Patent Grant
12237504
The present application is a National Stage application of PCT international application: PCT/CN2019/125945, filed on Dec. 17, 2019, which claims the priority of Chinese patent application 201811541619.8, filed on Dec. 17, 2018, the disclosure of which is hereby incorporated by reference in its entirety.
The present application relates to the field of energy storage, particularly to an anode material and an electrochemical device and an electronic device using the same, and more particularly to a lithium ion battery.
Electrochemical devices (for example, lithium ion batteries) have entered the daily lives of people with the advances in technology and environmental protection. In recent years, silicon has been considered to be the anode material of a lithium ion battery that is most likely to be applied on a large scale because the reversible capacity of silicon is up to 4,200 mAh/g. However, the volume expansion of silicon is about 400% during charging and discharging. Ultra-high volume expansion will cause the destruction of the solid electrolyte interface (SEI) membrane, and the fresh surface of the material is continuously exposed, thereby continuously consuming the electrolytic solution, and leading to repeated formation of the SEI. Although silicon-oxygen material has a certain decrease in capacity compared with pure silicon, silicon-oxygen material can significantly reduce volume expansion to some extent. Volume expansion can be controlled to be only 120-160% by reasonably designing the silicon-oxygen ratio and particle size thus optimizing the cell preparation process. However, the current requirement for the high cycle life of lithium ion batteries cannot yet be achieved.
In view of this, in order to meet the requirement for high cycle life, it is necessary to further refine and improve the structure of the anode material.
The embodiments of the present application provide an anode material and a method for preparing the same in an attempt to solve at least one of the problems in the related art to at least some extent. The embodiments of the present application also provide an anode, an electrochemical device and an electronic device using the anode material.
In one embodiment, the present application provides an anode material, including:
In another embodiment, the present application provides a method for preparing an anode material, wherein the method includes:
In another embodiment, the present application provides an anode, including the anode material according to the present application.
In another embodiment, the present application provides an electrochemical device, including the anode according to the present application.
In another embodiment, the present application provides an electronic device, including the electrochemical device according to the present application.
Since the material would expand and shrink during charging and discharging, a tight coating structure can effectively alleviate structural damage during the process. On the other hand, the destruction of the material will generate a fresh interface, and a large amount of SEI by-products will be produced after multiple cycles. When the interface is not tightly or firmly bonded, such thick layer of by-products will promote and accelerate the peeling of the carbon layer, thereby accelerating the attenuation and failure of the material.
The main methods for improving the cycle performance of the silicon-oxygen material include the following: coating a silicon-oxygen material with carbon, disposing an intermediate gap layer in the middle of the carbon-coated silicon-oxygen material, reducing the size of a silicon-oxygen material, coating a silicon-oxygen material with a polymer, and the like. In these coating methods, the carbon-coated material has better electronic conductivity and higher stability. However, the carbon-coated silicon-oxygen material is likely to be decarburized due to repeated shearing forces during the processing of the battery electrode, and therefore the coulombic efficiency is affected. The SEI membrane formation consumes the electrolytic solution. On the other hand, the expansion and contraction and cracking of the silicon during multiple cycles causes the carbon layer to be easily peeled off the substrate, and be wrapped by the by-products with the SEI being formed, thereby greatly increasing the electrochemical impedance and polarization, and affecting the cycle life. Therefore, the improvement of the interfacial bonding performance between the carbon layer and the silicon-oxygen material is very important for improving the cycle life and improving the stability of the cycle structure.
In the anode material provided according to the present application, the oxide MeOy layer has an amorphous structure and contains pore structures therein. On the one hand, these pore structures can increase the transmission of lithium ions in the material and reduce the internal resistance of polarization. On the other hand, the surface of the oxide MeOy layer adjacent to the carbon layer also has open pore structures, and the carbon precursor can penetrate into these open pore structures, so that the sintered carbon layer is more tightly bonded to the oxide MeOy layer. An interlocking effect is generated, thereby effectively improving the interfacial bonding force between the carbon layer and the substrate. Further, the oxide MeOy layer and the silicon-oxygen material substrate can form a good connection by the chemical bonds “Me-O—Si”. Therefore, such structural design can significantly improve the structural stability of the material during the cycle, so that the cycle life is significantly improved.
Additional aspects and advantages of the embodiments of the present application will be described and shown in part in the following explanation or set forth by implementation of the embodiments of the present application.
The drawings, which are necessary to describe the examples of the present application or the prior art, will be briefly described below to facilitate the description of the examples of the present application. It is obvious that the drawings in the following description are only part of the examples of the present application. Those skilled in the art could obtain the drawings of other examples according to the structures illustrated in these drawings without the need to pay creative work.
Comparative Example 4 according to the present application;
Examples of the present application will be described in detail below. The examples of the present application should not be construed as limiting the present application.
As used herein, the term “about” is used to describe and explain a small variation. When used in connection with an event or circumstance, the term may refer to an example in which the event or circumstance occurs precisely and an example in which the event or circumstance occurs approximately. For example, when used in connection with a value, the term may refer to a range of variation less than or equal to ±10% of the value, for example, less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, less than or equal to ±0.05%, etc. In addition, quantities, ratios, and other values are sometimes presented in a range format in the present application. It should be understood that the range format is intended for convenience and briefness and should be understood flexibly. Not only are the values explicitly limited in the range contained, but also all individual values or sub-ranges covered within the range are contained as each value and each sub-range are explicitly specified.
I. Anode Material
The examples of the present application provide an anode material, the anode material including:
In some examples, the MeOy layer has a non-open pore structure.
In some examples, the silicon compound SiOx contains SiO, SiO2, or a combination thereof.
In some examples, the MeOy layer contains TiO2, Al2O3, or a combination thereof.
In some examples, the MeOy layer contains carbon, wherein, based on the total weight of the silicon compound SiOx and the MeOy layer, the content of the carbon in the MeOy layer is about 0.1 wt % to 1 wt %.
In some examples, the MeOy layer contains carbon, wherein, based on the total weight of the silicon compound SiOx and the MeOy layer, the content of the carbon in the MeOy layer is about 0.2 wt % to 0.8 wt %.
In some examples, the MeOy layer contains carbon, wherein, based on the total weight of the silicon compound SiOx and the MeOy layer, the content of the carbon in the MeOy layer is about 0.2 wt % to 0.6 wt %.
In some examples, the MeOy layer contains carbon, wherein, based on the total weight of the silicon compound SiOx and the MeOy layer, the content of the carbon in the MeOy layer is about 0.2 wt % to 0.4 wt %.
In some examples, the average particle diameter of the silicon compound SiOx is about 500 nm to 30 μm. In some embodiments, the average particle diameter of the silicon compound SiOx is about 1 μm to 30 μm. In some examples, the average particle diameter of the silicon compound SiOx is about 3 μm to 8 μm.
In some examples, the thickness of the MeOy layer is about 2 nm to 1000 nm. In some examples, the thickness of the MeOy layer is about 10 nm to 500 nm. In some examples, the thickness of the MeOy layer is about 10 nm to 50 nm. In some examples, the thickness of the MeOy layer is about 5 nm to 50 nm.
In some examples, the thickness of the carbon layer is about 2 nm to 1000 nm. In some examples, the thickness of the carbon layer is about 10 nm to 100 nm. In some examples, the thickness of the carbon layer is about 10 nm to 50 nm.
In some examples, the content of the carbon contained in the anode material is about 1 wt % to 10 wt % based on the total weight of the anode material.
In some examples, the content of the carbon contained in the anode material is about 1 wt % to 8 wt % based on the total weight of the anode material.
In some examples, the content of the carbon contained in the anode material is about 1 wt % to 6 wt % based on the total weight of the anode material.
In some examples, the content of the carbon contained in the anode material is about 2 wt % to 5 wt % based on the total weight of the anode material.
In some examples, the specific surface area of the anode material is about 2 cm2/g to 20 cm2/g. In some examples, the specific surface area of the anode material is about 5 cm2/g to 20 cm2/g. In some examples, the specific surface area of the anode material is about 5 cm2/g to 10 cm2/g.
II. Method for Preparing Anode Material
The examples of the present application provide a method for preparing any above anode material, including:
According to some examples of the present application, the pore-forming agent includes at least one of the following compounds: polyvinylpyrrolidone, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, hexadecyl trimethyl ammonium bromide, and octadecyl trimethylammonium bromide.
According to some examples of the present application, the carbon precursor is a mixture of phenolic resin and hexamethylenetetramine, wherein the weight ratio of the phenolic resin to the hexamethylenetetramine is about 12:1 to 6:1. According to some examples of the present application, the weight ratio of the phenolic resin to hexamethylenetetramine is about 10:1 to 8:1. According to some examples of the present application, the weight ratio of the phenolic resin to hexamethylenetetramine is about 9:1.
According to some examples of the present application, the oxide precursor MeXn contains isopropyl titanate, aluminum isopropoxide or a combination thereof.
According to some examples of the present application, the organic solvent includes at least one of the following solvents: ethanol, methanol, n-hexane, N,N-dimethylformamide, pyrrolidone, acetone, toluene, isopropanol, and n-propyl alcohol. According to some examples of the present application, the organic solvent is ethanol.
According to some examples of the present application, the sintering temperature in step (1) is about 300° C. to 800° C. According to some examples of the present application, the sintering temperature in step (1) is about 400° C. to 700° C. According to some examples of the present application, the sintering temperature in step (1) is about 400° C. to 650° C.
According to some examples of the present application, the sintering time in step (1) is about 1 h to 20 h. According to some examples of the present application, the sintering time in step (1) is about 1 h to 15 h. According to some examples of the present application, the sintering time in step (1) is about 1 h to 10 h. According to some examples of the present application, the sintering time in step (1) is about 1.5 h to 5 h.
According to some examples of the present application, the sintering temperature in step (2) is about 700° C. to 1300° C. According to some examples of the present application, the sintering temperature in step (2) is about 700° C. to 1200° C. According to some examples of the present application, the sintering temperature in step (2) is about 800° C. to 1100° C.
According to some examples of the present application, the sintering time in step (2) is about 1 h to 20 h. According to some examples of the present application, the sintering time in step (2) is about 1 h to 15 h. According to some examples of the present application, the sintering time in step (2) is about 1 h to 10 h. According to some examples of the present application, the sintering time in step (2) is about 1.5 h to 5 h.
According to some examples of the present application, the sintering in both step (1) and step (2) is carried out under the protection of inert gas. According to some examples of the present application, the inert gas includes nitrogen, argon or a combination thereof.
According to some examples of the present application, the drying in step (1) and step (2) is spray drying, and the drying temperature is about 100° C. to 300° C.
During the preparation of the anode material of the present application, the pore-forming agent is used in the preparation method of the present application. Since the pore-forming agent used in the present application is an organic polymer, the pore-forming agent will produce residual carbons in the oxide MeOy layer after sintering. These residual carbons are favorable for increasing the conductivity of the oxide MeOy layer, thereby increasing the conductivity of the anode material.
As described above, based on the total weight of the silicon compound SiOx and the oxide MeOy layer, the content of the residual carbons in the MeOy layer is about 0.1 wt % to 1 wt %, about 0.2 wt % to 0.8 wt %, about 0.2 wt % to 0.6 wt % or about 0.2 wt % to 0.4 wt %.
On the other hand, the obtained oxide MeOy layer has pore structures due to the use of the pore-forming agent. The surface of the oxide MeOy layer adjacent to the carbon layer has open pore structures, and the carbon precursor can penetrate into at least part of these open pore structures, so that these open pore structures are filled with the carbon layer obtained after sintering. Therefore, the carbon layer is more tightly bonded to the oxide MeOy layer, and an interlocking effect is generated, thereby effectively enhancing the interfacial bonding force between the carbon and the substrate.
III. Anode
The examples of the present application provide an anode. The anode includes a current collector and an anode active material layer on the current collector. The anode active material layer includes the anode material according to the examples of the present application.
In some examples, the anode active material layer includes a binder. In some examples, the binder includes, but is not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethoxy-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene butadiene rubber, acrylic acid (esterified) butadiene styrene rubber, epoxy, and nylon.
In some examples, the anode active material layer contains a conductive material. In some examples, the conductive material includes, but is not limited to, natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, metal powder, metal fiber, copper, nickel, aluminum, silver, and polyphenylene derivatives.
In some examples, the current collector includes, but is not limited to, a copper foil, a nickel foil, a stainless steel foil, a titanium foil, nickel foam, copper foam, or a polymeric substrate coated with a conductive metal.
In some examples, the anode may be obtained by the following method: mixing the active material, the conductive material, and the binder in a solvent to prepare an active material composition, and coating the active material composition on the current collector.
In some examples, the solvent may include N-methylpyrrolidone or the like, but is not limited thereto.
IV. Cathode
The materials, compositions, and manufacturing methods capable of being used for a cathode in the examples of the present application include any of the technologies disclosed in the prior art. In some examples, the cathode is the cathode described in Patent Application U.S. Pat. No. 9,812,739B, which is incorporated herein in its entirety by reference.
In some examples, the cathode includes a current collector and a cathode active material layer on the current collector.
In some examples, the cathode active material includes, but is not limited to, lithium cobalt oxide (LiCoO2), lithium nickel cobalt manganese (NCM) ternary material, lithium iron phosphate (LiFePO4), and lithium manganate (LiMn2O4).
In some examples, the cathode active material layer further includes a binder, and optionally a conductive material. The binder increases the bonding among the particles of the cathode active material, and also improves the bonding between the cathode active material and the current collector.
In some examples, the binder includes, but is not limited to, polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethoxy-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene butadiene rubber, acrylic acid (esterified) styrene butadiene rubber, epoxy resin, nylon, etc.
In some examples, the conductive material includes, but is not limited to, a carbon-based material, a metal based material, a conductive polymer, and mixtures thereof. In some examples, the carbon-based material is selected from natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, or any combination thereof. In some examples, the metal-based material is selected from consisting of metal powder, metal fiber, copper, nickel, aluminum, and silver. In some examples, the conductive polymer is a polyphenylene derivative.
In some examples, the current collector may be aluminum, but is not limited thereto.
The cathode may be prepared by a preparing method well known in the art. For example, the cathode may be obtained by the following method: mixing the active material, the conductive material, and the binder in a solvent to prepare an active material composition, and coating the active material composition on the current collector. In some examples, the solvent may include N-methylpyrrolidone or the like, but is not limited thereto.
V. Electrolytic Solution
The electrolytic solution which can be used in the examples of the present application may be the electrolytic solution known in the art.
In some examples, the electrolytic solution includes an organic solvent, a lithium salt, and an additive. The organic solvent of the electrolytic solution according to the present application may be any organic solvent known in the art as a solvent for the electrolytic solution. The electrolyte used in the electrolytic solution according to the present application is not limited, and may be any electrolyte known in the art. The additive of the electrolytic solution according to the present application may be any additive known in the art as an additive of an electrolytic solution.
In some examples, the organic solvent includes, but is not limited to, ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), propylene carbonate and ethyl propionate.
In some examples, the lithium salt includes at least one of an organic lithium salt or an inorganic lithium salt.
In some examples, the lithium salt includes, but is not limited to, lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium difluorophosphate (LiPO2F2), lithium bistrifluoromethanesulfonimide LiN(CF3SO2)2(LiTFSI), lithium bis(fluorosulfonyl)imide Li(N(SO2F)2)(LiFSI), lithium bis(oxalate)borate LiB(C2O4)2(LiBOB), and lithium difluorooxalate borate LiBF2(C2O4)(LiDFOB).
In some examples, the concentration of the lithium salt in the electrolytic solution is: about 0.5 mol/L to 3 mol/L, about 0.5 mol/L to 2 mol/L, or about 0.8 mol/L to 1.5 mol/L.
VI. Separator
In some examples, a separator is disposed between the cathode and the anode to prevent a short circuit. The material and shape of the separator which can be used in the examples of the present application are not particularly limited, and can be any of the technologies disclosed in the prior art. In some examples, the separator includes a polymer or inorganic material or the like formed by a material that is stable with the electrolytic solution of the present application.
For example, the separator may include a substrate layer and a surface treatment layer. The substrate layer is a nonwoven fabric, a membrane or a composite membrane having a porous structure, and the material of the substrate layer is at least one selected from polyethylene, polypropylene, polyethylene terephthalate, and polyimide. Specifically, a polypropylene porous membrane, a polyethylene porous membrane, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite membrane may be used.
The surface treatment layer is disposed on at least one surface of the substrate layer, and the surface treatment layer may be a polymer layer or an inorganic layer, or may be a layer formed by mixing a polymer and an inorganic material.
The inorganic layer includes inorganic particles and a binder, and the inorganic particle is one or more selected from alumina, silica, magnesia, titania, ceria, tin oxide, ceria, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, cerium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, and barium sulfate. The binder is one or more selected from polyvinylidene fluoride, a copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, and polyhexafluoropropylene.
The polymer layer contains a polymer, and the material of the polymer is at least one selected from polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride, and poly(vinylidene fluoride-hexafluoropropylene).
VII. Electrochemical Device
The examples of the present application provide an electrochemical device that includes any device which has an electrochemical reaction.
In some examples, the electrochemical device according to the present application includes a cathode having a cathode active material capable of intercalating or releasing metal ions; an anode according to the examples of the present application; an electrolytic solution; and a separator between the cathode and the anode.
In some examples, the electrochemical device of the present application includes, but is not limited to, all types of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors.
In some examples, the electrochemical device is a lithium secondary battery.
In some examples, the lithium secondary battery includes, but is not limited to, a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.
VIII. Electronic Device
The electronic device according to the present application may be any device that uses the electrochemical device according to the examples of the present application.
According to some examples of the present application, the electronic device includes, but is not limited to, a notebook computer, a pen input type computer, a mobile computer, an e-book player, a portable phone, a portable fax machine, a portable copy machine, a portable printer, a headset, stereo headphones, a VCR, a LCD TV, a portable cleaner, a portable CD player, a mini disc, a transceiver, an electronic notebook, a calculator, a memory card, a portable recorder, a radio, a backup power device, a motor, a car, a motorcycle, a power bicycle, a bicycle, a lighting fixture, a toy, a game console, a clock, a power tool, a flashlight, a camera, a large household battery or a lithium ion capacitor.
Hereinafter, the lithium ion battery will be taken as an example and combined with specific examples to explain the preparation of the lithium ion battery. Those skilled in the art will understand that the preparation methods described in the present application are merely examples, and any other suitable preparation methods are all within the scope of the present application.
The performance evaluation of the lithium ion batteries of the examples and comparative examples according to the present application is explained below.
1. Preparation of Anode Material
The anode materials of Examples 1 to 8 and Comparative Examples 1 to 5 were prepared according to the method as follows:
The materials and process conditions used in each step were listed in Table 1. According to the anode material of the present application, the pore-forming agent PVP was added during the first preparation step, and since PVP is an organic polymer, residual carbon was generated after sintering. Therefore, in the sample obtained after the sintering in step (3), the residual carbon was distributed in the porous oxide layer. The content of the residual carbon in the porous oxide layer in each example was listed in Table 1. The content was measured after the sieving step of step (3), that is, calculated based on the total weight of the porous oxide-coated silicon-oxygen material.
2. The Powder Properties of the Anode Materials Obtained in Examples 1 to 8 and Comparative Examples 1 to 5 were Tested. The Powder Properties Testing Method were as Follows:
1.5 g to 3.5 g of a powder sample was placed into a test tube of a TriStar II 3020 and the specific surface area was tested after degassing at 200° C. for 120 min
The anode materials obtained in Examples 1 to 8 and Comparative Examples 1 to 5, the conductive carbon black and the binder PAA were mixed in a weight ratio of about 80:10:10, deionized water was added and stirred into the slurry. The slurry was scraped with a scraper blade to the coating with a thickness of about 100 μm, dried in a vacuum drying oven at about 85° C. for about 12 h, and cut into wafers having a diameter of about 1 cm by a punch in a dry environment. A lithium metal sheet was used as a counter electrode in a glove box. The separator was a celgard composite film. An electrolytic solution was added (the weight ratio of EC to DEC was equal to about 3:7, the concentration of lithium hexafluorophosphate was about 1 M, and the FEC accounted for about 5 wt % of the electrolytic solution) so as to assemble into button batteries. The batteries were subjected to a charging and discharging test by using the LAND series battery tests to test the charging and discharging performances thereof.
The test results of the powder properties and electrical properties of the anode materials obtained in Examples 1 to 8 and Comparative Examples 1 to 5 were listed in Table 2.
The first efficiency in the table=the capacity corresponding to the charging cut-off voltage of 0.8 V/the capacity corresponding to discharging cut-off voltage of 0.005 V.
4. Anode Material Properties Evaluated on a Full Battery
The active material LiCoO2, conductive carbon black, and the binder polyvinylidene fluoride (PVDF) were fully stirred and mixed uniformly in a N-methylpyrrolidone solvent system in a weight ratio of about 96.7:1.7:1.6, and then coated on an Al foil, and dried and cold-pressed to obtain a cathode.
Graphite was mixed with the anode materials obtained in Examples 1 to 8 and Comparative Examples 1 to 5 in a certain weight ratio respectively to obtain a mixed powder having a gram capacity of 430 mAh/g. The mixed powder, the conductive agent acetylene black, and PAA were fully stirred in deionized water in a weight ratio of about 95:1.2:3.8, and uniformly mixed, coated on a Cu foil, dried and cold-pressed to obtain an anode.
A PE porous polymeric membrane was used as a separator. The cathode, the separator and the anode were stacked in order, so that the separator was between the cathode and anode to act as an isolator, and wound to obtain a bare battery. The bare battery was placed in an outer package, and injected with a well-prepared electrolytic solution (the weight ratio of EC to DEC was equal to about 3:7, the concentration of lithium hexafluorophosphate was about 1 M, and the FEC accounted for about 5 wt % of the electrolytic solution) and packaged. After formation, degassing, trimming and other processes, the full battery cell was obtained.
The test results were listed in Table 3.
The “-” represented that the capacity retention rate was below 30% or lower before 400 cycles.
The test results of Example 1, Example 2 and Example 6 and Comparative Example 4 show that the introduction of the Al2O3 layer as an intermediate layer in the anode material could remarkably improve the high temperature cycle life of the battery and could reduce the impedance of the battery. In Example 1, Example 2, and Example 6, by controlling the content of an alumina precursor, the Al2O3 layer having different coating thicknesses could be obtained. It can be seen that as the content of the precursor increased (i.e., as the thicknesses of the Al2O3 layer increased), the high temperature cycle performance of the battery firstly became better and then deteriorated, and the impedance gradually decreased as the thickness increased. Therefore, it can be seen that the content of the alumina precursor in Example 2 was the optimum content.
The test results of Example 3, Example 4 and Example 5 and Comparative Example 4 show that the introduction of the TiO2 layer as an intermediate layer in the anode material could also significantly improve the high temperature cycle life of the battery and reduce the impedance of the battery. In Example 3, Example 4, and Example 5, by controlling the content of a titanium precursor, the TiO2 layer having different coating thicknesses could be obtained. It can be seen that as the content of the precursor increased (i.e., as the thicknesses of the TiO2 layer increased), the high temperature cycle performance of the battery gradually deteriorated, perhaps because the thicker intermediate layer increased the risk of overall destruction and peeling of the material.
The test results of Example 1 and Example 3 show that in the case that the precursor contents were low (i.e., the thickness of the intermediate layer was small), the cycle performance of the battery with Al2O3 as the intermediate layer and the cycle performance of the battery with TiO2 as the intermediate layer had little difference, and the capacity retention rate of the battery with Al2O3 as the intermediate layer after 400 cycles was about 4% higher.
The test results of Example 2 and Example 4 show that the battery with Al2O3 as the intermediate layer had a capacity retention ratio of about 10% higher than that of the battery with TiO2 as the intermediate layer.
The test results of Example 5 and Example 6 show that when the content of the precursor was high, both the batteries with Al2O3 or TiO2 as the intermediate layer had good high temperature cycle performance, and the high temperature cycle performances of them had little difference.
The test results of Example 2 and Comparative Example 2 show that merely a coating of the intermediate layer with alumina could not significantly improve the high temperature cycle performance of the battery, and the capacity retention rate after 400 cycles was only about 54%, which was much lower than the capacity retention rate after 400 cycles (about 78%) of the battery containing an intermediate oxide layer and a carbon layer simultaneously. Meanwhile, the test results of Example 4 and Comparative Example 1 can also show that merely coating the intermediate layer with TiO2 could not achieve the same effect, either. Therefore, only the combination of the intermediate oxide layer and the carbon coating on the surface could improve the cycle performance of the material.
The test results of Example 2 and Comparative Example 4 show that the design of the intermediate Al2O3 layer could significantly improve the cycle performance of the battery. As can be seen from the cycle attenuation curves of Example 2 and Comparative Example 4 shown in
The test results of Example 4 and Comparative Example 4 show that the design of the intermediate TiO2 layer can also improve the high temperature cycle performance of the battery. The above test results can demonstrate that the design of the intermediate oxide layer can significantly improve the cycle performance of the battery.
The test results of Example 2 and Example 8 and Comparative Example 2 indicate that the high temperature cycle performance is relevant to the carbon content of the anode material. The higher carbon content is beneficial to improve the conductivity of the material, thereby significantly improving the cycle performance of the battery and reducing the impedance of the battery. However, due to the difficulty of the preparation process of the material, when the content of the carbon coating layer is high, the anode material is prone to adhesion agglomeration, and the carbon content in Example 2 is the optimal carbon content.
The test results of Examples 1 to 8 and Comparative Example 5 show that due to the combined effect of the introduction of the intermediate oxide layer and the coating of the surface carbon layer, the high temperature cycle performance and rate performance of the battery can be significantly improved, and the impedance is reduced.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201811541619.8 | Dec 2018 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2019/125945 | 12/17/2019 | WO |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2020/125621 | 6/25/2020 | WO | A |
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| Entry |
|---|
| Office Action issued on Aug. 31, 2023, in corresponding Vietnamese Application No. 1-2021-01746, 3 pages. |
| Examination Report issued on Feb. 12, 2022, in corresponding Australian Application No. 2019411630, 4 pages. |
| Notice of Acceptance issued on Jul. 11, 2022, in corresponding Australian Application No. 2019411630, 4 pages. |
| Notification to Grant Patent Right for Invention issued on Jul. 17, 2020, in corresponding Chinese Application No. 201811541619.8, 6 pages. |
| Supplementary European Search Report issued on Nov. 25, 2021, in corresponding European Application No. 19899657, 3 pages. |
| Examination Report issued on Jan. 20, 2022, in corresponding Indian Application No. 202127008177, 5 pages. |
| Office Action issued on Mar. 29, 2022, in corresponding Japanese Application No. 2021-512505, 8 pages. |
| Office Action issued on Sep. 27, 2022, in corresponding Japanese Application No. 2021-512505, 4 pages. |
| Decision to Grant a Patent issued on Mar. 7, 2023, in corresponding Japanese Application No. 2021-512505, 5 pages. |
| International Search Report and Written Opinion issued on Mar. 19, 2020 in corresponding International Application No. PCT/CN2019/125945; 10 pages. |
| Office Action issued on Mar. 18, 2020 in corresponding Chinese Application No. 201811541619.8; 20 pages. |
| Office Action issued on Jan. 21, 2021 in corresponding Chinese Application No. 202010870352.8; 22 pages. |
| Number | Date | Country | |
|---|---|---|---|
| 20220052327 A1 | Feb 2022 | US |
