A porous mxene modified lithium ion battery solid electrolyte and a preparation method thereof

Abstract

The application discloses a kind of porous MXene modified lithium ion battery solid electrolyte and preparation method, by lithium battery polymer separator and the porous MXene microgel coated on it, preparation method includes: the porous MXene microgel is evenly coated on the front and back of lithium battery polymer separator, and is prepared by vacuum drying.The currently commercialized lithium battery polymer separator is coated by using porous MXene to form an integrated solid electrolyte, improve the existing solid electrolyte ion conductivity low, electrode and electrolyte interface is not friendly and so on Problem, so that solid lithium battery becomes possible.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium battery material preparation, and particularly relates to a porous MXene modified lithium ion battery solid electrolyte and a preparation method. BACKGROUND

[0002] In recent years, lithium ion batteries have developed rapidly. The lithium ion battery is a rechargeable battery that realizes mutual conversion between chemical energy and electrical energy through lithium ion intercalation and deintercalation between positive and negative electrodes, and has the characteristics of large energy density, high working voltage and long cycle life. However, the lithium ion batteries of the lithium iron phosphate / C and ternary material / C systems widely used at present adopt liquid organic electrolytes, the actual capacity of which has approached the theoretical limit. In the charging and discharging process, lithium dendrites are generated at the negative electrode, which may pierce the polypropylene separator, causing the battery to short circuit, and even cause the battery to catch fire in severe cases. These problems greatly limit the application of lithium ion batteries.

[0003] Compared with the traditional flammable organic liquid electrolyte, the solid-state battery uses a non-combustible solid-state electrolyte as an ion-conducting medium, which can improve the safety of the battery system, reduce the weight of the battery and improve the energy density of the battery. It is an effective way to solve the current problems of lithium ion batteries. The solid-state electrolyte used in the solid-state battery can be divided into three types according to the composition: (1) inorganic solid-state electrolyte, usually based on oxides and sulfides, such as LiTi(PO4) 3 , Li7La3Zr2O 12 , etc.; (2) polymer solid-state electrolyte, commonly used are polyether, polycarbonate, polyvinylidene fluoride, polysiloxane, etc., among which polyethylene oxide (PEO) is the most widely studied; (3) organic-inorganic composite solid-state electrolyte, such as PEO matrix doped with Li 1.5 Al 0.5 Ge 1.5 (PO4) 3 The solid-state electrolyte has many advantages, but it still faces many problems, such as low room temperature ionic conductivity, short cycle life, and unfriendly interface between electrode and electrolyte. These problems of the solid-state electrolyte seriously affect the development of solid-state lithium batteries. SUMMARY

[0004] Therefore, the present application provides a porous MXene modified lithium ion battery solid electrolyte and a preparation method. By using porous MXene to coat the current commercial lithium battery polymer separator to form an integrated solid-state electrolyte, the problems of low ionic conductivity of the existing solid-state electrolyte and unfriendly interface between electrode and electrolyte are improved, so that the solid-state lithium battery becomes possible.

[0005] According to the embodiment of the present application, a porous MXene modified lithium ion battery solid electrolyte is provided, which is composed of a lithium battery polymer separator and a porous MXene microgel coated thereon.

[0006] Preferably, the lithium battery polymer separator comprises one of microporous polyolefin separators mainly composed of polyethylene (PE) and polypropylene (PP), PVDF separators, polyimide separators, aramid resin separators, and ceramic separators, preferably microporous polyolefin separators.

[0007] Preferably, the porous MXene microgel is cross-linked from porous MXene nanosheets and cellulose.

[0008] Preferably, the preparation method of the porous Mxene microgel is as follows:

[0009] Step one, stir and disperse MXene nanosheets into a hydrogen peroxide solution, stir and etch, then centrifuge and wash the reacted solution, and ultrasonically disperse to obtain a porous MXene nanosheet solution;

[0010] Step two, add cellulose raw material to deionized water, crush and stir to make it fully dispersed and uniform, to obtain a cellulose dispersion;

[0011] Step three, add the porous MXene nanosheet solution to the cellulose dispersion and stir to obtain a cellulose-supported porous MXene microgel.

[0012] Preferably, the MXene nanosheet is preferably Ti3C2T x MXene material is a kind of metal carbon / nitride (transition metal carbide / nitride) with two-dimensional layered structure, and its chemical general formula is M n+1 X n T X , wherein (n = 1-3), M represents early transition metals such as Ti, Zr, V, Mo, etc.; X represents C or N element, T X is a surface group, usually -OH, -O, -F and -Cl. Due to its similar sheet structure to Graphene, it is named MXene.

[0013] Preferably, the mass ratio of the MXene nanosheet to the hydrogen peroxide solution is 0.1-1, and the mass concentration of the H2O2 solution is 0.01%-0.1%.

[0014] Preferably, the etching temperature is 20-80℃, and the etching time is 10-100min.

[0015] Preferably, the cellulose is selected from one or more of bacterial cellulose, nanocellulose, microfibrillated cellulose, oxidized cellulose.

[0016] Preferably, the mass ratio of the MXene nanosheet to the cellulose is 20:1 to 1:1.

[0017] Preferably, the mass percentage of the cellulose in the cellulose dispersion liquid is 0.5 to 4%.

[0018] Preferably, the preparation method of the lithium ion battery solid electrolyte comprises:

[0019] The porous MXene microgel is uniformly coated on the front and back surfaces of the lithium battery polymer separator, and is dried in vacuum to obtain.

[0020] Preferably, the thickness of the porous MXene microgel on the front and back surfaces of the lithium battery polymer separator after drying is 1 to 10 microns.

[0021] The technical scheme provided by the embodiment of the application can include the following beneficial effects:

[0022] The porous MXene modified lithium ion battery solid electrolyte has excellent mechanical properties, high heat resistance, large specific surface area and more ion channels, can break through the bottleneck of low energy density of lithium ion batteries on the market at present, improve the cycle stability, enhance the rate performance, and reduce the safety hazard.

[0023] In the porous MXene modified lithium ion battery solid electrolyte, the MXene layers are supported by the cellulose cross-linking, have large porosity and high mechanical properties, can solve the problem of unfriendly interface between the electrode material and the electrolyte through mechanical compaction, and can effectively alleviate the volume expansion of the positive and negative active materials, so that it is possible to use high-capacity positive and negative electrode materials (such as lithium sulfide, silicon-based materials, etc.).

[0024] The porous MXene modified lithium ion battery solid electrolyte has good ion transport performance, excellent mechanical properties, high stability and high safety, and can be applied to high-power / fast-charging lithium ion batteries to realize the application of high-power / fast-charging lithium ion battery solid electrolyte products.

[0025] The preparation method of the porous MXene microgel is simple, easy to control and low in cost, is green and pollution-free from raw material use to preparation process, and is beneficial to industrial large-scale production.

[0026] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the application. BRIEF DESCRIPTION OF DRAWINGS

[0027] The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate embodiments consistent with the application and, together with the description, further serve to explain the principles of the application.

[0028] Figure 1 A schematic diagram of a porous MXene modified lithium ion battery solid-state electrolyte according to an exemplary embodiment.

[0029] Wherein: 1, lithium battery polymer separator; 2, porous Mxene microgel. DETAILED DESCRIPTION

[0030] The exemplary embodiments will be described in detail hereinafter

[0031] Example 1

[0032] A method for preparing a porous MXene modified lithium ion battery solid-state electrolyte, specifically comprising the following steps:

[0033] First, a cellulose supported porous Mxene microgel material is prepared, the steps are as follows:

[0034] Step one, preparation of porous MXene nanosheet solution: take 20 parts by weight of Ti3C2T x nanosheets are dispersed by stirring into 200 parts by weight of 0.01% mass concentration hydrogen peroxide (H2O2) solution, and etched at 20°C for 10 minutes. Then the reacted solution is centrifuged and washed, and ultrasonically dispersed to obtain a porous MXene nanosheet solution.

[0035] Step two, preparation of cellulose dispersion: add 1 part by weight of bacterial cellulose raw material to 200 parts by weight of deionized water, and use a high-speed blender to break and stir at 15000 rpm to make it fully dispersed and uniform, to obtain a bacterial cellulose dispersion.

[0036] Step three, preparation of cellulose supported porous MXene: add the porous MXene nanosheet solution prepared in step one to the bacterial cellulose dispersion prepared in step two, and stir thoroughly to obtain a bacterial cellulose supported porous MXene microgel material.

[0037] Subsequently, a porous MXene modified lithium ion battery solid-state electrolyte is prepared, and the specific steps are as follows:

[0038] As Figure 1 shown, the above prepared cellulose supported porous MXene microgel 2 is uniformly coated on the front and back of the lithium battery polymer separator 1, and vacuum dried to obtain a porous MXene modified lithium ion battery solid-state electrolyte. After drying, the thickness of the MXene coating layer on the front and back of the separator is 1 μm.

[0039] Example 2

[0040] A method for preparing a porous MXene modified lithium ion battery solid-state electrolyte, specifically comprising the following steps:

[0041] First, a cellulose supported porous Mxene microgel material is prepared, and the steps are as follows:

[0042] Step one, preparation of a porous MXene nanosheet solution: take 10 parts by weight of Ti3C2T x Nanosheet is dispersed by stirring into 20 parts by weight of 0.05% mass concentration hydrogen peroxide (H2O2) solution, and etched at 50°C for 50 minutes. Then the reacted solution is centrifuged and washed, and ultrasonic dispersion is obtained to obtain a porous MXene nanosheet solution.

[0043] Step two, preparation of a cellulose dispersion: 1 part by weight of nanocellulose raw material is added to 50 parts by weight of deionized water, and a high-speed blender is used to break and stir at a speed of 20,000 rpm to make it fully dispersed and uniform, obtaining a nanocellulose dispersion.

[0044] Step three, preparation of cellulose supported porous MXene: the porous MXene nanosheet solution prepared in step one is added to the nanocellulose dispersion prepared in step two, and the nanocellulose supported porous MXene microgel material is obtained by stirring.

[0045] Subsequently, a porous MXene modified lithium ion battery solid-state electrolyte is prepared, and the specific steps are as follows:

[0046] The cellulose supported porous MXene microgel 2 prepared above is uniformly coated on the front and back of the lithium battery polymer separator 1, and vacuum dried to obtain a porous MXene modified lithium ion battery solid-state electrolyte. After drying, the thickness of the MXene coating layer on the front and back of the separator is 5 μm.

[0047] Example 3

[0048] A method for preparing a porous MXene modified lithium ion battery solid-state electrolyte, specifically comprising the following steps:

[0049] First, a cellulose supported porous Mxene microgel material is prepared, and the steps are as follows:

[0050] Step one, preparation of a porous MXene nanosheet solution: take 10 parts by weight of Ti3C2T x Nanosheet is dispersed by stirring into 20 parts by weight of 0.05% mass concentration hydrogen peroxide (H2O2) solution, and etched at 50°C for 50 minutes. Then the reacted solution is centrifuged and washed, and ultrasonic dispersion is obtained to obtain a porous MXene nanosheet solution.

[0051] Step two, preparation of cellulose dispersion liquid: 1 part by weight of oxidized cellulose raw material is diluted with 25 parts by weight of water, and is broken and stirred at a speed of 30000 rpm using a high-speed stirrer to make it fully dispersed and uniform, to obtain an oxidized cellulose dispersion liquid.

[0052] Step three, preparation of cellulose-supported porous MXene: the porous MXene nanosheet solution prepared in step one is added to the oxidized cellulose dispersion liquid prepared in step two, and is fully stirred to obtain an oxidized cellulose-supported porous MXene microgel material.

[0053] Subsequently, a porous MXene-modified lithium ion battery solid-state electrolyte is prepared, and the specific steps are as follows:

[0054] The cellulose-supported porous MXene microgel 2 prepared above is uniformly coated on the front and back of the lithium battery polymer separator 1, and vacuum dried to obtain a porous MXene-modified lithium ion battery solid-state electrolyte. After drying, the thickness of the MXene coating layer on the front and back of the separator is 10 μm.

[0055] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the application being indicated by the following claims.

Claims

1. A method for preparing a porous MXene-modified solid electrolyte for lithium-ion batteries, characterized in that, The lithium-ion battery solid electrolyte consists of a lithium battery polymer separator and a porous MXene microgel coated thereon; the preparation method includes: Porous MXene microgels were uniformly coated onto both sides of a lithium-ion battery polymer separator and then vacuum dried. The preparation method of the porous MXene microgels is as follows: Step 1: Take MXene nanosheets and stir them into hydrogen peroxide solution. Stir and etch the solution, then centrifuge and wash the solution after the reaction, and ultrasonically disperse it to obtain a porous MXene nanosheet solution. Step 2: Add the cellulose raw material to deionized water, crush and stir to fully disperse and evenly obtain a cellulose dispersion. Step 3: Add the porous MXene nanosheet solution to the cellulose dispersion and stir to obtain cellulose-supported porous MXene microgel; The mass ratio of MXene nanosheets to hydrogen peroxide solution is 0.1–1, and the mass concentration of H2O2 solution is 0.01%–0.1%; the mass ratio of MXene nanosheets to cellulose is 20:1–1:

1. The cellulose dispersion contains 0.5% to 4% cellulose by mass.

2. The preparation method according to claim 1, characterized in that, The lithium battery polymer separator includes one of the following: microporous polyolefin separator mainly composed of polyethylene and polypropylene, PVDF separator, polyimide separator, aramid resin separator, and ceramic separator; The porous MXene microgel is composed of porous MXene nanosheets and cellulose cross-linked together.

3. The preparation method according to claim 2, characterized in that, The lithium battery polymer separator is a microporous polyolefin separator.

4. The preparation method according to claim 1, characterized in that, The MXene nanosheets are Ti3C2T x .

5. The preparation method according to claim 1, characterized in that, The etching temperature is 20–80°C, and the etching time is 10–100 min.

6. The preparation method according to claim 1, characterized in that, The cellulose is selected from one or more of bacterial cellulose, nanocellulose, micro-cellulose, and oxidized cellulose.

7. The preparation method according to claim 1, characterized in that, After drying, the thickness of the porous MXene microgel on both sides of the lithium battery polymer separator is 1–10 μm.

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