 5-8 batch is divided to be added, solution temperature rise can be protected within 20 DEG CCard will not cause explosion type reaction.
When high temperature, lithium metal is easy to react with oxygen, nitrogen, the vapor etc. in air, therefore prepared by the present inventionThe preferred entirety of method carries out in an inert gas atmosphere, prevents lithium metal from reacting with oxygen, vapor, reduces in alloyLi2The oxygen of the impurity contents such as O, LiOH, water content and < 10ppm of the further preferred inert gas atmosphere with < 1ppm containsAmount.
Blend melt is preferably warming up to 500-550 DEG C with the heating rate in the range of 1-5 DEG C/min by above-mentioned steps S3,Solid alloy being obtained to reaction, limitation heating rate is 1-5 DEG C/min, it is ensured that reaction is more abundant, but can not be excessively slow,Influence efficiency.
After obtaining solid alloy, extrusion blooming can be continued through to its cooling, is rolled into spare；It can also be further through rushingIt is pressed into thermal cell cathode disk.
Preparation method of the present invention can carry out in device as shown in Figure 2.Preparation method can specifically use following steps:Oxygen content < 0.1ppm in water content < 10ppm glove box, ionic conductive agent is put into the first Iron reutilization 1, by the first ironyCrucible 1 is put into the tube furnace 2 of inclined rotating, and being warming up to 400-500 DEG C melts ionic conductive agent, and melt temperature control is existedThe temperature, this is the first melt 3.Lithium metal is put into the second Iron reutilization 4, the second Iron reutilization 4 is put into well formula electricityIt hinders in furnace 6, being warming up to 250-400 DEG C melts lithium metal, installs stirring rod 5, strong stirring is carried out, by boron powder, magnesium metal grainIt is added in lithium liquid, is maintained at 250-400 DEG C and continues to stir 1h or more, then heat to 400-500 DEG C, make the second melt and theThe temperature difference of one melt controls within 10 degree in the temperature, this is the second melt 7.
Second the first melt 3 in the first Iron reutilization 1 in rotary tube furnace 2 is added in well formula resistance furnace 6In second melt 7 of the strong stirring in Iron reutilization 4, and it is maintained at 400-500 DEG C of stirring 1h or more.
Stop stirring, furnace temperature to liquid reactions are increased with the speed of 1-5 DEG C/min and generate solid alloy ingot.
Above-mentioned apparatus topology layout is reasonable, can meet needed for present invention preparation.
Embodiment 1
In oxygen content < 0.1ppm, water content 1.8ppm glove box, by the LiCl-KCl binary salt as ionic conductive agent30g (wherein LiCl is 45wt%, KCl 55wt%) is put into the first Iron reutilization, which is put into tiltable rotationThe tube furnace turned, being warming up to 420 DEG C melts ionic conductive agent, and by melt temperature control in the temperature, this is molten for firstBody.By lithium metal 659.6g, it is put into the second Iron reutilization, which is put into well formula resistance furnace, being warming up to 250 DEG C makesLithium metal fusing, installs stirring rod, carries out strong stirring, mixing speed 1000r/min, by boron powder 252.2g average mark by weightIt is 5 parts, interval 10min adds portion into lithium liquid, until adding, then is spaced 10min and magnesium metal grain 58.2g is added at one time lithiumIt in liquid, is maintained at 250 DEG C ± 10 DEG C and stirs 2h, then heat to 420 DEG C and control in the temperature, this is molten for secondBody.
The first melt in the first crucible in rotary tube furnace is added in the second crucible in well formula resistance furnaceIn second melt of strong stirring, and it is maintained at 420 DEG C of ± 5 DEG C of stirring 2h.
Stop stirring, furnace temperature is increased to 520 DEG C with the speed of 3 DEG C/min, liquid reactions generate solid alloy ingot.It has reactedLi is obtained by theoretical calculation under the conditions of complete7B6Mutually account for the 44.92wt% of modified lithium boron alloy composite negative pole material, the solid solution of lithium magnesiumBody mutually accounts for the 52.08wt% of modified lithium boron alloy composite negative pole material, and ionic conductive agent mutually accounts for modified lithium boron alloy composite negative poleThe 3wt% of material.
Alloy pig after cooling takes out from crucible in -43 DEG C of dew point of drying shed, removes Surface Oxygen using abrasive machineChange skin, 5mm band is squeezed into using Form-bar Press Machine, using double roller roll forming machine be rolled into 0.6mm strip (be pressed into every time ratio <20%), then stamped machine is washed into the disk of diameter 58mm.
It is anode (anode is excessive), LiCl- using conventional lithium boron alloy piece and modified lithium boron alloy piece as cathode, cobalt disulfideKCl-MgO is that electrolyte is assembled into thermal cell, stands 6 hours in -40 DEG C of cryogenic boxes, then takes out and carry out 20A constant-current dischargeComparative test, test result is as shown in figure 3, as can be seen from Figure 3, the modification lithium boron alloy piece obtained using the present embodiment is relative to normalLithium boron alloy piece is advised, the recessed peak of voltage early period has clear improvement (voltage die is caused by pulse current in figure).
Embodiment 2
In oxygen content < 0.1ppm, the glove box of water content 1.0ppm, by the LiBr-LiCl- as ionic conductive agentLiF ternary salt 90g (wherein LiBr68wt%, LiCl22wt%, LiF 10wt%) is put into the first Iron reutilization, by the ironyCrucible is put into the tube furnace of inclined rotating, and being warming up to 480 DEG C melts ionic conductive agent, and melt temperature is controlled in the temperatureHeat preservation, this is the first melt.By lithium metal 546g, it is put into the second Iron reutilization, which is put into well formula resistance furnace,Being warming up to 300 DEG C melts lithium metal, installs stirring rod, carries out strong stirring, mixing speed 1000r/min, by boron powder327.6g is equally divided into 6 parts by weight, and interval 10min adds portion into lithium liquid, until adding, then is spaced 10min for magnesium metalGrain 36.4g is added at one time in lithium liquid, is maintained at 300 DEG C ± 10 DEG C and is stirred 3h, is then heated to 480 DEG C and is controlled in the temperatureDegree heat preservation, this is the second melt.
The first melt in the first crucible in rotary tube furnace is added in the second crucible in well formula resistance furnaceIn second melt of strong stirring.
Stop stirring, furnace temperature is increased to 520 DEG C with the speed of 2 DEG C/min, liquid reactions generate solid alloy ingot.It has reactedThe Li obtained under the conditions of complete by theoretical calculation7B6Mutually account for the 57.3wt% of modified lithium boron alloy composite negative pole material, the solid solution of lithium magnesiumBody mutually accounts for the 33.7wt% of modified lithium boron alloy composite negative pole material, and ionic conductive agent mutually accounts for modified lithium boron alloy composite negative pole materialThe 9wt% of material.
For verifying alloy in lithium boron object phase, lithium magnesium phase, ionic conductive agent three-phase be distributed uniformity coefficient, respectively alloy not5 sample test lithiums, content of magnesium are taken with position, test uses inductively coupled plasma atomic emission spectrometer (ICP-AES),Test result is shown in Table 1, and because the theoretical lithium content of lithium boron object phase in alloy is 39.1wt%, theoretical lithium content is in lithium magnesium sosoloid80-90wt%, theoretical lithium content < 12wt% of ionic conductive agent phase, the lithium content difference of each phase structure is larger, and in table 1Statistics indicate that, the lithium content and content of magnesium consistency of 5 groups of samples are preferable, therefore, can estimate each mutually evenly dispersed in alloy.
The lithium content and content of magnesium of 1. sample of table
| Sample number into spectrum | Lithium content % | Content of magnesium % |
| 1# | 56.02 | 3.72 |
| 2# | 56.10 | 3.70 |
| 3# | 55.93 | 3.71 |
| 4# | 56.02 | 3.71 |
| 5# | 55.99 | 3.71 |
| Standard deviation | 0.061 | 0.007 |
Alloy pig after cooling takes out from crucible in -45 DEG C of dew point of drying shed, removes Surface Oxygen using abrasive machineChange skin, 5mm band is squeezed into using Form-bar Press Machine, using double roller roll forming machine be rolled into 0.6mm strip (be pressed into every time ratio <20%), then stamped machine is washed into the disk of diameter 58mm.
It is anode (anode is excessive), LiBr- using conventional lithium boron alloy piece and modified lithium boron alloy piece as cathode, cobalt disulfideLiCl-LiF+MgO is that electrolyte is assembled into thermal cell, stands 6 hours in -40 DEG C of cryogenic boxes, then takes out and carry out 20A constant currentElectric discharge comparative test, test result is as shown in figure 4, as can be seen from Figure 4, the modification lithium boron alloy piece obtained using the present embodiment is oppositeIn conventional lithium boron alloy piece, the recessed peak of voltage early period has clear improvement (voltage die is caused by pulse current in figure).
Embodiment 3
In oxygen content < 0.1ppm, water content 1.8ppm glove box, by the LiCl-KCl binary salt as ionic conductive agent55g (wherein LiCl is 45wt%, KCl 55wt%) is put into the first Iron reutilization, which is put into tiltable rotationThe tube furnace turned, being warming up to 450 DEG C melts ionic conductive agent, and by melt temperature control in the temperature, this is molten for firstBody.By lithium metal 600g, it is put into the second Iron reutilization, which is put into well formula resistance furnace, being warming up to 350 DEG C makes goldBelong to lithium fusing, stirring rod is installed, carry out strong stirring, boron powder 310g is equally divided into 5 by mixing speed 1000r/min by weightPart, interval 8min adds portion into lithium liquid, until adding, then is spaced 8min and magnesium metal grain 35g is added at one time in lithium liquid, protectsIt holds at 350 DEG C ± 10 DEG C and stirs 2h, then heat to 450 DEG C and control in the temperature, this is the second melt.
The first melt in the first crucible in rotary tube furnace is added in the second crucible in well formula resistance furnaceIn second melt of strong stirring, and it is maintained at 450 DEG C of ± 5 DEG C of stirring 2h.
Stop stirring, furnace temperature is increased to 540 DEG C with the speed of 4 DEG C/min, liquid reactions generate solid alloy ingot.It has reactedThe Li obtained under the conditions of complete by theoretical calculation7B6The 54.22wt% of modified lithium boron alloy composite negative pole material is mutually accounted for, lithium magnesium is solidSolution mutually accounts for the 40.28wt% of modified lithium boron alloy composite negative pole material, and ionic conductive agent mutually accounts for modified lithium boron alloy Compound NegativeThe 5.5wt% of pole material.
Embodiment 4
In oxygen content < 0.1ppm, water content 1.8ppm glove box, by the LiCl-KCl binary salt as ionic conductive agent20g (wherein LiCl is 45wt%, KCl 55wt%) is put into the first Iron reutilization, which is put into tiltable rotationThe tube furnace turned, being warming up to 480 DEG C melts ionic conductive agent, and by melt temperature control in the temperature, this is molten for firstBody.By lithium metal 555g, it is put into the second Iron reutilization, which is put into well formula resistance furnace, being warming up to 330 DEG C makes goldBelong to lithium fusing, stirring rod is installed, carry out strong stirring, boron powder 370g is equally divided into 5 by mixing speed 1000r/min by weightPart, interval 8min adds portion into lithium liquid, until adding, then is spaced 8min and magnesium metal grain 55g is added at one time in lithium liquid, protectsIt holds at 330 DEG C ± 10 DEG C and stirs 2h, then heat to 480 DEG C and control in the temperature, this is the second melt.
The first melt in the first crucible in rotary tube furnace is added in the second crucible in well formula resistance furnaceIn second melt of strong stirring, and it is maintained at 480 DEG C of ± 5 DEG C of stirring 2h.
Stop stirring, furnace temperature is increased to 530 DEG C with the speed of 3 DEG C/min, liquid reactions generate solid alloy ingot.It has reactedThe Li obtained under the conditions of complete by theoretical calculation7B6The 64.72wt% of modified lithium boron alloy composite negative pole material is mutually accounted for, lithium magnesium is solidSolution mutually accounts for the 33.28wt% of modified lithium boron alloy composite negative pole material, and ionic conductive agent mutually accounts for modified lithium boron alloy Compound NegativeThe 2wt% of pole material.
Embodiment 5
In oxygen content < 0.1ppm, water content 1.8ppm glove box, by the LiBr-KBr-LiF tri- as ionic conductive agentFirst salt 15g (wherein LiBr is 57.3wt%, KBr 42wt%, LiF 0.7wt%) is put into the first Iron reutilization, by the ironMatter crucible is put into the tube furnace of inclined rotating, and being warming up to 450 DEG C melts ionic conductive agent, and melt temperature is controlled in the temperatureDegree heat preservation, this is the first melt.By lithium metal 560g, it is put into the second Iron reutilization, which is put into well formula resistance furnaceInterior, being warming up to 280 DEG C melts lithium metal, installs stirring rod, carries out strong stirring, mixing speed 1000r/min, by boron powder370g is equally divided into 5 parts by weight, and interval 8min adds portion into lithium liquid, until adding, then is spaced 8min for magnesium metal grain 55gIt is added at one time in lithium liquid, is maintained at 280 DEG C ± 10 DEG C and stirs 2h, then heat to 450 DEG C and control in the temperature,This is the second melt.
The first melt in the first crucible in rotary tube furnace is added in the second crucible in well formula resistance furnaceIn second melt of strong stirring, and it is maintained at 450 DEG C of ± 5 DEG C of stirring 2h.
Stop stirring, furnace temperature is increased to 530 DEG C with the speed of 3 DEG C/min, liquid reactions generate solid alloy ingot.It has reactedThe Li obtained under the conditions of complete by theoretical calculation7B6The 64.72wt% of modified lithium boron alloy composite negative pole material is mutually accounted for, lithium magnesium is solidSolution mutually accounts for the 33.78wt% of modified lithium boron alloy composite negative pole material, and ionic conductive agent mutually accounts for modified lithium boron alloy Compound NegativeThe 1.5wt% of pole material.
Comparative example 1
In oxygen content < 0.1ppm, the glove box of water content 1.0ppm, by the LiBr-LiCl- as ionic conductive agentLiF ternary salt 60g (wherein LiBr68wt%, LiCl22wt%, LiF 10wt%) is put into the first Iron reutilization, by the ironyCrucible is put into the tube furnace of inclined rotating, and being warming up to 460 DEG C melts ionic conductive agent, and melt temperature is controlled in the temperatureHeat preservation, this is the first melt.By lithium metal 500g, it is put into the second Iron reutilization, which is put into well formula resistance furnace,Being warming up to 300 DEG C melts lithium metal, installs stirring rod, carries out strong stirring, mixing speed 1200r/min, by boron powder 400gIt is equally divided into 8 parts by weight, interval 10min adds portion into lithium liquid, until adding, then is spaced 10min for magnesium metal grain 40g mono-Secondary property is added in lithium liquid, is maintained at 300 DEG C ± 10 DEG C and stirs 4h, then heats to 460 DEG C and controls in the temperature, thisFor the second melt.
The first melt in the first crucible in rotary tube furnace is added in the second crucible in well formula resistance furnaceIn second melt of strong stirring.
Stop stirring, furnace temperature is increased to 520 DEG C with the speed of 2 DEG C/min, liquid reactions is made to generate solid alloy ingot.ReactionThe Li obtained under full terms by theoretical calculation7B6Mutually account for the 76.6% of modified lithium boron alloy composite negative pole material, the solid solution of lithium magnesiumBody mutually accounts for the 17.4wt% of modified lithium boron alloy composite negative pole material, and ionic conductive agent mutually accounts for modified lithium boron alloy composite negative pole materialThe 6wt% of material.
Alloy pig after cooling takes out from crucible in -45 DEG C of dew point of drying shed, removes Surface Oxygen using abrasive machineChange skin, 5mm band is squeezed into using Form-bar Press Machine, using double roller roll forming machine be rolled into 0.6mm strip (be pressed into every time ratio <20%), alloy surface visible black color spot is still had insoluble black particle after chloroazotic acid acidification, is illustrated to close using deionized water dissolvingThe boron powder that Jin Zhongyou does not react completely, by analysis, the reason for this is that lithium content is very few in alloy, in fusion process the second melt compared withThick to cause melt mixing effect not good enough, the boron powder that part is reunited can fully dispersed, the boron powder energy fully reacting in centre.
Comparative example 2
In oxygen content < 0.1ppm, the glove box of water content 1.1ppm, by the LiBr-LiCl- as ionic conductive agentLiF ternary salt 160g (wherein LiBr68wt%, LiCl22wt%, LiF 10wt%) is put into the first Iron reutilization, by the ironMatter crucible is put into the tube furnace of inclined rotating, and being warming up to 460 DEG C melts ionic conductive agent, and melt temperature is controlled in the temperatureDegree heat preservation, this is the first melt.By lithium metal 563.2g, it is put into the second Iron reutilization, which is put into well formula resistanceIn furnace, being warming up to 300 DEG C melts lithium metal, installs stirring rod, carries out strong stirring, mixing speed 1200r/min, by boron powder256.8g is equally divided into 6 parts by weight, and interval 10min adds portion into lithium liquid, until adding, then is spaced 10min for magnesium metalGrain 20g is added at one time in lithium liquid, is maintained at 300 DEG C ± 10 DEG C and is stirred 4h, is then heated to 460 DEG C and is controlled in the temperatureHeat preservation, this is the second melt.
The first melt in the first crucible in rotary tube furnace is added in the second crucible in well formula resistance furnaceIn second melt of strong stirring.
Stop stirring, furnace temperature is increased to 520 DEG C with the speed of 2 DEG C/min, liquid reactions generate solid alloy ingot.It has reactedThe Li obtained under the conditions of complete by theoretical calculation7B6Mutually account for the 44.92% of modified lithium boron alloy composite negative pole material, the solid solution of lithium magnesiumBody mutually accounts for the 39.08wt% of modified lithium boron alloy composite negative pole material, and ionic conductive agent mutually accounts for modified lithium boron alloy composite negative poleThe 16wt% of material.
Alloy pig after cooling takes out from crucible in -45 DEG C of dew point of drying shed, removes Surface Oxygen using abrasive machineChange skin, 5mm band is squeezed into using Form-bar Press Machine, using double roller roll forming machine be rolled into 0.6mm strip (be pressed into every time ratio <20%) phenomena such as, alloy strip cracks, layering can not assemble battery use, by analysis, the reason for this is that ionic conductive agentAddition is excessive, causes alloy ductility insufficient.
Comparative example 3
In oxygen content < 0.1ppm, the glove box of water content 1.0ppm, by the LiBr-LiCl- as ionic conductive agentLiF ternary salt 60g (wherein LiBr68wt%, LiCl22wt%, LiF 10wt%) is put into the first Iron reutilization, by the ironyCrucible is put into the tube furnace of inclined rotating, and being warming up to 460 DEG C melts ionic conductive agent, and melt temperature is controlled in the temperatureHeat preservation, this is the first melt.By lithium metal 700g, it is put into the second Iron reutilization, which is put into well formula resistance furnace,Being warming up to 380 DEG C melts lithium metal, installs stirring rod, carries out strong stirring, mixing speed 1000r/min, by boron powder 220gIt is equally divided into 4 parts by weight, interval 10min adds portion into lithium liquid, until adding, then is spaced 10min for magnesium metal grain 20g mono-Secondary property is added in lithium liquid, is maintained at 380 DEG C ± 10 DEG C and stirs 1.5h, then heats to 460 DEG C and controls in the temperature,This is the second melt.
The first melt in the first crucible in rotary tube furnace is added in the second crucible in well formula resistance furnaceIn second melt of strong stirring.
Stop stirring, furnace temperature is increased to 520 DEG C with the speed of 5 DEG C/min, liquid reactions generate solid alloy ingot.Pass through reasonBy the Li being calculated7B6The 38.48wt% of modified lithium boron alloy composite negative pole material is mutually accounted for, lithium magnesium sosoloid mutually accounts for modified lithiumThe 55.52wt% of boron alloy composite negative pole material, ionic conductive agent mutually account for the 6wt% of modified lithium boron alloy composite negative pole material.
Alloy pig after cooling takes out from crucible in -43 DEG C of dew point of drying shed, removes Surface Oxygen using abrasive machineChange skin, 5mm band is squeezed into using Form-bar Press Machine, using double roller roll forming machine be rolled into 0.6mm strip (be pressed into every time ratio <20%), then stamped machine is washed into the disk of diameter 58mm.
Using this lithium boron alloy piece as cathode, cobalt disulfide be anode (anode is excessive), LiBr-LiCl-LiF+MgO is electrolysisMatter is assembled into thermal cell, stands 6 hours in -40 DEG C of cryogenic boxes, then takes out and carries out 13A constant-current discharge, test result such as Fig. 5Shown, as can be seen from Figure 5, the modification lithium boron alloy piece obtained using the present embodiment is had under the moment of many places voltage in early period of dischargingDrop illustrates that short circuit locally occurs in battery, and through battery dissection and analysis, there is cathode overflow in battery side, and the short-circuit reason of analysis isLithium boron alloy lithium content is excessively high, and lithium magnesium sosoloid cannot be adsorbed in wherein by the less lithium boron alloy skeleton of relative amount completely,Occur caused by overflowing under the discharge environment of high temperature and pressure.
Above-described is only embodiments of the present invention, it should be noted here that for those of ordinary skill in the artFor, without departing from the concept of the premise of the invention, improvement can also be made, but these belong to protection model of the inventionIt encloses.