CN114039026A - Cathode material for solid lithium ion battery and preparation method and application thereof - Google Patents

Cathode material for solid lithium ion battery and preparation method and application thereof Download PDF

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Publication number
CN114039026A
CN114039026A CN202111288305.3A CN202111288305A CN114039026A CN 114039026 A CN114039026 A CN 114039026A CN 202111288305 A CN202111288305 A CN 202111288305A CN 114039026 A CN114039026 A CN 114039026A
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negative electrode
lithium ion
solid
ion battery
state lithium
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莫方杰
孙化雨
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Envision Power Technology Jiangsu Co Ltd
Envision Ruitai Power Technology Shanghai Co Ltd
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Envision Power Technology Jiangsu Co Ltd
Envision Ruitai Power Technology Shanghai Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention provides a negative electrode material for a solid-state lithium ion battery, and a preparation method and application thereof. According to the invention, the liquid metal Ga or/and Hg is combined with the negative active material to prepare the negative material for the solid lithium ion battery, so that the volume change of the negative electrode in the charging and discharging process is relieved, the contact between the electrode and the solid electrolyte is optimized, and the solid lithium ion battery prepared by adopting the negative material for the solid lithium ion battery has higher first discharge capacity and cycle stability.

Description

Cathode material for solid lithium ion battery and preparation method and application thereof
Technical Field
The invention belongs to the technical field of lithium ion batteries, and relates to a negative electrode material for a solid-state lithium ion battery, and a preparation method and application thereof.
Background
The solid lithium ion battery is a lithium ion battery using solid electrolyte to replace traditional liquid electrolyte, and because the electrolyte does not contain liquid, flammable and explosive organic solvent, the solid lithium ion battery is in phase with the lithium ion batteryCompared with the prior art, the safety protection device has stronger safety performance and has wide application prospect in the fields of electric automobiles and large-scale energy storage. The negative electrode of a general lithium ion battery adopts a graphite electrode, and the theoretical specific capacity of the graphite is about 372mAh g-1In order to increase the energy density of the solid-state lithium ion battery, the solid-state lithium ion battery needs to be applied to a negative electrode material with high specific capacity.
The prior art discloses an all-solid-state battery with a silicon cathode, wherein the cathode contains 40 wt% to 53 wt% of silicon powder, and the silicon powder and a small amount of sulfide are laminated on a current collector to be used as the battery cathode, so that the all-solid-state battery is prepared. In another prior art scheme, inorganic particles such as titanium dioxide, silicon monoxide and iron oxide are coated on the surface of a metal lithium sheet as a composite film to serve as a battery cathode, and a solid battery is prepared, so that the deposition of lithium dendrites can be regulated and controlled, and the capacity and cycle performance of the battery are improved. In addition, in the prior art, materials such as carbon particles, carbon fibers and silicon oxide are compounded, so that the problems of low capacity of pure carbon materials and large volume change of silicon-based materials are solved, and the composite material has high specific capacity and first-week coulombic efficiency.
In the prior art, high-capacity negative electrode materials such as silicon-based materials and the like are adopted to improve the specific capacity of the solid-state lithium ion battery, but the materials have huge volume change in the charge and discharge processes, and taking a silicon negative electrode as an example, the materials are converted into a complete lithiation product Li22Si5After that, the volume expansion is about 400%, which results in poor contact with the solid electrolyte during delithiation and deterioration of the interface resistance; even if carbon and other materials are used for doping and cladding, phase separation is easy to generate in the circulating process, the preparation method is complex, and the high-temperature sintering in the preparation process is easy to influence the appearance of the materials, so that the capacity is reduced.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide a negative electrode material for a solid-state lithium ion battery, and a preparation method and application thereof. According to the invention, the liquid metal Ga or/and Hg is combined with the negative active material to prepare the negative material for the solid lithium ion battery, so that the volume change of the negative electrode in the charging and discharging process is relieved, the contact between the electrode and the solid electrolyte is optimized, and the solid lithium ion battery prepared by adopting the negative material for the solid lithium ion battery has higher first discharge capacity and cycle stability.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a negative electrode material for a solid-state lithium ion battery, comprising a liquid metal and a negative electrode active material, wherein the liquid metal comprises Ga or/and Hg.
The liquid metal in the present invention means a metal that is liquid at 30 ℃.
According to the invention, liquid metal Ga or/and Hg is added into the negative electrode of the solid lithium ion battery to prepare the solid lithium ion battery. The liquid metal has good conductivity and stability, and can relieve the volume change of the negative active material in the charging and discharging process after being combined with the negative active material, prevent the negative material from collapsing, enhance the stability of the interface with a solid electrolyte, and improve the first discharge capacity and the cycle performance of the solid lithium ion battery; meanwhile, the solid lithium ion battery generally works in an environment higher than room temperature, compared with other liquid metals, Ga or/and Hg have good fluidity, and can be uniformly combined with an electrode material to improve the interface performance of the material, and the Ga or/and Hg are always kept in a liquid state.
When the liquid metal in the present invention is a mixture of Ga and Hg, Ga and Hg may be mixed in any mass ratio in the mixture.
Preferably, the mass ratio of the liquid metal to the negative electrode active material is (5 to 50):100, for example, 5:100, 8:100, 10:100, 15:100, 20:100, 25:100, 30:100, 35:100, 40:100, 45:100 or 50:100, etc., preferably (25 to 35):100, and the electrochemical performance of the solid-state lithium ion battery is better in a preferred range.
In a preferred embodiment of the present invention, the liquid metal is Ga.
According to the invention, the liquid metal Ga has better fluidity and lighter weight, and can be used in the negative electrode independently to relieve the volume change of the negative electrode in the charging and discharging processes, optimize the contact effect of the electrode and the solid electrolyte and improve the electrochemical performance of the solid lithium ion battery.
Preferably, the negative active material includes any one or a mixture of at least two of Si, Sn, P, Ge, Al, or Bi, and may be, for example, a mixture of Si and Sn, a mixture of Sn and P, a mixture of Al and Bi, a mixture of Si and P, a mixture of Si, Sn, and P, or a mixture of Si, Sn, P, and Ge, or the like.
When the anode active material of the present invention is a mixture, the raw materials in the mixture may be mixed in any ratio, for example, in a mixture of Si, Sn, and P, Si, Sn, and P may be mixed in any ratio.
Preferably, the average particle diameter D50 of the negative electrode active material is 0.2 μm to 4.5 μm, and may be, for example, 0.2 μm, 0.4 μm, 0.6 μm, 0.8 μm, 1.0 μm, 1.5 μm, 2.0 μm, 3 μm, 4 μm, or 4.5 μm, etc., within which the combination of the liquid metal and the negative electrode active material is more uniform and the electrochemical performance of the solid-state lithium ion battery is better.
In a second aspect, the present invention provides a method for preparing the negative electrode material for the solid-state lithium ion battery according to the first aspect, the method comprising:
and mixing the liquid metal and the negative active material in a ball milling manner to obtain the negative material for the solid lithium ion battery.
The state of the negative electrode active material is not limited in the present invention, and may be, for example, a powder.
In the prior art, liquid metal and a negative active material are generally mixed in a hydrothermal or sintering mode, but impurities are introduced or high-temperature deformation is generated in hydrothermal and sintering, so that the stability of a negative electrode is influenced.
In the invention, the liquid metals Ga and Hg have lower melting points, have good conductivity, fluidity and stability, and are liquid at the use temperature of the solid lithium ion battery, so that the liquid metals can act on the negative active material without hydrothermal or sintering steps, relieve the volume change of the negative active material in the charging and discharging process, prevent the structure of the negative active material from collapsing, enhance the stability of an interface with a solid electrolyte, improve the first discharge capacity and the cycle performance of the solid lithium ion battery, simultaneously prevent impurities from being introduced and high-temperature deformation from influencing the negative active material, and improve the stability of the negative electrode.
Preferably, the rotation speed of the ball mill is 200r/min to 500r/min, such as 200r/min, 250r/min, 300r/min, 350r/min, 400r/min, 450r/min or 500r/min, etc., preferably 350r/min to 450 r/min.
Preferably, the time for ball milling is 0.5h to 3h, for example, 0.5h, 0.6h, 0.8h, 1.0h, 1.2h, 1.5h, 1.8h, 2h, 2.5h or 3h, etc., preferably 0.8h to 1.5 h.
In a third aspect, the present invention provides a negative electrode, including a current collector and a negative electrode material layer disposed on at least one side surface of the current collector, where the negative electrode material layer includes the negative electrode material for the solid state lithium ion battery according to the first aspect.
Preferably, the negative electrode material layer further includes a conductive agent and a binder.
Preferably, the conductive agent comprises conductive carbon black.
Preferably, the binder comprises polyvinylidene fluoride.
Preferably, the mass ratio of the negative electrode material for the solid lithium ion battery, the conductive agent and the binder is (90 to 99): (0.8 to 1.2), wherein the selection range (90 to 99) of the negative electrode material for the solid lithium ion battery can be, for example, 90, 91, 92, 93, 94, 95, 96, 97, 98 or 99, etc., the selection range (0.8 to 1.2) of the conductive agent can be, for example, 0.8, 0.85, 0.9, 0.95, 1.0, 1.1 or 1.2, etc., and the selection range (0.8 to 1.2) of the binder can be, for example, 0.8, 0.85, 0.9, 0.95, 1.0, 1.1 or 1.2, etc., preferably (98 to 99): 0.9 to 1.0): 0: 0.9 to 1.0).
In a fourth aspect, the present invention provides a method for producing the anode according to the third aspect, the method comprising:
preparing a negative electrode material for a solid-state lithium ion battery by using the preparation method according to the second aspect;
preparing cathode slurry by adopting the cathode material for the solid-state lithium ion battery; and
and coating the negative electrode slurry on the surface of a current collector, and drying to obtain the negative electrode.
Preferably, in the step of preparing the anode slurry, a conductive agent and a binder are further added.
In a fifth aspect, the present invention provides a method for producing the anode according to the third aspect, the method comprising:
preparing cathode slurry by adopting liquid metal and a cathode active material; and
and coating the negative electrode slurry on the surface of a current collector, and drying to obtain the negative electrode.
Preferably, in the step of preparing the anode slurry, a conductive agent and a binder are further added.
In the invention, the liquid metal and the negative electrode active material can be mixed in a ball milling mode and then used for the negative electrode, or can be added respectively in the step of preparing the negative electrode slurry, and the liquid metal can act on the negative electrode active material by adopting the two modes, so that the good conductivity, stability and fluidity of the liquid metal are exerted, and the effects of relieving the volume change of the negative electrode active material in the charging and discharging process, preventing the structure collapse of the negative electrode material, enhancing the stability of the interface with a solid electrolyte and improving the first discharge capacity and the cycle performance of the solid lithium ion battery are achieved.
In a sixth aspect, the invention provides a solid-state lithium ion battery, which comprises a positive electrode, a negative electrode and a solid-state electrolyte layer, wherein the negative electrode adopts the negative electrode according to the third aspect.
The solid lithium ion battery is prepared by adopting the negative electrode compounded with the liquid metal Ga or/and Hg, the preparation method is simple, and the prepared solid lithium ion battery has higher first discharge capacity and better cycle stability.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, liquid metal Ga or/and Hg is added into the negative electrode of the solid lithium ion battery to prepare the solid lithium ion battery. The liquid metal has good conductivity and stability, and can relieve the volume change of the negative active material in the charging and discharging process after being combined with the negative active material, prevent the negative material from collapsing, enhance the stability of the interface with a solid electrolyte, and improve the first discharge capacity and the cycle performance of the solid lithium ion battery; meanwhile, the solid-state lithium ion battery generally works in an environment higher than room temperature, and compared with other liquid metals, Ga or/and Hg have good fluidity, and can be uniformly combined with an electrode material, so that the interface performance of the material is improved, the interface contact between an electrode and a solid electrolyte is improved, and the electrochemical performance of the solid-state lithium ion battery is further improved.
Drawings
Fig. 1 is a graph of the first discharge capacity of the solid state lithium ion batteries of example 1 and comparative example 1.
Fig. 2 is a graph of capacity retention for 100 cycles of the solid state lithium ion batteries of example 1 and comparative example 1.
Detailed Description
The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
In the prior art, high-capacity negative electrode materials such as silicon-based materials and the like are adopted to improve the specific capacity of the solid-state lithium ion battery, but the materials have huge volume change in the charge and discharge processes, and taking a silicon negative electrode as an example, the materials are converted into a complete lithiation product Li22Si5After that, the volume expansion is about 400%, which results in poor contact with the solid electrolyte during delithiation and deterioration of the interface resistance; even if carbon and other materials are used for doping and cladding, phase separation is easy to generate in the circulating process, the preparation method is complex, and the appearance of the material is easily influenced by high temperature, so that the capacity is reduced.
In order to solve the problems, the invention provides a negative electrode material for a solid-state lithium ion battery, and a preparation method and application thereof.
Embodiments of the present invention provide, in part, a negative electrode material for a solid state lithium ion battery, including a liquid metal including Ga or/and Hg and a negative electrode active material.
According to the invention, the liquid metal Ga or/and Hg is combined with the negative active material to prepare the negative material for the solid lithium ion battery, so that the volume change of the negative electrode in the charging and discharging process is relieved, the contact between the electrode and the solid electrolyte is optimized, and the solid lithium ion battery prepared by adopting the negative material for the solid lithium ion battery has higher first discharge capacity and cycle stability.
In some embodiments, the mass ratio of the liquid metal and the anode active material is (5 to 50):100, preferably (25 to 35): 100.
In some embodiments, the liquid metal is Ga.
In some embodiments, the negative active material includes any one or a mixture of at least two of Si, Sn, P, Ge, Al, or Bi.
In some embodiments, the average particle diameter D50 of the negative electrode active material is 0.2 μm to 4.5 μm.
Another embodiment provides a preparation method of the above negative electrode material for a solid-state lithium ion battery, including:
and mixing the liquid metal and the negative active material in a ball milling manner to obtain the negative material for the solid lithium ion battery.
In some embodiments, the rotational speed of the ball mill is from 200r/min to 500r/min, preferably from 350r/min to 450 r/min.
In some embodiments, the time for ball milling is from 0.5h to 3h, preferably from 0.8h to 1.5 h.
The embodiment of the invention also provides a negative electrode, which comprises a current collector and a negative electrode material layer arranged on at least one side surface of the current collector, wherein the negative electrode material layer comprises the negative electrode material for the solid-state lithium ion battery.
In some embodiments, the negative electrode material layer further comprises a conductive agent and a binder.
In some embodiments, the conductive agent comprises conductive carbon black.
In some embodiments, the binder comprises polyvinylidene fluoride.
In some embodiments, the mass ratio of the negative electrode material, the conductive agent and the binder for the solid-state lithium ion battery is (90 to 99): (0.8 to 1.2), preferably (98 to 99): (0.9 to 1.0).
The invention is not limited to the positive electrode and the solid electrolyte of the solid lithium ion battery, and in some embodiments, the positive electrode includes a layered positive electrode material and/or lithium iron phosphate.
In some embodiments, the layered positive electrode material has a chemical composition of LiNixCoyMn1-x-yO2Wherein x is more than or equal to 0.5 and less than or equal to 1, and y is more than or equal to 0 and less than or equal to 0.2.
In some embodiments, the solid electrolyte of the solid-state lithium-ion battery includes any one of or a combination of at least two of garnet-type oxides, diglyenite, or lithium borohydride.
In some embodiments, the garnet-type oxide comprises Li7La3Zr2O12。
In some embodiments, the digermite comprises Li6PS5Cl。
Example 1
The embodiment provides a negative electrode material and a negative electrode for a solid-state lithium ion battery, wherein the negative electrode material comprises liquid metal and a negative electrode active material, the liquid metal is Ga, the negative electrode active material is Si, the average grain diameter D50 of the Si is 2.1 mu m, and the mass ratio of the Ga to the Si is 30: 100; the negative electrode comprises the negative electrode material for the solid-state lithium ion battery, conductive carbon black and polyvinylidene fluoride, and the mass ratio of the negative electrode material for the solid-state lithium ion battery to the conductive carbon black to the polyvinylidene fluoride is 99:1: 1.
The embodiment also provides a preparation method of the anode, which comprises the following steps:
(1) preparing a negative electrode material for a solid-state lithium ion battery: mixing Ga powder and Si powder in a mass ratio of 30:100 in a ball milling mode, wherein the ball milling rotation speed is 400r/min, and the ball milling time is 1h to obtain a negative electrode material for a solid lithium ion battery;
(2) preparing a negative electrode: dispersing and stirring conductive carbon black, NMP and polyvinylidene fluoride at a high speed for 2h to prepare negative conductive slurry, then stirring and mixing the negative material for the solid lithium ion battery in the step (1) and the negative conductive slurry at a high speed to prepare negative slurry with certain viscosity, uniformly coating the prepared negative slurry on copper foil by using a scraper, drying the copper foil in a 70 ℃ blast drying oven for 40min, and then rolling and cutting to prepare a negative electrode;
the mass ratio of the negative electrode material for the solid-state lithium ion battery, the conductive carbon black, NMP and polyvinylidene fluoride is 99:1:40: 1.
Example 2
The embodiment provides a negative electrode material and a negative electrode for a solid-state lithium ion battery, wherein the negative electrode material for the solid-state lithium ion battery comprises a liquid metal and a negative electrode active material, the liquid metal comprises Hg, the negative electrode active material comprises Si and P, the average particle sizes D50 of the Si and the P are respectively 3.3 μm and 2.4 μm, and the mass ratio of Hg, Si and P is 25:50: 50; the negative electrode comprises the negative electrode material for the solid-state lithium ion battery, conductive carbon black and polyvinylidene fluoride, and the mass ratio of the negative electrode material for the solid-state lithium ion battery to the conductive carbon black to the polyvinylidene fluoride is 98.8:1: 1.
The embodiment also provides a preparation method of the anode, which comprises the following steps:
hg, Si powder and P powder in a mass ratio of 25:50:50 are used as a negative electrode material for a solid-state lithium ion battery, and are dispersed and stirred with conductive carbon black, NMP and polyvinylidene fluoride at a high speed for 2 hours to prepare negative electrode slurry with certain viscosity; uniformly coating the prepared cathode slurry on a copper foil by using a scraper, drying the copper foil in a 70 ℃ forced air drying oven for 40min, and then rolling and cutting to prepare a cathode;
the mass ratio of the negative electrode material for the solid-state lithium ion battery, the conductive carbon black, NMP and polyvinylidene fluoride is 98.8:1:40: 1.
Example 3
The embodiment provides a negative electrode material and a negative electrode for a solid-state lithium ion battery, wherein the negative electrode material for the solid-state lithium ion battery comprises a liquid metal and a negative electrode active material, the liquid metal comprises Ga, the negative electrode active material comprises Si and Sn, the average particle diameters D50 of the Si and the Sn are respectively 2.1 mu m and 1.2 mu m, and the mass ratio of the Ga to the Si to the Sn is 35:50: 50; the negative electrode comprises the negative electrode material for the solid-state lithium ion battery, conductive carbon black and polyvinylidene fluoride, and the mass ratio of the negative electrode material for the solid-state lithium ion battery to the conductive carbon black to the polyvinylidene fluoride is 99:1: 1.
The embodiment also provides a preparation method of the anode, which comprises the following steps:
(1) preparing a negative electrode material for a solid-state lithium ion battery: mixing Ga powder, Si powder and Sn powder in a mass ratio of 35:50:50 in a ball milling mode, wherein the rotating speed of the ball milling is 400r/min, and the ball milling time is 1h to obtain a negative electrode material for the solid lithium ion battery;
(2) preparing a negative electrode: dispersing and stirring conductive carbon black, NMP and polyvinylidene fluoride at a high speed for 2h to prepare negative conductive slurry, then stirring and mixing the negative material for the solid lithium ion battery in the step (1) and the negative conductive slurry at a high speed to prepare negative slurry with certain viscosity, uniformly coating the prepared negative slurry on copper foil by using a scraper, drying the copper foil in a 70 ℃ blast drying oven for 40min, and then rolling and cutting to prepare a negative electrode;
the mass ratio of the negative electrode material for the solid-state lithium ion battery, the conductive carbon black, NMP and polyvinylidene fluoride is 99:1:40: 1.
Example 4
The procedure was as in example 1 except that the liquid metal was replaced with Ga and Hg at a mass ratio of 1: 1.
Example 5
The same as example 1 except that the mass ratio of Ga to Si was 10: 100.
Example 6
The same as example 1 except that the mass ratio of Ga to Si was 45: 100.
Comparative example 1
The same as example 1 except that the negative electrode did not contain a liquid metal.
Comparative example 2
The procedure was as in example 1 except that the liquid metal was replaced with a gallium-niobium alloy.
A solid-state lithium ion battery was prepared using the negative electrodes of examples 1 to 6 and comparative examples 1 to 2, the preparation method of the solid-state lithium ion battery including:
(1) preparation of the positive electrode: dispersing and stirring conductive carbon black, a conductive carbon tube, NMP and polyvinylidene fluoride at a high speed for 2h to prepare positive conductive slurry, and then adding secondary spherical LiNi0.81Co0.09Mn0.1O2Stirring and mixing the slurry and the anode conductive slurry at a high speed to prepare anode slurry with certain viscosity; uniformly coating the prepared slurry on an aluminum foil by using a scraper, drying the aluminum foil in a 120 ℃ forced air drying oven for 20min, and then rolling and cutting the aluminum foil to prepare a positive electrode;
wherein, LiNi is a secondary sphere0.81Co0.09Mn0.1O2The mass ratio of the conductive carbon black to the conductive carbon tube to the NMP to the polyvinylidene fluoride is 97.5:1:0.5:40: 1.
(2) Preparing a solid lithium ion battery: mixing Li6PS5The Cl powder was pressed under a pressure of 15MPa to prepare a solid electrolyte, and then pressed under a pressure of 200MPa with the negative electrodes of examples 1 to 6 and comparative examples 1 to 2 and the positive electrode described in step (1), to obtain a solid lithium ion battery of 0.1 Ah.
The solid-state lithium ion batteries prepared using the negative electrodes of examples 1 to 6 and comparative examples 1 to 2 were charged at 60 ℃ to 4.2V at a current of 0.01A and then discharged at 2.5V at a current of 0.01A to obtain a first discharge capacity, denoted as C0(ii) a Then, at 60 ℃, at the current of 0.02A, the charge-discharge cycle is carried out in the voltage range of 2.5V to 4.2V, and the discharge capacity C is obtained after 100 cycles1，C1/C0Namely the capacity retention rate of the solid lithium ion battery after being circulated for 100 weeks; the first discharge capacity and the capacity retention rate at 100 cycles of the solid lithium ions of examples 1 to 6 and comparative examples 1 to 2 are shown in table 1.
TABLE 1
First discharge capacity (Ah) Capacity retention (%) at 100 weeks of circulation
Example 1 0.094 85
Example 2 0.088 82
Example 3 0.091 79
Example 4 0.092 83
Example 5 0.086 63
Example 6 0.087 73
Comparative example 1 0.085 23
Comparative example 2 0.083 36
It can be known from the above examples 1 to 6 that the liquid metal Ga or/and Hg is compounded in the negative electrode of the solid-state lithium ion battery, so that the volume change of the negative electrode in the charging and discharging processes is alleviated, and the contact between the electrode and the solid electrolyte is optimized, thereby improving the first discharge capacity and the cycle stability of the solid-state lithium ion battery.
As can be seen from the comparison among examples 1, 4 and 2, the selection of the liquid metal in the invention affects the electrochemical performance of the prepared solid lithium ion battery; when the liquid metal is Ga, the liquid metal and the cathode active material have better bonding performance, and the interface is more stable, so the first discharge capacity and the cycling stability of the embodiment 1 are higher than those of the embodiment 4; when the liquid metal is gallium-niobium alloy, the melting point of the liquid metal is higher, the dispersion effect is poorer at the working temperature of the solid lithium ion battery, and the gallium-niobium alloy can generate solid-liquid phase separation in the circulating process and has poorer contact with the interface of a negative active material and a solid electrolyte, so the technical effect of the invention cannot be achieved by selecting the liquid metal alloy in the comparative example 2.
As can be seen from the comparison between example 1 and examples 5 to 6, the mass ratio of the negative active material of the liquid metal affects the electrochemical performance of the prepared solid lithium ion battery; when the liquid metal content is higher or lower, the capacity exertion and cycle stability of the battery may be reduced.
Fig. 1 is a graph of the first discharge capacity of the solid-state lithium ion batteries of example 1 and comparative example 1, and it can be seen from fig. 1 that when Ga is compounded on the negative electrode of the solid-state lithium ion battery, the capacity can reach 0.094Ah, while the capacity of comparative example 1 is only 0.085Ah, and it can be seen that the first discharge capacity of the solid-state lithium ion battery can be increased by compounding liquid metal Ga on the negative electrode; fig. 2 is a graph of capacity retention rate of the solid-state lithium ion batteries of example 1 and comparative example 1 after cycling for 100 weeks, when the negative electrode is compounded with Ga, 85% of capacity retention rate of the solid-state lithium ion battery is still maintained for 100 weeks, while comparative example 1 is only 23%, and it is known that the capacity retention rate of the battery is greatly improved after the negative electrode is improved by liquid metal Ga.
The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.

Claims (10)

1. The negative electrode material for the solid lithium ion battery is characterized by comprising a liquid metal and a negative electrode active material, wherein the liquid metal comprises Ga or/and Hg.
2. The negative electrode material for the solid state lithium ion battery according to claim 1, wherein the mass ratio of the liquid metal to the negative electrode active material is (5 to 50):100, preferably (25 to 35): 100.
3. The negative electrode material for a solid-state lithium ion battery according to claim 1 or 2, wherein the liquid metal is Ga.
4. The negative electrode material for a solid-state lithium ion battery according to any one of claims 1 to 3, wherein the negative electrode active material comprises any one or a mixture of at least two of Si, Sn, P, Ge, Al, or Bi;
preferably, the average particle diameter D50 of the anode active material is 0.2 μm to 4.5 μm.
5. A preparation method of the negative electrode material for the solid-state lithium ion battery according to any one of claims 1 to 4, characterized by comprising:
and mixing the liquid metal and the negative active material in a ball milling manner to obtain the negative material for the solid lithium ion battery.
6. The preparation method of the negative electrode material for the solid-state lithium ion battery according to claim 5, wherein the rotation speed of the ball milling is 200r/min to 500r/min, preferably 350r/min to 450 r/min;
preferably, the time for ball milling is 0.5h to 3h, preferably 0.8h to 1.5 h.
7. A negative electrode, characterized in that the negative electrode comprises a current collector and a negative electrode material layer arranged on at least one side surface of the current collector, wherein the negative electrode material layer comprises the negative electrode material for the solid state lithium ion battery according to any one of claims 1 to 4;
preferably, the negative electrode material layer further comprises a conductive agent and a binder;
preferably, the conductive agent comprises conductive carbon black;
preferably, the binder comprises polyvinylidene fluoride;
preferably, the mass ratio of the negative electrode material, the conductive agent and the binder for the solid-state lithium ion battery is (90 to 99): (0.8 to 1.2), preferably (98 to 99): (0.9 to 1.0).
8. A method for producing the anode according to claim 7, characterized by comprising:
preparing a negative electrode material for a solid-state lithium ion battery by using the preparation method according to claim 5 or 6;
preparing cathode slurry by adopting the cathode material for the solid-state lithium ion battery; and
coating the negative electrode slurry on the surface of a current collector, and drying to obtain a negative electrode;
preferably, in the step of preparing the anode slurry, a conductive agent and a binder are further added.
9. A method for producing the anode according to claim 7, characterized by comprising:
preparing cathode slurry by adopting liquid metal and a cathode active material; and
coating the negative electrode slurry on the surface of a current collector, and drying to obtain a negative electrode;
preferably, in the step of preparing the anode slurry, a conductive agent and a binder are further added.
10. A solid-state lithium ion battery comprising a positive electrode, a negative electrode and a solid-state electrolyte layer, wherein the negative electrode employs the negative electrode according to claim 7.
CN202111288305.3A 2021-11-02 2021-11-02 Cathode material for solid lithium ion battery and preparation method and application thereof Pending CN114039026A (en)

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