CN103824999A - Lithium battery cathode and preparation method thereof as well as lithium battery - Google Patents
Lithium battery cathode and preparation method thereof as well as lithium battery Download PDFInfo
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Abstract
The invention provides a lithium battery cathode and a preparation method thereof. The lithium battery cathode comprises a current collector and a cathode active material located on the surface of the current collector, wherein the anode active material adopts a two-layered composite structure; the first layer near to the current collector side is composed of a carbon material and a first material; the second layer far away from the current collector side is composed of the first material and a second material; the first material is one or more of a silicon monomer and a silicon-containing compound; the second material is an NASICON (Natrium Super Ionic Conductor) solid electrolyte; the contents of the carbon material and the first material in the first layer are distributed in grade in the thickness direction of the lithium battery cathode, the content of the carbon material nearer to the current collector is higher, and the content of the first material nearer to the current collector is lower. The invention further provides a lithium battery adopting the cathode. The lithium battery adopting the cathode, provided by the invention, has excellent circulating performance when achieving higher specific capacity.
Description
Technical field
The invention belongs to technical field of lithium batteries, be specifically related to a kind of cathode of lithium battery and preparation method thereof and adopt the lithium battery of this cathode of lithium battery.
Background technology
At present, generally in lithium ion battery negative be made into slurry after adopting individual layer active material layer to mix with binding agent, conductive agent, solvent etc., then adopt the technology of slit film to be coated on Copper Foil collector and form negative electrode.The active material that commercial Li-ion battery negative pole adopts is graphite-like material with carbon element, but its theoretical specific capacity only has 372mAh/g, has limited the further raising of lithium ion battery specific energy.Silicon materials receive much concern as high power capacity Novel anode material.But there is serious volumetric expansion and contraction in silicon materials in removal lithium embedded process, cannot image-stone China ink equally to be stablized, fine and close SEI film, this has limited the application of silicon materials as dynamic stabilization negative pole greatly.
No matter be graphite-like material with carbon element or silicon materials, the main component of its surface passivation SEI film is except the organic component that part is difficult to differentiate, major part is lithium carbonate and lithium fluoride inorganic component, and the two is not good lithium ion conductor, will certainly lithium ion be produced and be hindered in the migration of negative terminal surface, and the formation of the two be that to reduce the coulomb efficiency of battery be cost.Particularly silicon materials volume in cyclic process constantly expands, shrinks the accumulation that has caused the inert component such as lithium carbonate, lithium fluoride, and this has not only consumed active lithium reversible in lithium battery, has also hindered lithium ion at negative pole migrating channels.Along with the carrying out of circulation, material granule is constantly split into less particle, the solid electrolyte film of particle surface is destroyed and formation again constantly, the solid electrolyte film that final granule surface constantly thickens has been blocked the electronic conductance between material, material and electrode lose and electrically contact, become " dead capacity ", cause capacity attenuation in cyclic process.
In addition, in lithium battery, SEI film is inhomogeneous on negative pole thickness direction, and in existing cathode of lithium battery, do not focus on electrical conductivity passage and the ionic transport passages demand status in zones of different, so, the problem of easily bringing cycle performance to decline in the time that electrode is thicker or adopt the more serious silicium cathode of side reaction.
Summary of the invention
The invention solves negative pole that in prior art, lithium battery adopts causes battery to have the low and poor technical problem of cycle performance of specific capacity.
The invention provides a kind of cathode of lithium battery, described cathode of lithium battery comprises collector and is positioned at the negative active core-shell material of collection liquid surface; Described negative active core-shell material is two layer composite structure, is wherein made up of material with carbon element and the first material near the ground floor on afflux side, is made up of the first material and the second material away from the second layer on afflux side; Described the first material is selected from least one in elementary silicon, silicon-containing compound, and described the second material is NASICON type solid electrolyte;
The content of material with carbon element and the first material distribution gradient on described cathode of lithium battery thickness direction in described ground floor, and from collector, the content of the position material with carbon element close to more content higher, position the first material from collector close to more is lower.
The present invention also provides the preparation method of described cathode of lithium battery, comprises the following steps:
S10, be mixed with ground floor slurry after material with carbon element is mixed with the first material, at collection liquid surface by casting machine by ground floor slurry curtain coating in collection liquid surface, form ground floor at collection liquid surface after dry;
S20, be mixed with second layer slurry after the first material is mixed with the second material, by slit film mode, second layer slurry be coated on to ground floor surface on ground floor surface, form the second layer on ground floor surface after dry, obtain described cathode of lithium battery.
Finally, the invention provides a kind of lithium battery, comprise positive pole, negative pole and be arranged at the barrier film between positive pole, negative pole, described negative pole cathode of lithium battery provided by the invention.
Cathode of lithium battery provided by the invention, take into full account the concrete condition of SEI film uneven distribution on negative pole thickness direction in electrode production process, SEI film near afflux side is thinner, and it is thicker away from the SEI film of afflux side (near barrier film side), therefore adopting the first material of height ratio capacity and the material with carbon element of high stability near afflux side, and its content gradient on negative pole thickness direction distributes, thereby can effectively increase the electron flux near afflux side in described cathode of lithium battery, alleviate poor the brought cycle performance decline problem of electrical conductivity; And adopting the first material of height ratio capacity and the second material of high ionic conductivity away from afflux side (near barrier film side), make cathode of lithium battery provided by the invention in obtaining compared with height ratio capacity, can also effectively avoid the problem of the ionic conduction blocking-up that the lasting side reaction of the first material causes, thereby further guarantee to adopt the lithium battery of negative pole provided by the invention to there is good cycle performance.
Embodiment
The invention provides a kind of cathode of lithium battery, described cathode of lithium battery comprises collector and is positioned at the negative active core-shell material of collection liquid surface; Described negative active core-shell material is two layer composite structure, is wherein made up of material with carbon element and the first material near the ground floor on afflux side, is made up of the first material and the second material away from the second layer on afflux side; Described the first material is selected from least one in elementary silicon, silicon-containing compound, and described the second material is NASICON type solid electrolyte;
The content of material with carbon element and the first material distribution gradient on described cathode of lithium battery thickness direction in described ground floor, and from collector, the content of the position material with carbon element close to more content higher, position the first material from collector close to more is lower.
The present inventor finds, in lithium battery, near negative electrode embedding lithium and the lithium-inserting amount maximum at first of barrier film side, current potential minimum and with the contact area maximum of electrolyte, so the SEI forming is thicker; In thickness of electrode direction its SEI film thickness difference of the diverse location of negative pole, be also different to the demand of lithium ion conductivity and electronic conductivity, wherein need to be compared with large lithium ion conductivity near barrier film side and lower to the requirement of electronic conductivity, and near afflux side to having relatively high expectations of electronic conductivity and lower to the requirement of lithium ion conductivity.
The present invention analyzes various negative materials used in the prior art, finds: 1, existing lithium battery, in electrode production process, all do not consider the inhomogeneities of SEI film on negative pole thickness direction; 2, in the time adopting graphite-like material with carbon element to make negative pole, negative pole thickness hour can not affect the cycle performance of battery, but the problem because of lithium concentration gradient cannot be given full play to its removal lithium embedded performance by the active material near afflux side when negative pole enlarged in thickness; 3, in the time that the larger material such as silicon, tin of employing change in volume is made negative pole, along with the lasting increase that causes SEI film thickness is shunk in the volumetric expansion of carrying out active material of circulation, have a strong impact on the cycle performance of battery; 4, the SEI film lithium ion conductivity of natural formation is very low, and wherein the inorganic component of several molecule bed thickness just likely causes negative electrode active material to lose efficacy.
For above analysis, the present inventor, by further experiment discovery, in the present invention, can pass through to improve the distribution situation of active material in cathode of lithium battery, the on the one hand varied in thickness of SEI film in matched electrodes, keeps the cycle performance of the first material on the other hand.Particularly, in the present invention, described negative active core-shell material is two layer composite structure, is wherein made up of material with carbon element and the first material near the ground floor on afflux side, is made up of the first material and the second material away from the second layer on afflux side; The content of material with carbon element and the first material distribution gradient on described cathode of lithium battery thickness direction in described ground floor, and from collector, the content of the position material with carbon element close to more content higher, position the first material from collector close to more is lower.
In the present invention, formed by material with carbon element and the first material near the ground floor on afflux side.Wherein, material with carbon element for lithium secondary battery anode provides stable removal lithium embedded capacity, on the other hand for negative electrode provides good electron channel, can keep the quick conduction of electronics on the one hand in charging and discharging lithium battery process, reduces ohmic polarization.The first material is selected from elementary silicon, at least one in silicon-containing compound, it can provide higher specific capacity, but the accessory substance brightness that it produces in charge and discharge cycles process hinders the electron channel of negative pole on negative pole thickness direction, and in negative pole electron flux distribution gradient on negative pole thickness direction, electron flux near afflux side will be far above the electron flux away from afflux side (near barrier film side), so distribution gradient on thickness direction by the first material and material with carbon element, particularly, the content of the position material with carbon element from collector close to is more higher, the content of position the first material from collector close to is more lower, thereby can effectively increase the electron flux near afflux side in described cathode of lithium battery, alleviate poor the brought cycle performance decline problem of electrical conductivity.
On the other hand, be subject to the double influence of electrolyte infiltration and lithium concentration gradient, lithium ion flux is also inhomogeneous on negative pole thickness direction, particularly negative pole is the region of lithium ion flux maximum away from the outer surface (being second layer surface) of afflux side (near barrier film side), also be the most serious region of side reaction, can effectively alleviate so improve negative pole outer surface the circulatory problems that ionic conduction is brought.
In existing electrolyte system take carbonates solvent and hexafluorophosphoric acid lithium salts as main, in the SEI film forming in the time of negative pole embedding lithium, inorganic component is mainly take the lower lithium carbonate of ionic conductivity, lithium fluoride and lithia as main, and most film for additive also cannot change the inorganic component in SEI.Therefore, in cathode of lithium battery provided by the invention, be made up of the first material and the second material away from the second layer on afflux side, described the second material is the NASICON type solid electrolyte that lithium ion conductivity is better than natural SEI inorganic component.Under described NASICON type solid electrolyte room temperature, ionic conductivity can reach 10
-4s/cm; Such material can form the lithium phosphate matrix that ionic conductivity is better than lithium carbonate and lithium fluoride in embedding lithium process, such ion conductor is conducive to improve the stability of electrolyte interface film, improve the ionic conductivity of inorganic component in interfacial film, the negative issue that the side reaction product of having avoided the first material volume to expand bringing is accumulated.Simultaneously, in the present invention, in the second layer, also contain the first material of height ratio capacity, make cathode of lithium battery provided by the invention on the basis that does not affect electrical conductivity, also there is higher specific capacity near the outer surface of barrier film side, can also effectively avoid SEI film thickness in circulating battery process to increase the ionic conduction Problem of Failure of bringing, further guarantee that the lithium battery of negative pole provided by the invention has good cycle performance.
As previously mentioned, the content of material with carbon element and the first material distribution gradient on described cathode of lithium battery thickness direction in described ground floor, and from collector, the content of the position material with carbon element close to more content higher, position the first material from collector close to more is lower.Under preferable case, in described ground floor, the content of the first material is by being increased to gradually the 20-60wt% near second layer side near the 0.1-2wt% on afflux side.Correspondingly, in described ground floor, the content of material with carbon element is by being reduced to gradually the 40-80wt% near second layer side near the 99.9wt% on afflux side.
In the present invention, the described second layer is for guaranteeing the high ionic conductivity of negative pole outer surface, there is no specific (special) requirements for the content distribution of the first material and the second material wherein.Under preferable case, facilitate the moulding of the second layer, in the described second layer, the content of the first material and the second material is uniformly distributed on described cathode of lithium battery thickness direction.More preferably in situation, in the described second layer, the content of the second material is 5-50wt%.
In the present invention, the thickness of described ground floor is 80-150 micron, and the thickness of the second layer is 0.1-50 micron.
As scheduled, described the first material is selected from least one in elementary silicon, silicon-containing compound.Wherein, described silicon-containing compound can be selected from one or more in silicon monoxide, silicon alloy or silico-carbo-oxygen pottery, and the present invention is not particularly limited.
Described the second material is NASICON type solid electrolyte.As those skilled in the art's common practise, the NASICON meaning is Na+Super+ionic+Conductor, and Na wherein can be replaced by Li, and typical NASICON structure is by MO
6octahedron and XO
4tetrahedron concurrent connects and forms [M
2(XO
4)
3] rigid structure and then mirror image arrange and form open three-dimensional structure, sodium or lithium ion move in three-dimensional structure.NASICON type lithium solid electrolyte has higher ionic conductivity.Under preferable case, described the second material is selected from LiTi
2(PO
4)
3, LiZr
2(PO
4)
3, LiGe
2(PO
4)
3, LiSn
2(PO
4)
3, LiPb
2(PO
4)
3, Li
3ti
2(PO
4)
3and one or more in the doping vario-property compound of aforementioned various materials, but be not limited to this.
In the present invention, described material with carbon element is the material with carbon element that can reversibly embed and deviate from lithium ion known in the field, for example, can be selected from one or more in native graphite, Delanium, soft carbon, carbon black, thermal cracking carbon, carbon fiber, but be not limited to this.Under preferable case, described material with carbon element is selected from for example, for example, for example, in thermal cracking carbon (hard carbon), soft carbon (coke), Delanium (graphitized intermediate-phase carbon microballon), carbon fiber one or more.
The present invention also provides the preparation method of described cathode of lithium battery, comprises the following steps:
S10, be mixed with ground floor slurry after material with carbon element is mixed with the first material, at collection liquid surface by casting machine by ground floor slurry curtain coating in collection liquid surface, form ground floor at collection liquid surface after dry;
S20, be mixed with second layer slurry after the first material is mixed with the second material, by slit film mode, second layer slurry be coated on to ground floor surface on ground floor surface, form the second layer on ground floor surface after dry, obtain described cathode of lithium battery.
According to method provided by the invention, because the proportion of material with carbon element is great compared with the ratio of the first material, therefore in ground floor slurry curtain coating process, the sinking speed of material with carbon element can obviously be greater than the sinking speed of the first material, after curtain coating is completed, content content higher, the first material near the material with carbon element on afflux side is lower, and higher away from the material with carbon element content on afflux side content lower, the first material, thus obtain described on negative pole thickness direction the ground floor structure of distribution gradient.
Under preferable case, the condition of described curtain coating also comprises: curtain coating speed is 0.1-0.8m/min, and casting machine vibration frequency is 5-500Hz.
The forming method of the described second layer is slit coating method, and the method is conventionally known to one of skill in the art, in the present invention, repeats no more.
As those skilled in the art's common practise, in the time of preparation ground floor slurry, second layer slurry, also need to add binding agent and solvent, the binding agent adopting and solvent are that those skilled in the art prepare various binding agents and the solvent that electrode has often, and the present invention is not particularly limited.For example, described binding agent can adopt sodium carboxymethylcellulose (CMC), styrene-butadiene latex (SBR), and solvent can adopt water, but is not limited to this.
Finally, the invention provides a kind of lithium battery, comprise positive pole, negative pole and be arranged at the barrier film between positive pole, negative pole, described negative pole cathode of lithium battery provided by the invention.Lithium battery provided by the invention has higher specific capacity and good cycle performance.
In order to make technical problem solved by the invention, technical scheme and beneficial effect clearer, below in conjunction with embodiment, the present invention is further elaborated.Should be appreciated that specific embodiment described herein, only in order to explain the present invention, is not intended to limit the present invention.
Embodiment 1
(1) take water as solvent, CMC and SBR be binding agent, according to quality than Delanium: the ratio preparation ground floor slurry of elementary silicon: CMC:SBR=90:10:3:2;
(2) the ground floor slurry of 100g is placed in to the casting machine that substrate is Copper Foil, controls 120 ℃ of temperature, vibration frequency 50Hz, curtain coating speed and be after 0.2m/min, drying time 5min, forming thickness at Copper Foil collection liquid surface is the ground floor of 100 microns;
(3) take water as solvent, CMC and SBR be binding agent, according to quality than elementary silicon: phosphoric acid tin lithium LiSn
2(PO
4)
3: the ratio preparation second layer slurry of CMC:SBR=65:30:3:2;
(4) second layer slurry is placed in to slit device for coating, at ground floor surface-coated second layer slurry, dry rear formation thickness is the dry film of 10 microns, obtains the cathode of lithium battery S1 of the present embodiment; The thickness of its ground floor is 100 microns, elementary silicon in ground floor along distribution gradient on negative pole thickness direction, silicone content is by increasing to gradually the 30wt% near second layer side near the 0.1wt% on Copper Foil afflux side, and the content of graphite is reduced to the 65.24wt% near second layer side gradually by the 95.14wt% on nearly Copper Foil afflux side; The thickness of (content of binding agent is 4.76%) second layer is 10 microns, elementary silicon and LiSn
2(PO
4)
3in the second layer, along being uniformly distributed on negative pole thickness direction, and in the second layer, the content of phosphoric acid tin lithium is 30wt%.
(5), take above-mentioned cathode of lithium battery S1 as work electrode, lithium metal is to electrode, is assembled into button cell A1 in argon gas glove box.
(6) using above-mentioned cathode of lithium battery S1 as negative plate, adopting cobalt acid lithium is that positive electrode active materials adds respectively binding agent, conductive agent and solvent, makes positive through batching, coating, dry, roll-in, after cutting.The polypropylene diaphragm of positive and negative plate and 20 micron thickness is wound into the battery core of rectangular lithium ion battery, and this battery core is packed in the rectangular cell aluminum hull of 5mm × 34mm × 50mm and seal, make 053450 type lithium ion battery, then through fluid injection, ageing, change into, after partial volume, obtain the full battery B1 of the present embodiment.
Embodiment 2
Adopt the step identical with embodiment 1 to prepare cathode of lithium battery S2, button cell A2 and the full battery B2 of the present embodiment, difference is:
In step (3), adopt titanium phosphate lithium LiTi
2(PO
4)
3replace the LiSn in embodiment 1
2(PO
4)
3.
Embodiment 3
Adopt the step identical with embodiment 1 to prepare cathode of lithium battery S3, button cell A3 and the full battery B3 of the present embodiment, difference is:
In step (1), adopt silicon monoxide to replace the elementary silicon in embodiment 1, and quality is than Delanium: silicon monoxide: CMC:SBR=85:15:3:2;
In step (3), adopt silicon monoxide to replace the elementary silicon in embodiment 1, and quality is than silicon monoxide: LiSn
2(PO
4)
3: CMC:SBR=60:35:3:2;
In step (4), in the cathode of lithium battery S3 obtaining, the thickness of its ground floor is 80 microns, silicon monoxide in ground floor along distribution gradient on negative pole thickness direction, silicon monoxide content is by increasing to gradually the 35wt% near second layer side near the 0.3wt% on Copper Foil afflux side, and the content of graphite is reduced to the 60.24wt% near second layer side gradually by the 94.94wt% on nearly Copper Foil afflux side; The thickness of the second layer is 20 microns, silicon monoxide and LiSn
2(PO
4)
3in the second layer, along being uniformly distributed on negative pole thickness direction, and in the second layer, the content of phosphoric acid tin lithium is 35wt%.
Comparative example 1
(1) take water as solvent, CMC and SBR be binding agent, according to quality than graphite: the ratio preparation slurry of elementary silicon: CMC:SBR=90:10:3:2;
(2) slurry of 100g step (1) preparation is placed in to slit device for coating, applies slurry at copper foil surface, dry rear formation thickness is the dry grinding of 110 microns, obtains the cathode of lithium battery SC1 of this comparative example.
(3), take above-mentioned cathode of lithium battery SC1 as work electrode, lithium metal is to electrode, is assembled into button cell AC1 in argon gas glove box.
(4) using above-mentioned cathode of lithium battery S1 as negative plate, adopting cobalt acid lithium is that positive electrode active materials adds respectively binding agent, conductive agent and solvent, makes positive through batching, coating, dry, roll-in, after cutting.The polypropylene diaphragm of positive and negative plate and 20 micron thickness is wound into the battery core of rectangular lithium ion battery, and this battery core is packed in the rectangular cell aluminum hull of 5mm × 34mm × 50mm and seal, make 053450 type lithium ion battery, then through fluid injection, ageing, change into, after partial volume, obtain the full battery BC1 of the present embodiment.
Performance test
(1) specific capacity test
Get each 20 of button cell A1-A3 and AC1, on the strange BK-6016 secondary cell of indigo plant device for detecting performance, test each battery capacity at 25 ± 1 ℃.Testing procedure is as follows: shelve 30min; 0.2mA constant-current discharge is to 0.005V; 0.1mA constant-current discharge is to 0.005V; 0.05mA constant-current discharge is to 0.005V; Shelve 10 minutes; 0.2mA constant current charge is to 2.5V.Record active material quality in specific capacity=test battery capacity/button cell of active material in each battery, average.Test result is as shown in table 1.Note: embedding lithium specific capacity is total specific capacity of adding up in discharge step, de-lithium capacity is total specific capacity of adding up in charge step.
(2) loop test
Get each 20 of full battery B1-B3 and BC1, holding up on day BS-9300 secondary cell device for detecting performance, under 25 ± 1 ℃ of conditions, battery is carried out to charge and discharge cycles test with 0.2C.Step is as follows: shelve 10min; Constant voltage charge ends to 4.2V/0.05C; Shelve 10min; Constant-current discharge, to 3.0V, is 1 circulation.Repeat this step, in cyclic process when battery capacity lower than discharge capacity first 80% time, loop termination, this cycle-index is the cycle life of battery, averages for every group.Test result is as shown in table 2.
Table 1
| Battery numbering | A1 | A2 | A3 | AC1 |
| Embedding lithium specific capacity/mAh/g | 731 | 683 | 822 | 650 |
| De-lithium specific capacity/mAh/g | 599 | 594 | 616 | 507 |
| Efficiency/% first | 82 | 87 | 75 | 78 |
Table 2
| Battery numbering | B1 | B2 | B3 | BC1 |
| Cycle life/time | 418 | 426 | 492 | 25 |
| The internal resistance of cell/m Ω after circulation | 63 | 71 | 79 | 106 |
Can find out from the test result of upper table 1, the battery sample that adopts negative pole provided by the invention to make, its specific capacity and cycle performance are all obviously better than the battery sample in comparative example.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any modifications of doing within the spirit and principles in the present invention, be equal to and replace and improvement etc., within all should being included in protection scope of the present invention.
Claims (10)
1. a cathode of lithium battery, described cathode of lithium battery comprises collector and is positioned at the negative active core-shell material of collection liquid surface; It is characterized in that, described negative active core-shell material is two layer composite structure, is wherein made up of material with carbon element and the first material near the ground floor on afflux side, is made up of the first material and the second material away from the second layer on afflux side; Described the first material is selected from least one in elementary silicon, silicon-containing compound, and described the second material is NASICON type solid electrolyte;
The content of material with carbon element and the first material distribution gradient on described cathode of lithium battery thickness direction in described ground floor, and from collector, the content of the position material with carbon element close to more content higher, position the first material from collector close to more is lower.
2. cathode of lithium battery according to claim 1, is characterized in that, in described ground floor, the content of the first material is by being increased to gradually the 20-60wt% near second layer side near the 0.1-2wt% on afflux side.
3. cathode of lithium battery according to claim 1, is characterized in that, in the described second layer, the content of the first material and the second material is uniformly distributed on described cathode of lithium battery thickness direction, and the content of the second material is 5-50wt%.
4. according to the cathode of lithium battery described in claim 1-3 any one, it is characterized in that, the thickness of described ground floor is 80-150 micron, and the thickness of the second layer is 0.1-50 micron.
5. according to the cathode of lithium battery described in claim 1-3 any one, it is characterized in that, described the first material is selected from least one in elementary silicon, silicon monoxide, silicon alloy or silico-carbo-oxygen pottery.
6. according to the cathode of lithium battery described in claim 1-3 any one, it is characterized in that, described the second material is selected from LiTi
2(PO
4)
3, LiZr
2(PO
4)
3, LiGe
2(PO
4)
3, LiSn
2(PO
4)
3, LiPb
2(PO
4)
3, Li
3ti
2(PO
4)
3and one or more in doping vario-property compound.
7. according to the cathode of lithium battery described in claim 1-3 any one, it is characterized in that, described material with carbon element is selected from one or more in native graphite, Delanium, soft carbon, carbon black, RESEARCH OF PYROCARBON, carbon fiber.
8. the preparation method of cathode of lithium battery claimed in claim 1, is characterized in that, comprises the following steps:
S10, be mixed with ground floor slurry after material with carbon element is mixed with the first material, at collection liquid surface by casting machine by ground floor slurry curtain coating in collection liquid surface, form ground floor at collection liquid surface after dry;
S20, be mixed with second layer slurry after the first material is mixed with the second material, by slit film mode, second layer slurry be coated on to ground floor surface on ground floor surface, form the second layer on ground floor surface after dry, obtain described cathode of lithium battery.
9. preparation method according to claim 8, is characterized in that, in step S10, the condition of described curtain coating comprises: curtain coating speed is 0.1-0.8m/min, and casting machine vibration frequency is 5-500Hz.
10. a lithium battery, comprises positive pole, negative pole and is arranged at the barrier film between positive pole, negative pole, it is characterized in that, described negative pole is the cathode of lithium battery described in claim 1-7 any one.
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