Preparation method of Zr-based halide electrolyte with high ionic conductivity

Abstract

The invention discloses a preparation method of a Zr-based halide electrolyte with high ionic conductivity, and belongs to the technical field of solid electrolyte preparation. According to the technical scheme, LiCl, ZrCl4, CuCl2 and Li2O are mixed and then subjected to high-speed ball milling, and the Zr-based halide electrolyte Li2. 1Zr0. 95Cu0. 05Cl4. 4O0. 8 with the high ionic conductivity is obtained, the ionic conductivity of the Zr-based halide electrolyte is as high as 2 * 10 <-3 > S cm <-1 >, and the Zr-based halide electrolyte has excellent rate capability and long cycle stability when being applied to a solid-state battery. The preparation method is simple, and the product has excellent performance and great market application potential.

Description

Technical Field

[0001] The invention belongs to the technical field of solid electrolyte preparation, and specifically relates to a method for preparing a Zr-based halide electrolyte with high ionic conductivity. Background Art

[0002] All-solid-state lithium batteries have the advantages of better safety, higher energy density and environmental friendliness, and are strong candidates for the next generation of lithium batteries. Among them, solid electrolytes are the key to solid-state batteries. Solid electrolytes can be divided into polymer type, oxide type, sulfide type and halide type. In general, polymers and oxides are called semi-solid electrolytes because a trace amount of electrolyte needs to be added to wet the interface when assembling the battery. The electrochemical window of sulfide electrolytes is about 0.6-2.5V. When matching ternary cathode materials, serious side reactions will occur at the interface, causing the battery to fail rapidly during the cycle. Halide electrolytes have the advantages of wide electrochemical window and high ionic conductivity, and are favored by researchers. In the halide electrolyte family, Li2ZrCl6 (LZC) has the characteristics of simple preparation process, low cost, wide electrochemical window and good compatibility with high-voltage cathode materials, so it is very promising for use in all-solid-state lithium batteries. However, the ionic conductivity of LZC is low, only (0.4×10 -3 S cm -1 ), which cannot meet the requirements of all-solid-state batteries for Li + Transmission capacity requirements. Summary of the invention

[0003] The purpose of the present invention is to provide a method for preparing a Zr-based halide electrolyte with high ionic conductivity, so as to effectively solve the problem of low ionic conductivity of LZC.

[0004] To achieve the above object, the present invention adopts the following technical solution:

[0005] A method for preparing a Zr-based halide electrolyte with high ionic conductivity: After mixing LiCl, ZrCl4, CuCl2 and Li2O, firstly perform low-speed ball milling at a rotation speed of 100 rpm to ensure that all precursors are fully mixed, and then perform high-speed ball milling at a rotation speed of 600 rpm for 10 hours to obtain the Zr-based halide electrolyte with high ionic conductivity Li 2.1 Zr 0.95 Cu 0.05 Cl 4.4 O 0.8 .

[0006] All procedures were performed in an argon-filled environment with H2O and O2 concentrations less than 0.1 ppm.

[0007] The beneficial effects of the present invention are: the present invention uses anion and cation engineering (Cu2+ / O 2- ) strategy to construct halide superionic conductors in a coordinated manner and to regulate them in LZC structures (O 2- / Cl - ) ratio, LZC was transformed from crystalline phase to amorphous phase to obtain Li 2.1 Zr 0.95 Cu 0.05 Cl 4.4 O 0.8 (LZCCO 0.8 ) halide superionic conductor. 2+ / O 2- ) modified LZC electrolyte increases from 0.4×10 -3 S cm -1 Increase to (2×10 -3 S cm -1 ). It is applied to solid-state batteries for assembly, which have excellent rate performance and long cycle stability, and also reflects the LZCCO 0.8 Halide electrolytes have great market application potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 (a) LZC, LZCC and Li 2.1 Zr 0.95 Cu 0.05 Cl x O y (LZCCO y , x+2y=2.1,y=0.4,0.6,0.8,1.0) XRD diffraction pattern of electrolyte, the magnified area is a-129-35°; (b) Quantitative analysis of LZC, LZCC, and LZCO using LiF as the internal standard sample 0.8 and LZCCO 0.8 Amorphous content in electrolyte; (cd) LZC, LZCC and LZCCO y Arrhenius plot and summary of ionic conductivity of electrolytes; (e) LZCCO 0.8 ,LZCCO 1.0 and LiCl 7 Li SSNMR spectrum.

[0009] Figure 2 s-NCM83|LZC or LZCCO 0.8 -Electrochemical performance of all-solid-state lithium batteries assembled with Li6PS5Cl|Li-In: (a) charge and discharge curves at 0.1C; (b) rate performance in the range of 0.2 to 2C; (c) long-term cycle performance at 1C; the voltage range of the above tests is 2.8V-4.3V. DETAILED DESCRIPTION

[0010] In order to make the contents of the present invention easier to understand, the technical solution of the present invention is further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0011] Experimental steps: for the synthesis of Li2ZrCl6 and Li 2.1 Zr 0.95 Cu 0.05 Cl x O y (where x+2y=2.1,y=0.4,0.6,0.8,1.0) The electrolyte was prepared by high-energy ball milling of LiCl, ZrCl4, CuCl2 and Li2O in a certain stoichiometric ratio. Low-speed ball milling was first performed at 100 rpm to ensure that all precursors were fully mixed, and then high-speed ball milling was performed at 600 rpm for 10 h. All procedures were performed in a glove box filled with argon (H2O, O2<0.1 ppm).

[0012] Battery assembly steps: using LZC or LZCCO 0.8 Electrolyte, Li6PS5Cl electrolyte, LiNi 0.83 Co 0.11 Mn 0.06 O2 (NCM83) and Li-In negative electrode were used to assemble all-solid-state lithium batteries. NCM83 and halide electrolyte were mixed in a mass ratio of 70:30, and the mixture was manually ground in a mortar for 10 minutes to obtain a positive electrode composite powder. 60 mg LZC or LZCCO 0.8 The electrolyte powder was placed in a PEEK cylinder (10 mm in diameter) and pressed at 120 MPa for 1 minute. Then, 7-9 mg of composite cathode powder was added to one side of the halide electrolyte and pressed at 360 MPa for 3 minutes. In order to improve the reduction stability at the interface between the halide electrolyte and the negative electrode, 40 mg of Li6PS5Cl powder was evenly dispersed on one side of the Li-In alloy and pressed at 120 MPa for 1 minute. Finally, a piece of In foil (0.1 mm in thickness and 10 mm in diameter) was placed on the surface of Li6PS5Cl. A lithium foil (0.05 mm in thickness and 8 mm in diameter) was then placed on the In foil. The assembled battery was placed in a custom stainless steel housing. All preparation processes were carried out in an argon-filled glove box (H2O, O2 <0.1 ppm). The LAND battery test system was used to test Li / Li at 2.8-4.3 V. + Long cycle testing of all-solid-state lithium batteries was carried out within a voltage range of 200 MHz.

[0013] like Figure 1As shown in Figure 2, LZC was synthesized by high-energy ball milling. The XRD pattern of LZC corresponds to a trigonal phase with a hexagonal close-packed structure (hcp). 2+ / O 2- ) was introduced into the cost-effective LZC, and highly amorphous LZCCO was obtained using a typical high-energy ball milling method. 0.8 At the same time, the corresponding Li 2.1 Zr 0.95 Cu 0.05 Cl6(LZCC) and Li2ZrCl 4.4 O 0.8 (LZCO 0.8 ). In LZC, high electronegativity Cu 2+ Zr 4+ The obtained diffraction peaks also correspond to the trigonal crystal phase, indicating that Cu 2+ and Zr 4+ The ionic radius of Cu 2+ Replace Zr 4+ The phase or crystal structure will not be changed. Compared with the characteristic peaks of LZC, the characteristic peak intensity of LZCC is reduced and the diffraction peak is broader. This phenomenon indicates that Cu 2+ Doping may increase the amorphous fraction during mechanochemical synthesis. To further increase the amorphous fraction in LZCC, Li2O was used to replace part of LiCl. By keeping the total lithium ion molar ratio unchanged (Li: 2.1 mol), we systematically introduced O 2- Replace Cl - , adjusting the amorphization degree of LZCC and studying its relationship with ion transport. A series of LZCCO y As shown in Figure b, LZCCO 0.8 The amorphous component ratio of LZCCO is the highest, reaching 80.6%. Importantly, the ionic conductivity and activation energy of LZCCO were measured to verify that 0.8 The amorphous content in the sample is dominant, and its ionic conductivity is 2.05×10 -3 S cm -1 , the activation energy is 0.287eV, which is significantly better than other samples. 0.8 It exhibits a low electronic conductivity of about 5.6×10 -9 Scm -1 In addition, LZCCO 0.8 and LZCCO 1.0 Conducted 7 Li solid-state nuclear magnetic resonance (SSNMR) measurements ( Figure 1 e) Analysis of the lithium chemical environment further demonstrated that Li + The transmission of LZCCO is dominant. LiCl is used as the chemical shift reference (δ = -0.66ppm). The full width at half maximum (FWHM) of peak 1 is 0.8 0.55 in LZCCO 1.0 The average is 0.77. 0.8 The FWHM of peak 1 is significantly lower than that of LZCCO 1.0 , further indicating faster lithium transfer kinetics. These findings indicate that the introduction of a certain amount of Li2O can help improve LZCCO y The lithium conductivity in the electrolyte and the activation energy are reduced.

[0014] Thanks to LZCCO 0.8 The electrolyte has strong reducibility, and Li6PS5Cl is used to avoid Li-In negative electrode and LZCCO 0.8 Direct contact with electrolyte. s-NCM83|LZC or LZCCO 0.8 -Li6PS5Cl|Li-In were used to assemble all-solid-state lithium batteries and evaluate their electrochemical performance. Figure 2 As shown, using LZCCO 0.8 The all-solid-state battery assembled with electrolyte exhibits excellent rate performance. 0.8 The rate performance of the battery is 188.1, 161.1, 136.3 and 106.3 mAh g at 0.2C, 0.5C, 1C and 2C, respectively. -1 The high reversible capacity of LZCCO exceeds the rate performance of LZC. When the rate increases from 0.5C to 1C and then from 1C to 2C, the capacity drop is within an acceptable range. Even at 2C, LZCCO 0.8 The battery still retains 106.3mAh g -1 The capacity is significantly higher than LZC’s 57.1mAh g -1 The difference in capacity can be attributed to LZCCO 0.8 The fast lithium ion migration capability of LZC and LZCCO indicates that the ion transport kinetics significantly affects the rate capability of solid-state batteries. 0.8 The capacity difference between them becomes more obvious. 0.8 It shows smaller polarization and still maintains 127.4 mAh g after 400 cycles at 1C. -1 The discharge capacity of LZC was 66.1 mAh g -1This difference can be attributed to the low lithium ion conductivity of LZC, which hinders the rapid migration of lithium ions. In summary, the present invention explores a convenient, low-cost, and optimal preparation scheme for mass production of halide electrolyte materials. The method is simple and efficient, has good reproducibility, and excellent material properties.

[0015] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for preparing a high ionic conductivity Zr-based halide electrolyte, characterized in that: After LiCl, ZrCl4, CuCl2 and Li2O were mixed, they were firstly subjected to low-speed ball milling at a rotation speed of 100 rpm to ensure that all precursors were fully mixed, and then subjected to high-speed ball milling at a rotation speed of 600 rpm for 10 h to obtain the high ionic conductivity Zr-based halide electrolyte Li 2.1 Zr 0.95 Cu 0.05 Cl 4.4 O 0.8 .

2. The method according to claim 1, characterized in that: All procedures were performed in an argon-filled environment with H2O and O2 concentrations less than 0.1 ppm.

3. A Zr-based halide electrolyte with high ionic conductivity prepared by the method according to claim 1 or 2.

4. A high ionic conductivity Zr-based halide electrolyte prepared by the method according to claim 1 or 2 is applied to an all-solid-state lithium battery.

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