Application of trace diluent type high-nuclear inorganic salt in electrolyte

Abstract

The invention belongs to the field of preparation of energy storage materials, and particularly relates to application of a trace diluent type high-nuclear inorganic salt in an electrolyte. The method comprises the following specific steps: dissolving a zinc salt in water to prepare a blank electrolyte, dispersing a high-core inorganic salt in the solution, standing and filtering to prepare the electrolyte, and the method can adapt to different battery systems by changing the concentration of the zinc salt solution and the content of the high-core inorganic salt. The high-nuclear inorganic salt provided by the invention has the effect of a diluent, and a zinc ion solvation structure and a hydrogen bond network of free water are effectively adjusted through the steric hindrance effect of a large-size anion cluster. The technical scheme provided by the invention is simple in operation process, low in cost and high in safety, and the prepared electrolyte can remarkably improve the normal-temperature and low-temperature cycle performance and stability of the battery.

Description

Technical Field

[0001] The invention belongs to the field of energy storage material preparation, and in particular relates to the application of a trace diluent type high-nuclear inorganic salt in an electrolyte. Background Art

[0002] With the increasing prominence of energy and environmental issues, the effective utilization and rational distribution of green and sustainable energy face huge challenges, which has promoted the development of low-cost, high-safety electrochemical energy storage systems. Since its commercialization in the last century, lithium-ion batteries (hereinafter referred to as LIBs) have dominated the field of electrochemical energy storage due to their high energy density and cycle stability. However, LIBs have problems such as high cost and great environmental hazards, which further limit their application. Compared with organic lithium-ion batteries, aqueous batteries have broad application prospects due to their advantages such as low cost, high safety, and high ionic conductivity. Among them, aqueous zinc-ion batteries (hereinafter referred to as AZIBs) have low redox potential (-0.76 V vs. SHE), high theoretical specific capacity (820 mAh·g -1 ), environmentally friendly, and easy to assemble, making it one of the competitive alternatives to LIBs.

[0003] However, AZIBs still have many shortcomings, including the existence of dendrites, dead zinc, and side reactions (corrosion, hydrogen evolution) in the zinc negative electrode, which lead to low coulombic efficiency and poor cycle stability, seriously hindering their practical application.

[0004] To address the above problems, it is proposed to improve the liquid electrolyte system by using high concentration electrolytes (HCEs) to reconstruct Zn 2+ The solvation shell of HCEs and the destruction of the hydrogen bond (HB) network between water molecules improve the electrochemical stability. However, HCEs inevitably increase the viscosity of the liquid electrolyte and sacrifice the wettability of the electrolyte-electrode interface, especially at low temperature conditions, which has a great impact on the stability of the battery. In addition, the increase in salt usage leads to increased costs, which significantly limits the practical application feasibility of HCEs. As a sublimation of the HCEs strategy, local high concentration electrolytes (LHCEs) avoid the inherent problems brought by high salt concentration by introducing weakly coordinated or non-coordinating diluents combined with low-concentration electrolytes, thereby achieving the optimization goal of the electrolyte. However, current research mainly focuses on organic diluents, which have potential safety hazards. High dosage will also significantly increase the cost of the electrolyte, and organic diluents and Zn 2+ The strong binding ability leads to high desolvation energy barrier and poor low-temperature performance. Therefore, the exploration of low-dosage, high-safety, and high-performance diluents still faces huge challenges.

[0005] At present, high-nuclear inorganic salts are mainly used as electrolyte additives, which have the advantage of being able to significantly change the electrolyte solvation structure at a low addition amount, but their application as diluents through physical effects (electrostatic interactions) is still non-existent. For example, Chen et al. used Nd9Si4W 39 Polyacid as electrolyte additive, Nd9Si4W 39 The structure of polyacid changes from SiW9O to 34 Transformed into SiW 10 O 37 Although a protective layer is formed on the surface of the zinc anode, it has little effect on improving the electrolyte solvation structure, resulting in poor low-temperature performance of the battery (Y. Chen, ZX Zhang, PW Cai, et al. Polyoxotungstate Featuring Zinc-Ion-Triggered Structural Transformation as An Efficient Electrolyte Additivefor Aqueous Zinc-Ion Batteries. Angew. Chem. Int. Ed. 2025, 64, e202420284). Therefore, there is an urgent need for a low-dosage, highly safe, high-performance diluent-like high-nuclear inorganic salt to achieve excellent cycle life and stability at both room and low temperatures. Summary of the Invention

[0006] The present invention addresses the problems of large organic diluent usage, potential safety hazards, and poor low-temperature performance in the prior art, and provides a method for applying a trace diluent-type high-nuclear inorganic salt in an electrolyte. The specific steps are: dissolving a zinc salt in water to prepare a blank electrolyte, dissolving a high-nuclear inorganic salt in the blank electrolyte, and filtering the blank electrolyte after standing. The present invention can further adapt to different battery systems by changing the concentration of the zinc salt solution and the content of the high-nuclear inorganic salt, such as achieving better low-temperature performance in low-temperature resistant electrolytes such as zinc sulfate; and achieving high power and long cycle performance in a fluorine-rich protective layer electrolyte of zinc trifluoromethanesulfonate. The trace diluent-type high-nuclear inorganic salt proposed in the present invention has the advantages of simple operation process and low cost, and the prepared electrolyte can significantly improve the normal temperature and low temperature cycle performance and stability of the battery.

[0007] The Keggin-type phosphotungstate provided by the present invention has the advantages of stable structure, easy acquisition and low cost, and can repel anions from entering the ZnO2-containing phosphotungstate through electrostatic repulsion. 2+The primary solvation shell effectively improves the electrolyte solvation structure, disrupts the hydrogen bond network, reduces the desolvation energy, and achieves excellent room-temperature and low-temperature performance. Therefore, the high-nuclearity inorganic salt provided by the present invention is a trace additive that acts similarly to an inert diluent. The functional feasibility of this diluent-type polyoxometalate material provides important guidance for molecular innovation in polyoxometalate chemistry and its practical application in AZIBs.

[0008] The technical ideas of the present invention are as follows: The significant steric hindrance effect of large molecules can effectively hinder the interaction with Zn 2+ coordination effect, and has abundant hydrogen bonding sites, which can meet the regulation of Zn 2+ Diluent requirements for the solvation shell and hydrogen bond (HB) network. Water-soluble high-core inorganic salts have abundant hydrogen bond acceptors and adjustable molecular size, which can weaken the Zn 2+ The coordination effect of [PW] in the Keggin-type phosphotungstate selected in the present invention can be used to block free water molecules, thereby constructing zinc-based LHCEs to achieve electrolyte optimization, thereby improving the cycle stability of AZIBs, which is of great significance and value for the design of high-performance AZIBs. 12 O 40 ] 3- Polyoxyanions are excluded from Zn 2+ outside the primary solvation shell (PSS) and repel the anions of the zinc salt (such as SO4 2- 、Cl - 、(CF3SO3) - 、ClO4 - 、CH3COO - ), forcing more anions of zinc salts to enter Zn 2+ PSS, and [PW 12 O 40 ] 3- The abundant hydrogen bond acceptors in the material effectively destroy the HB network between water molecules, thereby enhancing the low temperature tolerance.

[0009] The present invention provides an application of a trace diluent-type high-nuclear inorganic salt in an electrolyte, and the specific steps are as follows: S1. Dissolve the zinc salt in deionized water and stir thoroughly to dissolve it to obtain a blank electrolyte; S2. The diluent-type high-nuclear inorganic salt is dispersed in the blank electrolyte prepared in S1, stirred and dissolved, and filtered to obtain an electrolyte; The diluent-type high-nuclear inorganic salt is a Keggin-type phosphotungstate.

[0010] Preferably, the diluent-type high-nuclear inorganic salt is selected from a mixture of one or more of ammonium phosphotungstate, potassium phosphotungstate, sodium phosphotungstate, and magnesium phosphotungstate.

[0011] Preferably, the zinc salt in S1 is a mixture of one or more of zinc sulfate, zinc chloride, zinc trifluoromethanesulfonate, zinc perchlorate, and zinc acetate.

[0012] Preferably, the concentration of the zinc salt in S1 is 1-5 mol / L, the stirring rate is 400-1000 rpm, and the stirring time is 0.5-5 h. The stirring time is determined according to the type and concentration of the zinc salt to ensure the uniformity of the electrolyte.

[0013] Preferably, the diluent-type high-nuclear inorganic salt in S2 accounts for 0.01-5 wt% of the total mass of the blank electrolyte, and the higher the proportion of the diluent-type high-nuclear inorganic salt, the longer the stirring time, the stirring rate is 400-1200 rpm, and the stirring time is 5-18 h.

[0014] Preferably, the stirred and dissolved electrolyte is allowed to stand at room temperature for 10 to 40 minutes before filtering in S2 to ensure the sedimentation of impurities.

[0015] Preferably, the filtration accuracy in S2 is 0.22 μm.

[0016] Preferably, after obtaining the electrolyte in S2, a button battery is assembled using a metal zinc sheet as the negative electrode and filter paper as the separator.

[0017] In the above process, taking Zn(CF3SO3)2 as an example, the [PW 12 O 40 ] 3- Polyoxyanions are excluded from Zn 2+ outside the primary solvation shell (PSS) and repels CF3SO3 through electrostatic repulsion. - , thereby forcing more CF3SO3 - Enter Zn 2+ PSS, due to Zn 2+ Can coordinate with 6 H2O, CF3SO3 - Entering PSS can reduce the [Zn(H2O)6] 2+ The content of [PW 12 O 40 ] 3- The abundant hydrogen bond receptors in Zn effectively destroy the hydrogen bond network between water molecules and inhibit the activity of water molecules. 2+ Solvation shell and high-core inorganic salts help activate more CF3SO3 - , forming a fluorine-rich hybrid solid electrolyte interface (SEI) at the zinc-electrolyte interface, thereby reducing the desolvation kinetic barrier and guiding the Zn2+ Along Zn (002) When using other zinc salts, [PW 12 O 40 ] 3- Polyoxygen anions can also promote more zinc salt anions to enter Zn through electrostatic repulsion. 2+ PSS, reducing the [Zn(H2O)6] 2+ content to optimize battery performance.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) Compared with traditional organic diluents, such as 400% volume addition of tetrahydrofuran (D. Wang, H. Peng,S. Zhang, H. Liu, N. Wang, J. Yang. Localized Anion-Cation Aggregated Aqueous Electrolytes with Accelerated Kinetics for Low-Temperature Zinc Metal Batteries. Angewandte Chemie International Edition, 2023, 62(50) :e202315834.), 60% volume addition of diethylene glycol dimethyl ether (R. Zhang, WK Pang, J. Vongsvivut, JA Yuwono, G. Li, Y. Lyu, Y. Fan, Y. Zhao, S. Zhang, J. Mao, Q. Cai, S. Liu,Z. Guo. Weakly solvating aqueous-based electrolyte facilitated by a soft co-solvent for extreme temperature operations of zinc-ion batteries. Energy &Environmental Science, 2024, 17(13): 4569-81.), 900% volume added poly (1,3-dioxolane) (M. Xi, Z. Liu, Z. Qi, Y. Huang, W. Wang, J. Ding, Z. Tan, H. Liu. Electrolyte for Zn metal battery under extreme temperature operations designby Lewis acid-base chemically mediated polymerization of cyclic ether. EnergyStorage Materials, 2025, 75: 104091.), the diluent-type high-nuclear inorganic salt proposed in the present invention has a low addition amount (mass fraction 0.01~5%) and has better safety, [PW 12 O 40 ] 3- With abundant hydrogen bond acceptors and large molecular size, it can weaken Zn 2+The coordination effect of organic diluents can block free water molecules, thereby constructing a zinc-based local high-concentration electrolyte. Only a very small amount of them needs to be added to have excellent performance, avoiding the inherent problems brought by traditional organic diluents, achieving the optimization goal of the electrolyte, and having the advantages of saving resources, reducing costs, and being environmentally friendly and safe.

[0019] (2) Compared with other tungsten-containing polyoxometalates, the diluent-type high-nuclear inorganic salt proposed in the present invention is a Keggin-type phosphotungstate, which has good solubility and non-flammability. Although it is added to the electrolyte as an additive, it acts as a diluent (not directly participating in the reaction). Although [PW 12 O 40 ] 3- It has abundant coordination sites, and Zn 2+ With [PW 12 O 40 ] 3- There is electrostatic attraction between them, but the large size of the anion cluster has a steric hindrance effect, which makes it impossible to 2+ Coordination, [PW 12 O 40 ] 3- The electrostatic repulsion between zinc salt anions forces more zinc salt anions to enter the Zn 2+ The PSS of Zn 2+ hydrolysis and reduce the desolvation barrier. [PW 12 O 40 ] 3- It has excellent hydrophilicity and can interact with H2O to weaken the hydrogen bond interaction between water molecules. 12 O 40 ] 3- Unable to interact with Zn 2+ Coordination, [PW 12 O 40 ] 3- Clusters still appear in Zn 2+ The outer solvation shell (OSS) of Zn 2+ The adjacent water molecules of PSS and OSS will be preferentially and inevitably captured, reducing the [Zn(H2O)6] 2+ The formation of Zn 2+ The solvation structure forms a locally high-concentration electrolyte with better stability and low-temperature tolerance.

[0020] The high-nuclear inorganic salt additive proposed in the present invention is similar to an efficient diluent, achieving fast kinetics and excellent cyclic stability, and is conducive to the development of AZIBs with excellent performance, safety and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a combustion test of the electrolyte prepared in Example 1, where the left picture is just after ignition, and the right picture is 10 seconds after ignition; Figure 2 The solvation structure diagram of the electrolyte prepared in Example 1 and Comparative Example 1, wherein: Figure 2 a is a schematic diagram of PSS in electrolyte, Figure 2 b is various Zn 2+ Solvation structure distribution, Figure 2 c is the Raman spectrum of -SO3 stretching mode in the electrolyte, in which 2 MZn (OTf) 2 represents Comparative Example 1, 0.1APT-2M Zn (OTf) 2 represents Example 1; Figure 3 Desolvation analysis of the electrolyte prepared in Example 1 and Comparative Example 1, wherein: Figure 3 a is a schematic diagram of the desolvation process of the electrolyte. Figure 3 b is the corresponding desolvation energy change, Figure 3 c is a comparison diagram of the activation energy of the electrolyte, in which 2 M Zn(OTf)2 represents Comparative Example 1 and 0.1APT-2M Zn(OTf)2 represents Example 1; Figure 4 The electrolyte Zn anode prepared in Example 1 and Comparative Example 1 is studied, wherein: Figure 4 a is a transmission electron microscopy comparison of the interface morphology of the Zn negative electrode after cycling. Figure 4 b is the X-ray diffraction pattern of the Zn negative electrode after cycling. Figure 4 c is a scanning electron microscopy comparison of the Zn negative electrode after cycling, in which 2 M Zn(OTf)2 represents Comparative Example 1 and 0.1APT-2M Zn(OTf2) represents Example 1; Figure 5 The electrolyte HB network prepared for Example 1 and Examples 5-7 is studied, wherein, Figure 5 a is a comparison chart of deuterated water spectra, Figure 5 b is the fitting curve of strong, medium and weak OH peaks of the electrolyte in Example 1, Figure 5 c is the evolution diagram of OH ratio of the electrolyte prepared in Example 1 and Examples 5-7, in which 2 M Zn(OTf)2 represents Comparative Example 1, 0.1APT-2M Zn(OTf)2 represents Example 1, Figure 5 In c, 0, 0.05, 0.1, 0.3, and 0.5 correspond to Example 1, Example 5, Example 1, Example 6, and Example 7, respectively; Figure 6 This is a graph showing the long cycle performance test of Zn / / Cu batteries assembled with the electrolytes prepared in Example 1 of the present invention and Comparative Example 1; Figure 7This is a graph showing the long cycle performance test of Zn / / Zn batteries assembled with the electrolytes prepared in Example 1 of the present invention and Comparative Example 1; Figure 8 This is a graph showing the long cycle performance test of Zn / / sodium vanadate (NVO) batteries assembled with the electrolytes prepared in Example 1 of the present invention and Comparative Example 1; Figure 9 This is a graph showing the long cycle performance test of Zn / / Zn batteries assembled with the electrolytes prepared in Example 1 of the present invention and Comparative Example 1 at -20°C; Figure 10 Long cycle performance test diagram of Zn / / Cu battery assembled with electrolyte prepared in Example 1 of the present invention and Comparative Example 1 at -20°C; Figure 11 Long-cycle performance test diagram of Zn / / sodium vanadate (NVO) battery assembled with the electrolyte prepared in Example 1 of the present invention at -30°C.

[0022] Figure 6-11 Here, 2 M Zn(OTf)2 represents Comparative Example 1, and 0.1APT-2M Zn(OTf)2 represents Example 1. DETAILED DESCRIPTION

[0023] The present invention will be further explained below with reference to specific implementation examples. The following implementation examples are only intended to provide a complete and clear explanation of the present invention. The described examples are only partial implementation examples of the present invention and do not constitute all implementation examples. All other implementation examples created based on this invention fall within the scope of protection of this invention.

[0024] Example 1 Add 18.1765 g Zn(CF3SO3)2 into a 25 mL volumetric flask, dilute to volume, and stir at 400 rpm for 0.5 h to completely disperse it. Prepare 25 mL of 2 mol·L -1 Zn(CF3SO3)2 electrolyte.

[0025] Accurately weigh 0.006 g of ammonium phosphotungstate (APT, CAS: 1311-90-6, purity 99%) and add it to 6 g of 2 mol·L -1APT was mixed with Zn(CF3SO3)2 electrolyte at room temperature and stirred at 400 rpm for 5 hours to homogenize the two solutions. After standing at room temperature for 30 minutes, the APT-Zn(CF3SO3)2 dispersion was syringe-filtered (filter diameter 0.22 μm) to obtain a 0.1%APT-Zn(CF3SO3)2 electrolyte solution with an APT mass fraction of approximately 0.1%. This 0.1%APT-Zn(CF3SO3)2 electrolyte solution was then assembled into an aqueous zinc-ion battery using a zinc sheet as the negative electrode and filter paper as the separator.

[0026] Example 2 Add 14.379 g ZnSO4·7H2O to a 25 mL volumetric flask, adjust the volume, and stir at 600 rpm for 2 h to completely disperse it. Prepare 25 mL of 2 mol·L -1 ZnSO4·7H2O electrolyte.

[0027] Accurately weigh 0.006 g of sodium phosphotungstate (SPT, CAS: 51312-42-6, purity 99%) and add it to 6 g of 2 mol·L -1 The SPT-ZnSO4·7H2O electrolyte was stirred at 400 rpm for 5 hours at room temperature to uniformly mix the SPT and ZnSO4·7H2O electrolyte. After standing at room temperature for 30 minutes, the SPT-ZnSO4·7H2O dispersion was syringe-filtered (filter size 0.22 μm) to obtain a 0.1%SPT-ZnSO4·7H2O electrolyte. An aqueous zinc-ion battery was assembled using a zinc sheet as the negative electrode and filter paper as the separator.

[0028] Example 3 Add 6.815 g ZnCl2 into a 25 mL volumetric flask, dilute to volume, and stir at 1000 rpm for 5 h to completely disperse it. Prepare 25 mL of 2 mol·L -1 ZnCl2 electrolyte.

[0029] Accurately weigh 0.018 g potassium phosphotungstate (KPT, purity 99%) and add it to 6 g of 2 mol·L -1 The KPT-ZnCl2 electrolyte was stirred at 1000 rpm for 12 hours at room temperature to uniformly mix the KPT and ZnCl2 electrolytes. After standing at room temperature for 30 minutes, the KPT-ZnCl2 dispersion was syringe-filtered (filter diameter 0.22 μm) to obtain a 0.3KPT-ZnCl2 electrolyte. An aqueous zinc-ion battery was assembled using a zinc sheet as the negative electrode and filter paper as the separator.

[0030] Example 4 Add 18.619 g Zn(ClO4)2·6H2O to a 25 mL volumetric flask, adjust the volume, and stir at 800 rpm for 3 h to completely disperse it. Prepare 25 mL of 2 mol·L -1 Zn(ClO4)2·6H2O electrolyte.

[0031] Accurately weigh 0.03 g of magnesium phosphotungstate (MPT, purity 99%) and add it to 6 g of 2 mol·L -1 MPT was stirred in a Zn(ClO4)2 electrolyte at room temperature and 1200 rpm for 18 hours to uniformly mix the MPT and Zn(ClO4)2·6H2O electrolyte. After standing at room temperature for 30 minutes, the MPT-Zn(ClO4)2·6H2O dispersion was syringe-filtered (filter size 0.22 μm) to obtain a 0.5MPT-Zn(ClO4)2·6H2O electrolyte. An aqueous zinc-ion battery was assembled using a zinc metal sheet as the negative electrode and filter paper as the separator.

[0032] Example 5 The 0.05APT-Zn(CF3SO3)2 electrolyte is basically the same as that in Example 1, except that the amount of ammonium phosphotungstate added is 0.003 g, and the rest is consistent with Example 1.

[0033] Example 6 The 0.3APT-Zn(CF3SO3)2 electrolyte is basically the same as that in Example 1, except that the amount of ammonium phosphotungstate added is 0.018 g, and the rest is consistent with Example 1.

[0034] Example 7 The 0.5APT-Zn(CF3SO3)2 electrolyte is basically the same as that in Example 1, except that the amount of ammonium phosphotungstate added is 0.030 g, and the rest is consistent with Example 1.

[0035] Example 8 The 0.01APT-Zn(CF3SO3)2 electrolyte is basically the same as that in Example 1, except that the amount of ammonium phosphotungstate added is 0.0006 g, and the rest remains the same as that in Example 1.

[0036] Example 9 5APT-Zn(CF3SO3)2 electrolyte is basically the same as that in Example 1, except that the amount of ammonium phosphotungstate added is 0.3 g, and the rest is consistent with that in Example 1.

[0037] Comparative Example 1 Add 18.1765 g Zn(CF3SO3)2 into a 25 mL volumetric flask, dilute to volume, and stir at 400 rpm for 0.5 h to completely disperse the solution. Prepare 25 mL of 2 mol·L -1 An aqueous zinc ion battery is assembled with a Zn(CF3SO3)2 electrolyte using a metal zinc sheet as the negative electrode and filter paper as the separator.

[0038] Comparative Example 2 Add 14.379 g ZnSO4·7H2O to a 25 mL volumetric flask, adjust the volume, and stir at 600 rpm for 2 h to completely disperse it. Prepare 25 mL of 2 mol·L -1 An aqueous zinc ion battery was assembled using a zinc sheet as the negative electrode and filter paper as the separator.

[0039] Experimental Example 1 The combustion test was carried out using the 0.1APT-Zn(CF3SO3)2 electrolyte prepared in Example 1 ( Figure 1 ), 1 ml of the electrolyte prepared in Example 1 in the positive electrode shell was ignited using a flame spray gun in an atmospheric environment. No combustion occurred within 10 s, demonstrating its excellent non-flammability.

[0040] Experimental Example 2 The 0.1APT-Zn(CF3SO3)2 electrolyte prepared in Example 1 was compared with the Zn(CF3SO3)2 electrolyte prepared in Comparative Example 1. Figure 2 a is the Zn content in different electrolytes 2+ Schematic diagram of the change in the ratio of solvation structure; through molecular dynamics simulation ( Figure 2 b, Simulations were performed using the Forcite module with a general force field in Materials Studio (MS) 2020. The system consists of 100 Zn(OTf)2, 1 APM nanoparticle, and 2078 H2O molecules) and Raman spectroscopy (Horiba LabRAM HR Evolution Raman spectrometer, Japan, with a scan range of 400–4000 cm -1 ) Test-SO3 Peak ( Figure 2 c) It can be seen that Zn in different electrolytes 2+ The solvation structure ratio changes, and the addition of APT promotes the 2+ The solvation structure of Zn is transformed from solvent-separated ion pairs (SSIP) and aggregates (FA) to contact ion pairs (CIP), which is beneficial to weaken the Zn 2+ -H2O solvation effect accelerates Zn2+ desolvation process.

[0041] Experimental Example 3 The 0.1APT-Zn(CF3SO3)2 electrolyte prepared in Example 1 was compared with the Zn(CF3SO3)2 electrolyte prepared in Comparative Example 1. Figure 3 a is a schematic diagram of the desolvation process of the electrolyte, and through theoretical calculation ( Figure 3 b, Quantum chemical calculations were performed using Gaussian 16 software, using a density-based solvation model and calculations of solvation free energies with water as the solvent) to verify [Zn(H2O)6] 2+ (Comparative Example 1) and [Zn(H2O)5(OTf)] + (Example 1) Stepwise desolvation of ions from [Zn(H2O)5(OTf)] + to [Zn(OTf)] + Each step of desolvation energy is lower than [Zn(H2O)6] 2+ The desolvation activation energy (E a ),like Figure 3 As shown in c, the E of 0.1APT-Zn(CF3SO3)2 a Value (30.05 kJ·mol -1 ) is lower than Zn(CF3SO3)2(40.61 kJ·mol -1 ), indicating that 0.1APT-Zn(CF3SO3)2 has faster desolvation kinetics.

[0042] Experimental Example 4 The 0.1APT-Zn(CF3SO3)2 electrolyte prepared in Example 1 was compared with the Zn(CF3SO3)2 electrolyte prepared in Comparative Example 1. The test was performed using a Neware battery tester (CT-4008) at 2 mA·cm -2 and 2 mAh·cm -2 The zinc negative electrode after 50 cycles under the same conditions. Figure 4 a) shows that a uniform electrolyte layer is formed in the 0.1APT-Zn(CF3SO3)2 electrolyte; X-ray diffraction (SmartLab SE X-ray diffractometer, scanning interval 5 o -80 o , the scanning speed is 10 o / min) test zinc negative electrode ( Figure 4b) The peak intensity ratio of Zn(002) / Zn(100) of the zinc negative electrode of 0.1APT-Zn(CF3SO3)2 (4.10) is significantly higher than that of Zn(CF3SO3)2 (1.90), indicating that the SEI layer can induce Zn 2+ The Zn(002) crystal plane was uniformly deposited. The Zn negative electrode morphology was observed by scanning electron microscopy (SU 8100 scanning electron microscope). Figure 4 c) The surface of the zinc negative electrode of 0.1APT-Zn(CF3SO3)2 showed a dense and flat morphology, while that of Zn(CF3SO3)2 showed a porous and rough surface. The above tests proved that the 0.1APT-Zn(CF3SO3)2 electrolyte was conducive to the formation of a uniform electrolyte layer, which promoted the 2+ Uniform deposition effectively avoids the formation of dendrites and by-products.

[0043] Experimental Example 5 The 0.1 M APT-Zn(CF3SO3)2 electrolyte prepared in Example 1 was compared with the 0.05 M APT-Zn(CF3SO3)2, 0.3 M APT-Zn(CF3SO3)2, and 0.5 M APT-Zn(CF3SO3)2 of Examples 5, 6, and 7, and the 2 M Zn(CF3SO3)2 electrolyte prepared in Comparative Example 1. The HNMR ( Figure 5 a) The participation of APT, 2 The H chemical shift shifted to the downfield, indicating that the hydrogen bonding between water molecules was weakened due to the interaction between APT and H2O. The results of Fourier transform infrared spectroscopy (NICOLET-iS50 FT-IR spectrometer, scanning range 400-4000 cm -1 , with a resolution of 4 cm -1 , scan number 64 times, tested by ATR mode) to test the OH peak change ( Figure 5 b, 5c), the ratio of strong, medium and weak OH in the electrolytes with different APT concentrations (0, 0.05, 0.1, 0.3 and 0.5 respectively correspond to Example 1, Example 5, Example 1, Example 6 and Example 7) changes. As the APT content increases, strong OH is converted into medium and weak OH, proving the role of APT in destroying the original hydrogen bond network of Zn(CF3SO3)2. Figure 5 It can be seen that the addition of APT effectively destroyed the HB network between water molecules and inhibited the activity of water molecules.

[0044] Experimental Example 6 Using the 0.1APT-Zn(CF3SO3)2 electrolyte prepared in Example 1 and the Zn(CF3SO3)2 electrolyte prepared in Comparative Example 1, AZIBs were assembled with metal zinc sheet as the negative electrode and filter paper as the separator. Cyclic charge and discharge tests were carried out on a Neware battery tester (CT-4008) to evaluate the performance of CR2025 button batteries.

[0045] Figure 6 The assembled Zn / / Cu battery (with copper foil as positive electrode, zinc sheet as negative electrode, and filter paper as separator) was tested at a current density of 1 mA·cm -2 and an area capacity of 0.5 mAh·cm -2 The coulombic efficiency was evaluated under constant temperature of 25°C and normal pressure. The APT additive promoted the desolvation kinetics and optimized the state of the H2O molecules, achieving a first-cycle coulombic efficiency of 84.26% and an average coulombic efficiency of 99.65% within 2400 h. The comparative example 1 only cycled for 250 h and had an average coulombic efficiency of only 98.12%.

[0046] Figure 7 The assembled Zn / / Zn battery (with metal zinc sheets as positive and negative electrodes and filter paper as separator) was tested at a current density of 2 mA cm -2 and an area capacity of 2 mAh·cm -2 The cycle performance was tested under constant temperature of 25°C and normal pressure. Comparative Example 1 only cycled for 200 h and had a larger polarization voltage. The addition of APT showed a longer cycle life and a lower polarization voltage.

[0047] Figure 8 The assembled Zn / / NVO full battery (with sodium vanadate as the positive electrode, metal zinc sheet as the negative electrode, and filter paper as the separator) was tested at a current density of 5 A·g -1 and areal capacity 0.5 mAh·cm -2 The cycle performance was tested under the conditions of constant temperature 25°C and normal pressure. Comparative Example 1 only cycled 900 times and had a lower capacity, while after adding APT, it showed 293.1 mAh·g -1 The initial specific capacity is 2.533 W, and the capacity retention rate is close to 100% after 3300 cycles. The electrochemical performance test shows that the addition of APT optimizes the electrolyte stability and electrolyte-zinc interface.

[0048] Experimental Example 7 Using the 0.1APT-Zn(CF3SO3)2 electrolyte prepared in Example 1 and the Zn(CF3SO3)2 electrolyte prepared in Comparative Example 1, AZIBs were assembled with metal zinc sheet as the negative electrode and filter paper as the diaphragm. Cyclic charge and discharge tests were carried out on a Neware battery tester (CT-4008) to evaluate the low-temperature cycling performance of CR2025 button batteries.

[0049] Figure 9 The assembled Zn / / Zn battery (with metal zinc sheets as positive and negative electrodes and filter paper as separator) was tested at a current density of 0.5 mA cm -2 and an area capacity of 0.5 mAh·cm -2 The cycle performance was tested under -20℃ and normal pressure conditions. Comparative Example 1 only cycled for 320 h and had a large polarization voltage. The addition of APT showed a longer cycle life (1800 h) and a lower polarization voltage.

[0050] Figure 10 The assembled Zn / / Cu battery (with copper foil as positive electrode, zinc sheet as negative electrode, and filter paper as separator) was tested at a current density of 1 mA·cm -2 and an area capacity of 0.5 mAh·cm -2 The coulombic efficiency was evaluated under -20℃ and normal pressure conditions. Comparative Example 1 could only cycle 50 times and the average coulombic efficiency was only 96.15%. After adding APT, the average coulombic efficiency within 1000 hours was as high as 99.00% at low temperature.

[0051] Figure 11 The assembled Zn / / NVO full battery (sodium vanadate as positive electrode, metal zinc sheet as negative electrode, filter paper as separator) was tested at a current density of 0.2 A·g -1 and areal capacity 0.5 mAh·cm -2 The cycling performance was tested at -30°C and atmospheric pressure, showing an average specific capacity of 170 mAh g at low temperatures. -1 , and the capacity retention rate is close to 100% after 750 cycles, with excellent performance.

[0052] The various technical features of the above-described embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the various technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should all be considered to be within the scope of this specification. The description of the above implementation cases can be used to help understand the principles and methods of the present invention. However, the above implementation cases are not exclusive and should not be construed as limiting the present invention. At the same time, for those skilled in the art, according to the principles and methods of the present invention, flexible changes can be made in the specific implementation methods and application scopes.

Claims

1. Application of a trace diluent type high-nuclear inorganic salt in an electrolyte, characterized in that: The specific steps are as follows: (1) Dissolve zinc salt in deionized water and stir thoroughly to dissolve it to obtain a blank electrolyte; (2) Dispersing a diluent-type high-nuclear inorganic salt in a blank electrolyte, stirring to dissolve and filtering to obtain an electrolyte; The high-nuclear inorganic salt in step (2) is a Keggin-type phosphotungstate; The concentration of the zinc salt in step (1) is 1~5 mol•L -1 ; The mass fraction of diluent-type high-nuclear inorganic salts is 0.01%~5%.

2. The use of the trace diluent type high-nuclear inorganic salt in an electrolyte according to claim 1, characterized in that: The diluent-type high-nuclear inorganic salt is selected from a mixture of one or more of ammonium phosphotungstate, potassium phosphotungstate, sodium phosphotungstate, and magnesium phosphotungstate.

3. The use of the trace diluent type high-nuclear inorganic salt in an electrolyte according to claim 1 or 2, characterized in that: The zinc salt in step (1) is a mixture of one or more of zinc sulfate, zinc chloride, zinc trifluoromethanesulfonate, zinc perchlorate, and zinc acetate.

4. The use of the trace diluent type high-nuclear inorganic salt in an electrolyte according to claim 1 or 2, characterized in that: The mass fraction of diluent-type high-nuclear inorganic salts is 0.1%~0.5%.

5. The use of the trace diluent type high-nuclear inorganic salt in an electrolyte according to claim 1 or 2, characterized in that: The stirring rate in step (1) is 400-1000 rpm, and the stirring time is 0.5-5 h.

6. The use of the trace diluent type high-nuclear inorganic salt in an electrolyte according to claim 1 or 2, characterized in that: The stirring rate in step (2) is 400-1200 rpm, and the stirring time is 5-18 h.

7. The use of the trace diluent type high-nuclear inorganic salt in an electrolyte according to claim 1 or 2, characterized in that: Before filtering in step (2), the stirred and dissolved electrolyte is allowed to stand at room temperature for 10 to 40 minutes.

8. The use of the trace diluent type high-nuclear inorganic salt in an electrolyte according to claim 1 or 2, characterized in that: The filtration accuracy in step (2) is 0.22 μm.

9. The use of the trace diluent type high-nuclear inorganic salt in an electrolyte according to claim 1 or 2, characterized in that: After obtaining the electrolyte in step (2), a button battery is assembled using a metal zinc sheet as the negative electrode and filter paper as the separator.

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