An organic polymer-inorganic ceramic composite solid electrolyte, and a preparation method and application thereof

Abstract

The application relates to an organic polymer-inorganic ceramic composite solid electrolyte, and belongs to the technical field of solid-state secondary batteries.The organic polymer-inorganic ceramic composite solid electrolyte comprises the following components in percentage by mass: photocuring glue 1-30%, linear polymer 1-30%, inorganic ceramic filler 5-50%, plasticizer 10-90% and LiTFSI electrolyte salt 5-50%.The organic polymer-inorganic ceramic composite solid electrolyte has good low-temperature performance, the lithium ion conductivity at room temperature exceeds 10 ‑5 S cm ‑1 orders of magnitude, has good cycle performance, and when applied to a solid-state secondary battery, can still maintain good electrochemical performance in a wide temperature range of 25-100 DEG C, and the positive electrode material capacity at high temperature reaches 140mAh g ‑1 .

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of solid-state secondary batteries, and relates to an organic polymer-inorganic ceramic composite solid-state electrolyte and a preparation method and application thereof. BACKGROUND

[0002] Lithium ion batteries are widely used in 3C digital, electric tools, new energy vehicles and electrochemical energy storage power stations and other fields in recent years due to their high energy density, long cycle life, no memory effect and other advantages. However, with the increasing demand and the continuous improvement of technical requirements, the existing lithium ion battery system cannot fully meet various application scenarios, and it is necessary to further improve the energy density, cycle life and safety of the battery. In addition, the lithium ion batteries commonly used in the market at present, whether 3C batteries or power batteries, adopt liquid electrolytes of LiPF6 and organic carbonate systems. The liquid electrolyte is easy to leak, and the organic solvent is flammable and volatile, which can easily cause fire accidents. Solid-state batteries using solid-state electrolytes do not have flowing electrolytes, so they can avoid problems such as electrolyte leakage and electrolyte combustion, and are the ultimate solution to the safety of lithium ion batteries.

[0003] In recent years, domestic and foreign scientific researchers have carried out a large amount of research work on solid-state electrolytes. At present, inorganic solid-state electrolytes represented by olivine, NASICON-type oxides and LiPON and organic polymer solid-state electrolytes represented by PEO have obtained good performance. Although inorganic ceramic solid-state electrolytes have good mechanical strength and thermal stability, they have the problems of brittle material, easy breakage, large contact impedance with electrode materials, and easy peeling of electrode-electrolyte interface in the cycle process due to the change of electrode thickness. Organic polymer solid-state electrolytes have good flexibility and good electrode-electrolyte interface contact, and can be processed into flexible batteries for wearable devices. However, they usually have low lithium ion conductivity at room temperature (<10 -6 S cm -1 ), and need to be heated to work normally.

[0004] Organic-inorganic composite solid electrolyte has the advantages of both inorganic ceramic solid electrolyte and organic polymer electrolyte, and thus has better application prospect. The organic-inorganic composite system generally refers to a composite system formed by adding some inorganic fillers to a polymer electrolyte. The inorganic fillers can be divided into inert fillers and active fillers. The inert fillers are commonly Al2O3, SiO2 and TiO2, which do not directly participate in the ion transmission process, but through the Lewis acid-base interaction of the inert fillers with the polymer matrix and lithium salt, the crystallinity of the polymer matrix can be reduced, the dissociation of lithium salt can be promoted, the number of free Li ions can be increased, and the fast transmission channel of Li ions can be increased, so as to improve the ionic conductivity. The active fillers generally refer to inorganic solid electrolytes (divided into oxides and sulfides), which can directly participate in ion transmission and provide lithium source to further improve the ionic conductivity.

[0005] Although good experimental results have been achieved in the field of solid-state lithium ion batteries by using organic polymer-inorganic ceramic composite solid electrolyte in recent years, some key problems such as narrow redox electrochemical window of electrolyte and poor low-temperature performance and mechanical performance have not been solved. SUMMARY

[0006] The purpose of the present application is to overcome the deficiencies of the prior art and provide an organic polymer-inorganic ceramic composite solid electrolyte with good low-temperature performance, and a preparation method and application thereof.

[0007] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0008] In a first aspect, the present application provides an organic polymer-inorganic ceramic composite solid electrolyte, which comprises the following components in mass percentage: photocuring glue 1% to 30%, linear polymer 1% to 30%, inorganic ceramic filler 5% to 50%, plasticizer 10% to 90%, and LiTFSI electrolyte salt 5% to 50%.

[0009] By selecting a specific component ratio and adding inorganic ceramic fillers, the crystallinity of the polymer can be effectively reduced through Lewis acid-base effect, and the melting point of the electrolyte can be reduced by adding plasticizer, so as to obtain a lower glass transition temperature (T g ). Since lithium ion transmission mainly occurs in the amorphous region of the polymer, the obtained organic polymer-inorganic ceramic composite solid electrolyte can have good low-temperature performance, and the lithium ion conductivity thereof at room temperature is more than 10 -5 S cm -1 order of magnitude.

[0010] As a preferred embodiment of the present invention, the organic polymer-inorganic ceramic composite solid electrolyte comprises the following components by mass percentage: 10% to 20% photocurable adhesive, 2% to 10% linear polymer, 10% to 30% inorganic ceramic filler, 40% to 65% plasticizer, and 10% to 20% LiTFSI electrolyte salt.

[0011] Under the preferred ratio range, the organic polymer-inorganic ceramic composite solid electrolyte of the present invention has better low-temperature performance.

[0012] In a preferred embodiment of the present invention, the photocurable adhesive includes at least one of NOA61, NOA63, NOA65, NOA68, NOA73, NOA76, NOA81, NOA83, NOA86, NOA88, and NOA160.

[0013] The photocurable adhesive selected in this invention has the characteristics of fast curing rate (about a few seconds), high mechanical strength and good flexibility of the cured polymer, which can effectively avoid the occurrence of interfacial peeling and cracking of solid electrolytes during cycling.

[0014] In a preferred embodiment of the present invention, the linear polymer includes at least one of composite polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polytetrafluoroethylene (PTFR), polyethylene oxide (PEO), polymethyl methacrylate (PMMA), polyacrylonitrile polyacrylonitrile (PAN), and polyurethane (PI).

[0015] In a preferred embodiment of the present invention, the inorganic ceramic filler includes at least one of Al2O3, SiO2, TiO2, olivine oxide, NASICON oxide and LiPON.

[0016] The olivine-type oxide includes Li7La3Zr2O 12 Li 6.4 La3Zr 1.4 Ta 0.6 O 12 Li x Al y La3Zr2O 12 Where 6≤x≤12, 0≤y≤1;

[0017] The NASICON-type oxide includes Na 1+x Zr2P 3-x Si x O 12 , of which 0 <x<3;

[0018] The LiPON comprises Li6PS5X, wherein X = Cl, Br or I.

[0019] As a preferred embodiment of the present application, the plasticizer comprises at least one of succinonitrile (SN), suberontirile (SBN) and organic carbonate.

[0020] As a preferred embodiment of the present application, the organic polymer-inorganic ceramic composite solid electrolyte further comprises a lithium supplementing agent in a mass percentage of 0% to 30%.

[0021] The lithium supplementing agent comprises at least one of Li4FeO5, Li6CoO4, Li2NiO2 and metallic lithium.

[0022] In a second aspect, the present application provides a preparation method of the above organic polymer-inorganic ceramic composite solid electrolyte, comprising the following steps:

[0023] S1, adding a photocuring glue and a linear polymer to a LiTFSI electrolyte salt, mixing uniformly, then adding an inorganic ceramic filler and a plasticizer, stirring uniformly, preparing a semi-solid electrolyte slurry, and reserving;

[0024] S2, constructing an organic polymer-inorganic ceramic composite solid electrolyte by ultraviolet light curing of the prepared semi-solid electrolyte slurry.

[0025] In a third aspect, the present application provides an application of the above organic polymer-inorganic ceramic composite solid electrolyte in a solid-state secondary battery.

[0026] The solid-state secondary battery comprises a positive electrode, a solid electrolyte and a negative electrode.

[0027] The solid electrolyte is the organic polymer-inorganic ceramic composite solid electrolyte.

[0028] Compared with the prior art, the present application has the following beneficial effects: the composite solid electrolyte prepared by the organic polymer-inorganic ceramic formula in the present application has good low-temperature performance, and the lithium ion conductivity at room temperature exceeds 10 -5 S cm -1 orders of magnitude. The solid-state lithium ion battery prepared by the solid electrolyte has a positive electrode gram capacity of 128 mAh g -1 under a 25℃ 0.2C test condition, and has good cycle performance. The battery still has good electrochemical performance in a wide temperature range of 25-100℃, and the gram capacity of the positive electrode material at high temperature reaches 140 mAh g -1 The above. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1The charge-discharge performance diagram of the solid-state lithium ion battery described in the present application in the temperature range of 25-100℃. DETAILED DESCRIPTION

[0030] For the purpose of better illustrating the object, technical scheme and advantages of the present application, the present application will be further described in combination with specific examples.

[0031] Example 1

[0032] An embodiment of the semi-solid electrolyte paste described in the present application, the preparation method of the semi-solid electrolyte paste described in the present application comprises the following steps:

[0033] Take 220mg of LiTFSI and dissolve it in 700mg of SBN to prepare a 1mol / L electrolyte solution, add it to a mortar, then add 240mg of NOA68 photocuring glue and 50mg of PVDF-HFP (France Arkema) to it, grind uniformly, then add 30mg of PEO polymer, continue to grind, mix uniformly, finally add 288mg of Li 10.7 Al 0.24 La3Zr2O 12 (LALZO) inorganic ceramic solid electrolyte powder, continue to grind uniformly, to prepare a semi-solid electrolyte paste, for standby use, the specific formula table is shown in Table 1.

[0034] Table 1

[0035] Material Mass Mass percentage LiTFSI 220 mg 14.4％ SBN 700 mg 45.8％ NOA68 240 mg 15.7％ PEO 30 mg 2.0％ PVDF-HFP 50 mg 3.3％ LALZO 288 mg 18.8％

[0036] Example 2

[0037] An embodiment of the semi-solid electrolyte paste described in the present application, the preparation method of the semi-solid electrolyte paste described in the present application comprises the following steps:

[0038] Take 220mg of LiTFSI and dissolve it in 700mg of SBN to prepare a 1mol / L electrolyte solution, add it to a mortar, then add 240mg of NOA68 photocuring glue and 50mg of PVDF-HFP (France Arkema) to it, grind uniformly, then add 30mg of PEO polymer, continue to grind, mix uniformly, finally add 288mg of Li 10.7 Al 0.24 La3Zr2O 12 (LALZO) inorganic ceramic solid electrolyte powder, continue to grind uniformly, to prepare a semi-solid electrolyte paste, for standby use, the specific formula table is shown in Table 1.

[0039] Table 2

[0040] Material Mass Mass percentage LiTFSI 220 mg 15.9％ SBN 700 mg 50.4％ NOA68 140 mg 10.1％ PEO 10 mg 0.7％ PVDF-HFP 30 mg 2.2％ LALZO 288 mg 20.7％

[0041] Example 3

[0042] Example 3 is different from Example 2 in that the raw material ratio is different, and the specific formula table is shown in Table 3.

[0043] Table 3

[0044] Material Mass Mass percentage LiTFSI 220 mg 18.0％ SBN 700 mg 57.1％ NOA68 140 mg 11.4％ PEO 10 mg 0.8％ PVDF-HFP 30 mg 2.5％ LALZO 125 mg 10.2％

[0045] Example 4

[0046] Example 4 is different from Example 2 in that the raw material ratio is different, and the specific formula table is shown in Table 4.

[0047] Table 4

[0048]

[0049]

[0050] Example 5

[0051] Example 5 is different from Example 2 in that Example 5 uses Al2O3 to replace the LALZO, and the others are the same.

[0052] Example 6

[0053] An embodiment of the organic polymer-inorganic ceramic composite solid-state electrolyte thin film according to the present application, a preparation method of the organic polymer-inorganic ceramic composite solid-state electrolyte thin film includes the following steps:

[0054] The semi-solid electrolyte slurry is printed on the surface of a LiNi1 / 3Mn1 / 3Co1 / 3O2(NMC111) positive electrode sheet using a silk screen mesh, and is cured using ultraviolet light (10W, distance 2cm), and the thickness of the semi-solid electrolyte is measured to be 30μm, and then the semi-solid electrolyte slurry is printed on the surface of a Li5Ti4O 12 (LTO) negative electrode sheet using the same method, and is cured using ultraviolet light, and the thickness of the semi-solid electrolyte is measured to be 25μm, and the prepared positive and negative electrode sheets are cut into circular sheets and bonded together to obtain an organic polymer-inorganic ceramic composite solid-state electrolyte thin film.

[0055] Example 7

[0056] An embodiment of the solid-state secondary battery according to the present application, a preparation method of the solid-state secondary battery according to the present embodiment includes the following steps:

[0057] 1. Preparation of battery positive and negative electrode sheets:

[0058] The solid-state secondary battery described in the embodiment is a solid-state lithium ion battery, and the positive and negative electrode sheets used in the solid-state lithium ion battery are prepared by using the conventional lithium ion battery electrode sheet preparation process.

[0059] 2. Assembled in the order of negative shell-steel sheet-negative electrode sheet-solid-state electrolyte-positive electrode sheet-steel sheet-spring sheet-positive shell, the assembled battery is pressed by a mold to prepare a 2032 type button cell.

[0060] Test Example 1

[0061] The solid-state electrolyte described in Example 2 is assembled into a solid-state lithium ion battery according to the method described in Example 7, and the lithium ion conductivity of the organic polymer-inorganic ceramic composite solid-state electrolyte described in the application at low temperature 25℃ is obtained by testing the electrochemical impedance of the solid-state lithium ion battery. 3x10 -5 S cm -1 The charge-discharge performance of the solid-state lithium ion battery described in the application in the temperature range of 25-100℃ is shown in Figure 1 , Figure 1 It can be seen that the solid-state lithium ion battery can still maintain good electrochemical performance in a wide temperature range of 25-100℃, and the specific capacity of the positive electrode material at high temperature reaches 140mAh g -1 .

[0062] Test Example 2

[0063] The solid-state electrolyte described in Examples 1-5 is assembled into a solid-state lithium ion battery according to the method described in Example 7, and the specific capacity and cycle performance of the solid-state lithium ion battery are tested under the test conditions of 25℃, 0.2C and 100℃, 0.2C. The test results are shown in Table 5, and the cycle life shown in Table 5 is the cycle number when the battery retention rate is 80%.

[0064] Table 5

[0065]

[0066] As can be seen from Table 5, the solid-state lithium ion battery described in the application has good cycle performance, among which the cycle performance of the solid-state lithium ion battery described in Example 2 is the best. The specific capacity of the positive electrode under the test conditions of 25℃, 0.2C can reach 128mAh g -1 , and the retention rate is 80% after 154 cycles; the specific capacity of the positive electrode under the test conditions of 100℃, 0.2C can reach 141mAh g -1 , and the retention rate is 80% after 20 cycles.

[0067] Finally, it should be noted that the above examples are merely intended to illustrate the technical solutions of the present application and not to limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present application.

Claims

1. An organic polymer-inorganic ceramic composite solid-state electrolyte, characterized by, The components include the following mass percentages: photocuring glue 8.9% to 10.1%, linear polymer 2.6% to 2.9%, inorganic ceramic filler 20.7% to 30%, plasticizer 44.5% to 50.4%, LiTFSI electrolyte salt 14% to 15.9%; The inorganic ceramic filler is Li 10.7 Al 0.24 La3Zr2O 12 The plasticizer is at least one of butanedinitrile, succindinitrile and organic carbonates. The photocuring glue includes at least one of NOA61, NOA63, NOA65, NOA68, NOA73, NOA76, NOA81, NOA83, NOA86, NOA88, and NOA160.

2. The organic polymer-inorganic ceramic composite solid-state electrolyte of claim 1, wherein, The linear polymer includes at least one of composite polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene, polyethylene oxide, polymethyl methacrylate, polyacrylonitrile, and polyurethane.

3. The organic polymer-inorganic ceramic composite solid-state electrolyte of claim 1, wherein the organic polymer is a poly(ethylene oxide) polymer. The lithium supplement agent also includes 0% to 30% by mass; The lithium supplement agent includes at least one of Li4FeO5, Li6CoO4, Li2NiO2, and metallic lithium.

4. The method for producing an organic polymer-inorganic ceramic composite solid electrolyte according to any one of claims 1 to 3, characterized by, The method includes the following steps: S1, adding photocuring glue and linear polymer to LiTFSI electrolyte salt, mixing uniformly, then adding inorganic ceramic filler and plasticizer, stirring uniformly, preparing semi-solid electrolyte slurry, and reserving; S2, preparing organic polymer-inorganic ceramic composite solid-state electrolyte by ultraviolet light curing of the prepared semi-solid electrolyte slurry.

5. Application of the organic polymer-inorganic ceramic composite solid-state electrolyte according to any one of claims 1-3 in a solid-state secondary battery.

6. A solid-state secondary battery characterized by The solid-state secondary battery includes a positive electrode, a solid-state electrolyte, and a negative electrode. The solid-state electrolyte is the organic polymer-inorganic ceramic composite solid-state electrolyte according to any one of claims 1-3.

Images