Method for dual modification of all-solid-state battery and all-solid-state battery prepared by same
By adding boron-containing compounds to the body and interface layer of the solid electrolyte, the dual modification of boron elements is achieved, and the battery failure problem caused by solid contact between the solid electrolyte and the metal lithium interface is solved, which significantly improves the cycle stability and safety of the battery.
Patent Information
- Application Number
- CN202510258923.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-06
- Publication Date
- 2025-05-27
AI Technical Summary
The solid interface between the solid electrolyte and metal lithium leads to large interface impedance and uneven lithium deposition, which then forms a hybrid conductive interface, promoting the growth of lithium dendrites, resulting in the destruction and failure of the battery structure.
Double modification of boron element is achieved by adding boron-containing compounds to the solid electrolyte body and the interface layer respectively. The low melting point characteristics of the boride allow it to form a glass phase during the sintering process, fill the grain boundaries and disperse the stress, and improve interface stability.
It effectively reduces the interface impedance, prevents lithium dendrites from penetrating, improves the long cycle stability and safety of the battery, and extends the service life of the battery.
Smart Images
Figure CN120040176A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of electrochemistry, and specifically relates to a method for double-modifying all-solid-state batteries and the all-solid-state batteries prepared thereby. Background Art
[0002] The theoretical specific capacity of lithium-ion batteries is 3860 mAh g -1 , and it is considered to be the most promising battery that can meet the requirements of high energy density. However, the serious side reactions between liquid electrolytes (LE) and lithium metal and the formation of lithium dendrites have severely hindered the development and commercial application of lithium-ion batteries. Compared with traditional liquid electrolytes, inorganic solid electrolytes have inherent advantages such as a wide electrochemical window, non-flammability, and high rigidity. Developing solid-state batteries (SSEs) based on lithium (Li) metal anodes is considered to be one of the effective means to solve the safety and long cycle stability of traditional liquid batteries. Solid electrolytes have attracted more and more attention due to their high ionic conductivity at room temperature, good air stability, and low raw material cost.
[0003] However, the solid electrolyte and metallic lithium have a large rigidity, and the solid-solid contact at their interface is a point-to-point contact, resulting in a large interfacial impedance and poor ion transport ability. It will also lead to uneven deposition of lithium, forming a mixed conductive interface (MCI). Its high electronic conductivity will accelerate the growth of lithium dendrites at the grain boundaries inside the solid ceramic electrolyte, resulting in the destruction of the overall structure and the failure of the solid-state battery.
[0004] In order to stabilize the interface between the solid electrolyte and lithium metal, one of the most common methods at present is to introduce an intermediate layer to physically isolate the contact. This strategy has a promoting effect on the long cycle stability of the battery. However, after long-term cycling, the failure of the battery will ultimately occur inside the ceramic. Although the introduction of the intermediate layer avoids the direct contact between the solid electrolyte and the lithium sheet, it cannot modify the inherent defects of the ceramic sheet itself. In fact, studies have shown that in most cases, lithium dendrites deposit at the grain boundaries of the ceramic sheet, causing the ceramic sheet to break, ultimately leading to the failure of the battery performance.
[0005] At present, many researchers have explored intermediate layers, such as atomic layer deposition of ZnO on the surface of solid electrolytes; spraying a layer of BN on the surface; introducing a polymer electrolyte with high electronic insulation on the surface of the electrolyte, etc. However, there is still a lack of exploration of modifying the internal defects of ceramic sheets, which is still a great challenge for the development of long-cycle stable solid-state batteries, and there is an urgent need for a strategy to modify the main body.
[0006] In order to solve the above problems, the present invention is proposed. Summary of the Invention
[0007] In view of the deficiencies in the internal modification and interfacial modification of ceramic electrolytes in the prior art, the present invention provides a method for double modification of all-solid-state batteries based on boron element and the all-solid-state batteries prepared thereby, enabling them to be efficiently applied in the field of high-energy and high-safety lithium metal batteries.
[0008] To achieve this technical objective, the solution of the present invention is as follows:
[0009] The first aspect of the present invention provides a method for double modification of all-solid-state batteries, which includes: using boron-containing compounds to perform boron element modification on the solid electrolyte body and the solid electrolyte interface layer respectively, so that both the solid electrolyte body and the solid electrolyte are added with boron-containing compounds, thereby double-modifying the all-solid-state battery based on boron element, and the melting points of the borides are all lower than the sintering temperature of the solid electrolyte. The boron-containing ceramic electrolyte interface layer and the boron-containing ceramic electrolyte body double-modify the ceramic electrolyte inside and outside.
[0010] Preferably, the method for performing boron element modification on the ceramic electrolyte body using a boron-containing compound includes: adding the boron-containing compound to the solid electrolyte body to obtain a boron-containing solid electrolyte body, thereby completing the modification of the solid electrolyte body.
[0011] The method for performing boron element modification on the solid electrolyte interface layer using a boron-containing compound includes: immersing the solid electrolyte in a solution containing a boron-containing compound, making the solid electrolyte fully contact with the solution containing the boron-containing compound, and forming a boron-containing polymer protective layer on the surface of the solid electrolyte, thereby completing the modification of the solid electrolyte interface layer.
[0012] Preferably, the boron-containing compound includes a boron-containing inorganic compound or a boron-containing organic compound. The boron-containing inorganic compound includes one or more of boron oxide, boric acid, lithium tetraborate, lithium tetrafluoroborate, lithium bis(oxalato)borate, and borax, etc.; the boron-containing organic compound includes one or more of triethyl borate, lithium borohydride, and lithium tetraphenylborate, etc.
[0013] Preferably, the melting point of the boron-containing inorganic compound is lower than 800 °C, and the melting point of the boron-containing organic compound is lower than 200 °C.
[0014] Preferably, the difference between the melting point of the added boron-containing inorganic compound and the sintering temperature of the solid electrolyte does not exceed 300 °C.
[0015] Preferably, the addition amount of the boron-containing inorganic compound in the boron-containing electrolyte body is 2 wt% - 8 wt% of the ceramic electrolyte body, and the addition amount of the boron-containing compound in the boron-containing polymer protective layer is 2 wt% - 4 wt% of the polymer protective layer.
[0016] Preferably, the polymer protective layer added with the boron-containing compound needs to be in a liquid state, and the heating temperature is 60 °C - 100 °C.
[0017] Preferably, the polymer matrix used is succinonitrile, and the content of LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) added is 2-4 wt%.
[0018] Preferably, the soaking time of the solid electrolyte in the polymer protective layer container containing the boron-containing polymer is 1-5 minutes.
[0019] Preferably, the ceramic electrolyte is an inorganic ceramic electrolyte.
[0020] Preferably, the doubly modified all-solid-state battery is used to improve the interfacial stability between the positive and negative electrodes and prevent the failure of lithium dendrite penetration and short circuit.
[0021] In the second aspect of the present invention, a lithium-ion battery is provided, and the ceramic electrolyte body and the ceramic electrolyte interface layer are a boron-containing ceramic electrolyte body and a boron-containing polymer protective layer obtained by the method of the doubly modified all-solid-state battery based on boron element described in the first aspect of the present invention.
[0022] Compared with the prior art, the present invention has the following beneficial effects:
[0023] 1. In the method of the doubly modified all-solid-state battery provided by the present invention, on the one hand, a simple means of grain boundary regulation is utilized. The added boron-containing inorganic compound turns into a glass phase during the sintering process of the solid electrolyte to fill the grain boundaries. The glass phase wraps the ceramic particles, which can protect the ceramic particles from the impact of electrons, and at the same time, the surface charge distribution is significantly homogenized, which is helpful for the interfacial stability. On the other hand, the added boron-containing compound turns into a glass phase to fill the grain boundaries, which can effectively disperse stress and greatly improve the crack growth resistance. On the third hand, the added boron-containing polymer protective layer can effectively wet the positive electrode sheet, release more capacity, and at the same time avoid the solid-solid contact between the solid electrolyte and the lithium sheet, reducing the interfacial resistance. The method of the doubly modified all-solid-state battery based on boron element provided by the present invention promotes the long-cycle stability of the all-solid-state battery through internal and external modifications.
[0024] 2. In the method of the doubly modified all-solid-state battery provided by the present invention, the polymer protective layer can isolate the electron transfer, effectively reduce the side reaction with the lithium sheet, inhibit the diameter growth at the interface, and promote the long-cycle stability of the battery.
[0025] 3. In the method of the doubly modified all-solid-state battery provided by the present invention, the modification of the ceramic electrolyte body and the modification of the ceramic electrolyte interface layer have a synergistic and progressive relationship, and a same protective bond will be formed. During the cycling process of the all-solid-state battery, the two can achieve bonding at the molecular or even atomic level, which can greatly improve the stability of the chemical bond and has a good promoting effect on the whole battery.
[0026] Description of the drawings.
[0027] Figure 1 The modified B provided in Embodiment 1 of the present invention 6 CT image of the unmodified LATP lithium symmetric battery before cycling.
[0028] Figure 2 The modified B provided in Embodiment 1 of the present invention 6 CT image of the modified B-LATP lithium symmetric battery after 50 h of cycling.
[0029] Figure 3 CT image of the unmodified LATP lithium symmetric battery before cycling provided in Embodiment 1 of the present invention
[0030] Figure 4 CT image of the unmodified LATP lithium symmetric battery after 50 h of cycling provided in Embodiment 1 of the present invention
[0031] Figure 5 It is the test chart of the limiting current density of the unmodified LATP provided in Embodiment 1 of the present invention.
[0032] Figure 6 It is the modified B provided in Embodiment 1 of the present invention 6 -LATP limiting current density test chart.
[0033] Figure 7 It is the battery capacity chart of the unmodified Li / SN / LATP / SN / LFP full battery provided in Embodiment 2 of the present invention at 0.2C.
[0034] Figure 8 It is the modified Li / SN-B provided in Embodiment 2 of the present invention 6 -LATP-SN / LFP full battery capacity chart at 0.2C.
[0035] Detailed implementation manners.
[0036] The present invention will be further described below through embodiments, which are not limited to this embodiment only. For the experimental methods without specific conditions noted in the embodiments, they are usually carried out according to the conventional conditions and the conditions described in the manuals, or according to the conditions recommended by the manufacturers. For general equipment, materials, reagents, etc., they can be obtained from commercial channels without special instructions.
[0037] Embodiment 1
[0038] A method for double-modifying all-solid-state batteries, wherein the modified ceramic electrolyte is NASICON-type Li superionic conductor Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3(Lithium aluminum titanium phosphate) ceramic sheet, the boron-containing compound added to the ceramic electrolyte body is boron oxide (B 2 O 3 ), the negative electrode is metallic lithium, and the polymer protective layer is a polymer matrix (succinonitrile SN) plus an appropriate amount of boron-containing compound (lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium difluoro(oxalato)borate (LiDFOB). The preparation and assembly of the battery electrode materials are carried out in an inert atmosphere (argon). The addition amount of the boron-containing compound in the boron-containing ceramic electrolyte body is 6 wt% of the ceramic electrolyte body, and the addition amount of the boron-containing compound in the boron-containing polymer protective layer is 3 wt% of the polymer matrix.
[0039] Step (1), first prepare a modified inorganic ceramic electrolyte. Weigh the required raw materials lithium carbonate, boron oxide, ammonium dihydrogen phosphate, aluminum oxide and titanium dioxide according to the chemical stoichiometry of LATP. Then, through ball milling, drying, and sieving, we obtain the raw material powder. Then, pre-calcine at 500 °C. After mixing evenly, manually grind the calcined precursor. After it becomes powdery, sieve it, then carry out ball milling, drying, and sieving again to obtain a powder with uniform particles. Put the obtained powder into a mold and form it under isostatic pressure of 200 MPa. The pressure holding time is 120 min to prepare an electrolyte wafer with a diameter of 11 mm and a thickness of 1.6 mm. Then, carry out secondary sintering of the obtained electrolyte wafer at 700 °C to obtain a solid electrolyte wafer with a diameter of 9 mm and a thickness of 1.5 mm.
[0040] Step (2), then modify the boron element on the interface layer of the ceramic electrolyte. Polish and smooth the ceramic sheet. Assemble the battery in a glove box and heat it to 80 °C to make the polymer protective layer into a liquid state. Then, immerse the ceramic sheet in it for 2 min. Press the cut lithium sheet (diameter 8 mm, thickness 300 μm) on both sides of the protective layer and let it stand for five minutes to obtain Li / SN / LATP / SN / Li.
[0041] For comparison, in this example, an unmodified LATP ceramic electrolyte was prepared. Here, unmodified means that boron oxide was not added during the preparation process of the LATP ceramic electrolyte body in step (1), boron element modification was not carried out, and the step of modifying the boron element on the interface layer of the ceramic electrolyte in step (2) was not carried out. Specifically, Figure 1 is the CT diagram of B 6 -LATP before assembling the symmetric battery and cycling, Figure 2 is the CT diagram of the symmetric battery B 6 -LATP after 50 h of cycling, Figure 3 is the CT diagram of LATP before assembling the symmetric battery and cycling, Figure 2 is the CT diagram of the symmetric battery LATP after 50 h of cycling. Obviously, before cycling, the boron element bulk modification of B 6- There is no difference in the CT images of LATP and unmodified LATP. However, after 50 hours of cycling, it is obvious that the unmodified LATP battery has cracked, while B 6 - LATP remains intact. Figure 5 This is the test of the limiting current density of unmodified LATP, which reaches 0.4 mA / cm 2 , Figure 6 This is the test of the limiting current density of modified B6-LATP, which reaches 0.8 mA / cm 2 .
[0042] Example 2.
[0043] A method for a dual-modified all-solid-state battery, wherein the ceramic electrolyte prepared by modification is a NASICON-type Li superionic conductor Li 1.3 Al 0.3 Ge 1.7 (PO 4 ) 3 (lithium aluminum germanium phosphate) ceramic sheet. The boron-containing compound added to the ceramic electrolyte body is lithium tetraborate. The negative electrode is metallic lithium, and the polymer protective layer is a polymer matrix (succinonitrile) plus an appropriate amount of boron-containing compounds (lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium bis(oxalato)borate (LiBOB)). The preparation and assembly of the battery electrode materials are carried out in an inert atmosphere (argon). The addition amount of the boron-containing compound in the boron-containing ceramic electrolyte body is 6 wt% of the ceramic electrolyte body, and the addition amount of the boron-containing compound in the boron-containing polymer protective layer is 2 wt% of the polymer matrix.
[0044] Step (1), first prepare the inorganic ceramic electrolyte modified in the body. Weigh the required raw materials lithium carbonate, lithium tetraborate, ammonium dihydrogen phosphate, aluminum oxide and germanium dioxide according to the chemical stoichiometry of LAGP. Then, after ball milling, drying and sieving, obtain the raw material powder. Then, perform pre-sintering at 600 °C. After mixing evenly, manually grind the calcined precursor. After it becomes powdery, perform sieving treatment, then carry out ball milling, drying and sieving to obtain a uniformly granulated powder. Put the obtained powder into a mold and form it under isostatic pressure of 200 MPa. The pressure holding time is 120 min to prepare an electrolyte wafer with a diameter of 11 mm and a thickness of 1.6 mm. Then, perform secondary sintering of the obtained electrolyte wafer at 800 °C to obtain a solid electrolyte wafer with a diameter of 9 mm and a thickness of 1.5 mm.
[0045] Step (2), then modify the boron element on the interface layer of the ceramic electrolyte. Polish and smooth the ceramic sheet. Assemble the battery in a glove box, heat it to 80 °C to make the polymer protective layer into a liquid state, then immerse the ceramic sheet in it for 1 - 3 min. Press the cut lithium sheet (diameter 8 mm, thickness 300 μm) on one side of the protective layer, and the cut positive electrode sheet (LFP, 2 mg cm-2 ) Let it stand for five minutes to obtain Li / SN-B 6 -LAGP-SN / LFP.
[0046] For comparison, an unmodified LAGP ceramic electrolyte was prepared in this example. Here, "unmodified" means that lithium tetraborate was not added during the preparation of the LAGP ceramic electrolyte body in step (1), boron element modification was not carried out, and the step of boron element modification of the ceramic electrolyte interface layer in step (2) was not carried out.
Claims
1. A method for double-modified all-solid-state battery, characterized in that: It includes: The solid electrolyte body and the solid electrolyte interface layer are respectively modified with boron by using boron-containing compounds, so that both the solid electrolyte body and the solid electrolyte interface layer are added with boron-containing compounds, thereby doubly modifying the all-solid-state battery based on the boron element, and the melting points of the borides are lower than the sintering temperature of the solid electrolyte.
2. The method for double-modified all-solid-state battery according to claim 1, characterized in that: The method of modifying the solid electrolyte body with boron by using a boron-containing compound comprises: adding the boron-containing compound to the solid electrolyte body to obtain the boron-containing solid electrolyte body, thereby completing the modification of the solid electrolyte body. The method of modifying the solid electrolyte interface layer with boron by using a boron-containing compound comprises: immersing the solid electrolyte in a solution containing the added boron-containing compound, so that the solid electrolyte is fully in contact with the solution containing the added boron-containing compound, forming a boron-containing polymer protective layer on the surface of the solid electrolyte, thereby completing the modification of the solid electrolyte interface layer.
3. The method for double-modified all-solid-state battery according to claim 2, characterized in that: The boron-containing compound includes a boron-containing inorganic compound or a boron-containing organic compound. The boron-containing inorganic compound includes one or more of boron oxide, boric acid, lithium tetraborate, lithium tetrafluoroborate, lithium bis(oxalatoborate) and borax; the boron-containing organic compound includes one or more of triethyl borate, lithium borohydride and lithium tetraphenylborate.
4. The method for double-modified all-solid-state battery according to claim 3, characterized in that: The boron-containing inorganic compound has a melting point lower than 800°C, and the boron-containing organic compound has a melting point lower than 200°C.
5. The method for double-modified all-solid-state battery according to claim 2, characterized in that: The difference between the melting point of the added boron-containing inorganic compound and the sintering temperature of the solid electrolyte cannot exceed 300°C.
6. The method for double-modified all-solid-state battery according to claim 2, characterized in that: The amount of the boron-containing inorganic compound added to the boron-containing electrolyte body is 2wt%-8wt% of the ceramic electrolyte body, and the amount of the boron-containing compound added to the boron-containing polymer protective layer is 2wt%-4wt% of the polymer protective layer.
7. The method for double-modified all-solid-state battery according to claim 2, characterized in that: The polymer protective layer to which the boron-containing compound is added needs to be in liquid state, and the heating temperature is 60°C-100°C.
8. The method for double-modified all-solid-state battery according to claim 7, characterized in that: The polymer matrix used is succinonitrile, and the added LiTFSI (lithium bistrifluoromethanesulfonyl imide) content is 2-4wt%.
9. An all-solid-state battery, characterized in that: The ceramic electrolyte body and the ceramic electrolyte interface layer are a boron-containing ceramic electrolyte and a boron-containing polymer protective layer prepared by the method for the double-modified all-solid-state battery according to any one of claims 1 to 11.