Preparation method of poly (1, 3-dioxolame)-based composite electrolyte

Abstract

The invention discloses a preparation method of a poly (1, 3-dioxolame)-based composite electrolyte, and belongs to the technical field of sodium ion batteries. The preparation method comprises the following steps: adding a sodium salt and a 1, 3-dioxolame monomer into a solvent, then mixing with an additive to obtain a precursor, and carrying out standing and polymerization curing treatment to obtain the poly (1, 3-dioxolame)-based composite electrolyte. According to the invention, the polymerization curing time of the precursor is greatly shortened by optimizing a solvent system; the additive is introduced into the precursor, the additive comprises a cross-linking agent and / or an inorganic filler, the cross-linking agent is trimethylolpropane triglycidyl ether, and the inorganic filler is NASICON type solid electrolyte powder, so that the ionic conductivity of the poly (1, 3-dioxolame)-based composite electrolyte is effectively improved, and the service life of the poly (1, 3-dioxolame)-based composite electrolyte is prolonged. And the cycling stability and the first-cycle discharge specific capacity of the assembled battery are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium ion batteries, and in particular to a method for preparing a poly (1,3-dioxolane)-based composite electrolyte. Background Art

[0002] With the rapid development of new energy technologies, sodium-ion batteries (Na-ion batteries) have become an important complement to lithium-ion batteries due to their abundant resources and low cost. However, conventional liquid electrolyte Na-ion batteries pose safety risks such as flammability and leakage, and face bottlenecks in increasing their energy density. Therefore, the development of solid-state Na-ion batteries that combine high safety with high energy density has become a current research hotspot.

[0003] Solid electrolytes, as the core components of solid-state batteries, can be divided into inorganic solid electrolytes, organic solid electrolytes and organic-inorganic composite solid electrolytes according to the material system. Among them, organic-inorganic composite solid electrolytes combine the advantages of inorganic and organic materials and have been widely studied. In addition, in-situ prepared solid electrolytes can improve the interfacial compatibility between solid electrolytes and electrodes, and the preparation process is compatible with existing processes, and has significant industrialization potential. However, the existing solid electrolytes still have the following key problems that need to be solved: First, the polymerization time is too long: the polymerization time of 1,3-dioxolane (DOL) at 60°C is usually more than 12 hours, the time cost is high, the production efficiency is low, and it is difficult to meet the needs of large-scale production; second, the ionic conductivity is insufficient. The ionic conductivity of the solid electrolyte based on poly (1,3-dioxolane) (PDOL) is low, only about 10 -5 S·cm⁻¹, resulting in poor battery kinetics and making it difficult to stably cycle at rates of 0.2C and above. Therefore, a new method for preparing poly(1,3-dioxolane)-based composite electrolytes is urgently needed. By optimizing the preparation process, the polymerization time can be significantly shortened and the ionic conductivity can be improved, thereby promoting the practical application of high-performance solid-state sodium batteries. Summary of the Invention

[0004] The present invention aims to provide a method for preparing a poly(1,3-dioxolane)-based composite electrolyte, which not only significantly shortens the polymerization and curing time of the 1,3-dioxolane monomer and significantly improves production efficiency; but also effectively improves the cycle stability of the poly(1,3-dioxolane)-based composite electrolyte, increases the first-cycle discharge specific capacity and ionic conductivity, and optimizes the electrochemical performance of the poly(1,3-dioxolane)-based composite electrolyte.

[0005] The technical solutions adopted by the present invention to achieve the above-mentioned purpose are: A method for preparing a poly(1,3-dioxolane)-based composite electrolyte comprises: adding a sodium salt and a 1,3-dioxolane monomer into a solvent, and then mixing the mixture with an additive to obtain a precursor; then allowing the precursor to stand at room temperature, and heating the precursor to initiate polymerization and curing to obtain the poly(1,3-dioxolane)-based composite electrolyte; the additive comprises a crosslinking agent and / or an inorganic filler, wherein the crosslinking agent is trimethylolpropane triglycidyl ether, and the inorganic filler is NASICON solid electrolyte powder; the volume of the crosslinking agent is equivalent to 1.5-3% of the volume of the 1,3-dioxolane monomer, and the mass of the inorganic filler is equivalent to 1.5-3% by weight of the volume of the 1,3-dioxolane monomer.

[0006] The present invention significantly shortens the polymerization and curing time of 1,3-dioxolane monomers by optimizing the solvent system, thereby significantly improving production efficiency. At the same time, a cross-linking agent and an inorganic filler are introduced into the precursor. The cross-linking agent copolymerizes with the 1,3-dioxolane monomer to form a three-dimensional cross-linked network structure, and the inorganic filler constructs a fast ion transmission path. The two act synergistically to effectively improve the ionic conductivity of the poly (1,3-dioxolane)-based composite solid electrolyte.

[0007] Preferably, the mass of the sodium salt is equivalent to 4-8 wt% of the volume of the 1,3-dioxolane monomer.

[0008] Preferably, the sodium salt includes at least one of sodium hexafluorophosphate and sodium bis(trifluoromethanesulfonyl)imide.

[0009] Preferably, the volume of the solvent is equivalent to 20-70% of the volume of the 1,3-dioxolane monomer.

[0010] Preferably, the solvent includes sodium hexafluorophosphate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate and fluoroethylene carbonate.

[0011] Preferably, the polymerization curing temperature is 50-60° C., and the polymerization curing time is 3-15 hours.

[0012] Preferably, the additive further includes a functional agent.

[0013] More preferably, the functional agent includes succinonitrile, vanillyl alcohol ethyl ether, and dihydromyrcenol. The present invention introduces the functional agent into the preparation of a poly(1,3-dioxolane)-based composite electrolyte. This may significantly enhance the electrolyte's ionic conductivity by increasing the spatial activity of the polymer backbone chain, reducing the crystallinity of the polymer electrolyte, and increasing the amorphous orientation of the polymer electrolyte. This optimizes the electrolyte interface stability and significantly improves the first-cycle discharge capacity of batteries assembled from the electrolyte.

[0014] More preferably, the mass of vanillyl alcohol ethyl ether is equivalent to 10-20 wt% of the volume of succinonitrile.

[0015] More preferably, the volume of dihydromyrcenol is equivalent to 8-15% of the volume of succinonitrile.

[0016] Preferably, the preparation of the precursor is specifically as follows: Sodium salt and 1,3-dioxolane monomer (DOL) are added into a solvent, and additives are added to obtain a precursor.

[0017] Preferably, the mass of the sodium salt is equivalent to 4-8 wt% of the volume of the DOL.

[0018] Preferably, the sodium salt is sodium hexafluorophosphate (NaPF6).

[0019] Preferably, the sodium salt is a mixture of sodium hexafluorophosphate (NaPF6) and sodium bis(trifluoromethanesulfonyl)imide (NaTFSI).

[0020] More preferably, the mass of NaTFSI is equivalent to 1-2 times the mass of NaPF6.

[0021] Preferably, the volume of the solvent corresponds to 20-70% of the volume of the DOL.

[0022] Preferably, the solvent includes sodium hexafluorophosphate (NaPF6), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC) and fluoroethylene carbonate (FEC).

[0023] More preferably, the mass of NaPF6 is equivalent to 20-40 wt% of the volume of PC.

[0024] More preferably, the volume of the EMC is equivalent to 70-90% of the volume of the PC.

[0025] More preferably, the volume of DEC is equivalent to 4-6% of the volume of PC.

[0026] More preferably, the volume of FEC is equivalent to 2-4% of the volume of PC.

[0027] Preferably, the additive includes at least one of a cross-linking agent, an inorganic filler, and a functional agent.

[0028] More preferably, the volume of the cross-linking agent is equivalent to 1-2% of the volume of the DOL.

[0029] More preferably, the crosslinking agent is trimethylolpropane triglycidyl ether (TMPTGE).

[0030] More preferably, the mass of the inorganic filler is equivalent to 1-2 wt% of the volume of the DOL.

[0031] More preferably, the inorganic filler is NASICON type solid electrolyte powder.

[0032] More preferably, the mass of the functional agent is equivalent to 0.2-1 wt% of the volume of the DOL.

[0033] More preferably, the functional agent includes at least one of succinonitrile, vanillyl alcohol ethyl ether, dihydromyrcenol, and propylene glycol methyl ether propionate. The present invention further introduces propylene glycol methyl ether propionate into the functional agent, potentially promoting sodium ion migration and improving interfacial compatibility, thereby further enhancing the first-cycle discharge capacity and ionic conductivity of the prepared poly(1,3-dioxolane)-based composite electrolyte.

[0034] More preferably, the mass of vanillyl alcohol ethyl ether is equivalent to 10-20 wt% of the volume of succinonitrile.

[0035] More preferably, the volume of dihydromyrcenol is equivalent to 8-15% of the volume of succinonitrile.

[0036] More preferably, the mass of propylene glycol methyl ether propionate is equivalent to 2-6 wt % of the volume of succinonitrile.

[0037] Preferably, the preparation of the poly(1,3-dioxolane)-based composite electrolyte comprises: The precursor is allowed to stand at room temperature for 5-8 hours, and is heated at 50-60° C. to initiate polymerization of the precursor to obtain a poly (1,3-dioxolane) based composite electrolyte.

[0038] The polymerization time of the precursor using the self-mixed solvent at 50°C is only 3 hours, and the ionic conductivity of the poly (1,3-dioxolane) based composite solid electrolyte with the addition of a cross-linking agent and solid electrolyte powder can reach 10 -4 S / cm, the assembled button cell with single crystal layer oxygen cathode can be stably cycled at 0.2C.

[0039] The present invention uses succinonitrile, vanillyl alcohol ethyl ether, dihydromyrcenol and propylene glycol methyl ether propionate to prepare a functional agent, uses the functional agent in the preparation of a precursor, and obtains a poly(1,3-dioxolane)-based composite electrolyte through standing and polymerization curing treatment. Therefore, the present invention has the following beneficial effects: the poly(1,3-dioxolane)-based composite solid electrolyte prepared by the present invention has a high first-week discharge specific capacity and high ionic conductivity. The first-week discharge specific capacity is 110-153.8, and the ionic conductivity is 1.03×10 -4 -7.36×10 -4 Therefore, the present invention provides a method for preparing a poly (1,3-dioxolane) based composite solid electrolyte with high first cycle discharge specific capacity and high ion conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The poly (1,3-dioxolane) based composite electrolyte prepared in Example 5.

[0041] Figure 2 This is the poly (1,3-dioxolane) based composite electrolyte prepared in Comparative Example 1.

[0042] Figure 3 Cycling stability of poly (1,3-dioxolane) based composite electrolytes.

[0043] Figure 4 The cross-linking impedance spectrum of Example 2-5.

[0044] Figure 5 is the ionic conductivity of Example 2-5. DETAILED DESCRIPTION

[0045] The present invention will be further described in detail below in conjunction with specific embodiments. The examples provided are only for illustrating the present invention and are not intended to limit the scope of the present invention. The examples provided below can serve as a guide for further improvements by those skilled in the art and are not intended to limit the present invention in any way.

[0046] The experimental methods in the following examples are conventional methods unless otherwise specified. The materials and reagents used in the following examples are commercially available unless otherwise specified.

[0047] Example 1: Preparation of precursors, including Sodium salt and 1,3-dioxolane monomer (DOL) are added to a solvent to obtain a precursor. The mass of the sodium salt is equivalent to 6.25wt% of the volume of DOL, and the volume of the solvent is equivalent to 50% of the volume of DOL. The sodium salt is sodium hexafluorophosphate (NaPF6). The solvent includes sodium hexafluorophosphate (NaPF6), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC) and fluoroethylene carbonate (FEC). The mass of NaPF6 is equivalent to 30wt% of the volume of PC, the volume of EMC is equivalent to 77% of the volume of PC, the volume of DEC is equivalent to 4.3% of the volume of PC, and the volume of FEC is equivalent to 2.1% of the volume of PC.

[0048] Preparation of poly (1,3-dioxolane) based composite electrolyte, comprising, The precursor was allowed to stand at room temperature for 5 hours and then heated at 50°C to initiate polymerization and curing of the precursor to obtain a poly (1,3-dioxolane) based composite electrolyte.

[0049] Example 2: Preparation of precursors, including Sodium salt and 1,3-dioxolane monomer (DOL) are added to a solvent to obtain a precursor. The mass of the sodium salt is equivalent to 6.25wt% of the volume of DOL, and the volume of the solvent is equivalent to 50% of the volume of DOL. The sodium salt is a mixture of sodium hexafluorophosphate (NaPF6) and sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), and the mass of NaTFSI is equivalent to 1 times the mass of NaPF6. The solvent includes sodium hexafluorophosphate (NaPF6), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and fluoroethylene carbonate (FEC). The mass of NaPF6 is equivalent to 30wt% of the volume of PC, the volume of EMC is equivalent to 77% of the volume of PC, the volume of DEC is equivalent to 4.3% of the volume of PC, and the volume of FEC is equivalent to 2.1% of the volume of PC.

[0050] The preparation of the poly (1,3-dioxolane) based composite electrolyte was carried out under the same conditions as in Example 1 except that the precursor was replaced with the precursor prepared in this example.

[0051] Example 3: Preparation of precursors, including A sodium salt and 1,3-dioxolane monomer (DOL) were added to a solvent, along with a crosslinker, to produce a precursor. The sodium salt mass was equivalent to 6.25wt% of the DOL volume, the solvent volume was equivalent to 50% of the DOL volume, and the crosslinker volume was equivalent to 1.6% of the DOL volume. The sodium salt was a mixture of sodium hexafluorophosphate (NaPF6) and sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), with the mass of NaTFSI being equivalent to 1 / the mass of NaPF6. The solvent consisted of sodium hexafluorophosphate (NaPF6), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and fluoroethylene carbonate (FEC). The mass of NaPF6 was equivalent to 30wt% of the PC volume, the volume of EMC was equivalent to 77% of the PC volume, the volume of DEC was equivalent to 4.3% of the PC volume, and the volume of FEC was equivalent to 2.1% of the PC volume. The crosslinker was trimethylolpropane triglycidyl ether (TMPTGE).

[0052] The preparation of the poly (1,3-dioxolane) based composite electrolyte was carried out under the same conditions as in Example 1 except that the precursor was replaced with the precursor prepared in this example.

[0053] Example 4: Preparation of precursors, including A sodium salt and 1,3-dioxolane monomer (DOL) were added to a solvent, followed by an inorganic filler, to produce a precursor. The sodium salt was equivalent to 6.25 wt% of the DOL volume, the solvent was equivalent to 50% of the DOL volume, and the inorganic filler was equivalent to 1.6 wt% of the DOL volume. The sodium salt was a mixture of sodium hexafluorophosphate (NaPF6) and sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), with the mass of NaTFSI being equivalent to twice the mass of NaPF6. The solvent consisted of sodium hexafluorophosphate (NaPF6), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and fluoroethylene carbonate (FEC). The mass of NaPF6 was equivalent to 30 wt% of the PC volume, the volume of EMC was equivalent to 77% of the PC volume, the volume of DEC was equivalent to 4.3% of the PC volume, and the volume of FEC was equivalent to 2.1% of the PC volume. The inorganic filler was NASICON solid electrolyte powder purchased from Dongguan Kelude New Energy Technology Co., Ltd.

[0054] The preparation of the poly (1,3-dioxolane) based composite electrolyte was carried out under the same conditions as in Example 1 except that the precursor was replaced with the precursor prepared in this example.

[0055] Example 5: Preparation of precursors, including A sodium salt and 1,3-dioxolane monomer (DOL) were added to a solvent, along with a crosslinker and inorganic filler, to produce a precursor. The sodium salt weight was equivalent to 6.25wt% of the DOL volume, the solvent volume was equivalent to 50% of the DOL volume, the crosslinker volume was equivalent to 1.6% of the DOL volume, and the inorganic filler volume was equivalent to 1.6wt% of the DOL volume. The sodium salt was a mixture of sodium hexafluorophosphate (NaPF6) and sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), with the mass of NaTFSI being equivalent to twice the mass of NaPF6. The solvent consisted of sodium hexafluorophosphate (NaPF6), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and fluoroethylene carbonate (FEC). The mass of NaPF6 was equivalent to 30wt% of the PC volume, the volume of EMC was equivalent to 77% of the PC volume, the volume of DEC was equivalent to 4.3% of the PC volume, and the volume of FEC was equivalent to 2.1% of the PC volume. The crosslinker was trimethylolpropane triglycidyl ether (TMPTGE). The inorganic filler is NASICON solid electrolyte powder, which is purchased from Dongguan Kelude New Energy Technology Co., Ltd.

[0056] The preparation of the poly (1,3-dioxolane) based composite electrolyte was carried out under the same conditions as in Example 1 except that the precursor was replaced with the precursor prepared in this example.

[0057] Example 6: Preparation of precursors, including A sodium salt and 1,3-dioxolane monomer (DOL) were added to a solvent, along with a crosslinker, inorganic filler, and functional agent to produce a precursor. The sodium salt weight was equivalent to 6.25wt% of the DOL volume, the solvent volume was equivalent to 50% of the DOL volume, the crosslinker volume was equivalent to 1.6% of the DOL volume, the inorganic filler volume was equivalent to 1.6wt% of the DOL volume, and the functional agent volume was equivalent to 1wt% of the DOL volume. The sodium salt was a mixture of sodium hexafluorophosphate (NaPF6) and sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), with the mass of NaTFSI being equivalent to 1 / the mass of NaPF6. The solvent consisted of sodium hexafluorophosphate (NaPF6), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and fluoroethylene carbonate (FEC). The mass of NaPF6 was equivalent to 30wt% of the PC volume, the volume of EMC was equivalent to 77% of the PC volume, the volume of DEC was equivalent to 4.3% of the PC volume, and the volume of FEC was equivalent to 2.1% of the PC volume. The crosslinker was trimethylolpropane triglycidyl ether (TMPTGE). The inorganic filler was NASICON solid electrolyte powder, purchased from Dongguan Kelude New Energy Technology Co., Ltd. The functional agents included succinonitrile, vanillyl alcohol ethyl ether, and dihydromyrcenol. The mass of vanillyl alcohol ethyl ether was equivalent to 20 wt% of the volume of succinonitrile, and the volume of dihydromyrcenol was equivalent to 15% of the volume of succinonitrile.

[0058] The preparation of the poly (1,3-dioxolane) based composite electrolyte was carried out under the same conditions as in Example 1 except that the precursor was replaced with the precursor prepared in this example.

[0059] Example 7: The preparation of the precursor was performed under the same conditions as in Example 6 except that the mass of vanillyl alcohol ethyl ether was changed to 10 wt % of the volume of succinonitrile.

[0060] The preparation of the poly (1,3-dioxolane) based composite electrolyte was carried out under the same conditions as in Example 1 except that the precursor was replaced with the precursor prepared in this example.

[0061] Example 8: The preparation of the precursor was carried out under the same conditions as in Example 6, except that the volume of dihydromyrcenol was changed to 5% of the volume of succinonitrile.

[0062] The preparation of the poly (1,3-dioxolane) based composite electrolyte was carried out under the same conditions as in Example 1 except that the precursor was replaced with the precursor prepared in this example.

[0063] Example 9: Preparation of precursors, including A sodium salt and 1,3-dioxolane monomer (DOL) were added to a solvent, along with a crosslinker, inorganic filler, and functional agent to produce a precursor. The sodium salt weight was equivalent to 6.25wt% of the DOL volume, the solvent volume was equivalent to 50% of the DOL volume, the crosslinker volume was equivalent to 1.6% of the DOL volume, the inorganic filler volume was equivalent to 1.6wt% of the DOL volume, and the functional agent volume was equivalent to 1wt% of the DOL volume. The sodium salt was a mixture of sodium hexafluorophosphate (NaPF6) and sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), with the mass of NaTFSI being equivalent to 1 / the mass of NaPF6. The solvent consisted of sodium hexafluorophosphate (NaPF6), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and fluoroethylene carbonate (FEC). The mass of NaPF6 was equivalent to 30wt% of the PC volume, the volume of EMC was equivalent to 77% of the PC volume, the volume of DEC was equivalent to 4.3% of the PC volume, and the volume of FEC was equivalent to 2.1% of the PC volume. The crosslinker was trimethylolpropane triglycidyl ether (TMPTGE). The inorganic filler was NASICON solid electrolyte powder, purchased from Dongguan Kelude New Energy Technology Co., Ltd. The functional agents included succinonitrile, vanillyl alcohol ethyl ether, dihydromyrcenol, and propylene glycol methyl ether propionate. The mass of vanillyl alcohol ethyl ether was equivalent to 20% by weight of succinonitrile, the volume of dihydromyrcenol was equivalent to 15% by volume of succinonitrile, and the mass of propylene glycol methyl ether propionate was equivalent to 6% by volume of succinonitrile.

[0064] The preparation of the poly (1,3-dioxolane) based composite electrolyte was carried out under the same conditions as in Example 1 except that the precursor was replaced with the precursor prepared in this example.

[0065] Example 10: The preparation of the precursor was similar to that of Example 9 except that the mass of propylene glycol methyl ether propionate was replaced by 2 wt % of the volume of succinonitrile. Other conditions were the same as those of Example 9.

[0066] The preparation of the poly (1,3-dioxolane) based composite electrolyte was carried out under the same conditions as in Example 1 except that the precursor was replaced with the precursor prepared in this example.

[0067] Comparative Example 1: Preparation of precursors, including A sodium salt and 1,3-dioxolane monomer (DOL) were added to a high-voltage electrolyte, along with a crosslinker and inorganic filler, to produce a precursor. The sodium salt mass was equivalent to 6.25wt% of the DOL volume, the high-voltage electrolyte volume was equivalent to 50% of the DOL volume, the crosslinker volume was equivalent to 1.6% of the DOL volume, and the inorganic filler mass was equivalent to 1.6wt% of the DOL volume. The sodium salt was a mixture of sodium hexafluorophosphate (NaPF6) and sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), with the mass of NaTFSI being equivalent to twice the mass of NaPF6. The high-voltage electrolyte was purchased from Zhejiang Sodium Innovation Energy Co., Ltd. The crosslinker was trimethylolpropane triglycidyl ether (TMPTGE). The inorganic filler was NASICON solid electrolyte powder, purchased from Dongguan Kelude New Energy Technology Co., Ltd.

[0068] The preparation of the poly (1,3-dioxolane) based composite electrolyte was carried out under the same conditions as in Example 1 except that the precursor was replaced with the precursor prepared in this example.

[0069] Comparative Example 2: The preparation of the precursor was carried out under the same conditions as in Example 6 except that dihydromyrcenol was not used.

[0070] The preparation of the poly (1,3-dioxolane) based composite electrolyte was carried out under the same conditions as in Example 1 except that the precursor was replaced with the precursor prepared in this example.

[0071] Comparative Example 3: The preparation of the precursor was performed under the same conditions as in Example 6 except that vanillyl alcohol ethyl ether was not used.

[0072] The preparation of the poly (1,3-dioxolane) based composite electrolyte was carried out under the same conditions as in Example 1 except that the precursor was replaced with the precursor prepared in this example.

[0073] Comparative Example 4: The preparation of the precursor was carried out under the same conditions as in Example 9 except that vanillyl alcohol ethyl ether and dihydromyrcenol were not used.

[0074] The preparation of the poly (1,3-dioxolane) based composite electrolyte was carried out under the same conditions as in Example 1 except that the precursor was replaced with the precursor prepared in this example.

[0075] Experimental example: 1. Precursor polymerization and curing conditions Figure 1 The poly (1,3-dioxolane) based composite electrolyte prepared in Example 5, Figure 2 This is the poly(1,3-dioxolane)-based composite electrolyte prepared in Comparative Example 1. The precursor in Example 5 solidified after standing at room temperature for 5 hours and then heating at 50°C for 3 hours, losing its fluidity. The precursor in Comparative Example 1 solidified after standing at room temperature for 5 hours and then heating at 50°C for 15 hours, losing its fluidity. This is because the solvent components used in the preparation of the precursors differ: the solvent used in Example 5 includes propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and fluoroethylene carbonate (FEC), while the solvent used in Comparative Example 1 is a high-voltage electrolyte produced by Zhejiang Sodium Innovation Energy Co., Ltd. This demonstrates that using the solvent system of the present invention to prepare the precursor, then introducing a crosslinker and inorganic filler, standing at room temperature for 5 hours, and then heating at 50°C to initiate polymerization and curing, can significantly shorten the precursor polymerization and curing time, thereby effectively improving production efficiency.

[0076] 2. Cyclic stability Button cells were constructed using the poly(1,3-dioxolane)-based composite electrolytes prepared in Examples 1-10 and Comparative Examples 1-4, with metallic sodium as the negative electrode. The cycling stability of the poly(1,3-dioxolane)-based composite electrolytes prepared in Examples 1-10 and Comparative Examples 1-4 was tested by cycling them at a 0.2C rate for 25 cycles.

[0077] Figure 3 Regarding the cycling stability of the poly(1,3-dioxolane)-based composite electrolyte, Example 5 exhibited superior first-cycle discharge capacity and cycling stability compared to Example 2. This was due to the inclusion of a crosslinker and inorganic filler in the preparation of the poly(1,3-dioxolane)-based composite electrolyte, while Example 2 did not. The superior first-cycle discharge capacity and cycling stability of Example 5 compared to Examples 3-4 were also due to the combined use of a crosslinker and inorganic filler in the preparation of the poly(1,3-dioxolane)-based composite electrolyte, while Example 3 and Example 4 used only a crosslinker and inorganic filler, respectively. This demonstrates that the combined use of a crosslinker and inorganic filler significantly improves the first-cycle discharge capacity and cycling stability of the poly(1,3-dioxolane)-based composite electrolyte compared to their use alone.

[0078] Table 1 Discharge capacity in the first week (mAh / g)

[0079] As can be seen from Table 1, the first-week discharge specific capacity of Examples 6-8 of the present invention is higher than that of Example 5 because, in the preparation of the poly(1,3-dioxolane)-based composite electrolyte, Examples 6-8 introduce functional agents, which include succinonitrile, vanillyl alcohol ethyl ether, and dihydromyrcenol. The first-week discharge specific capacity of Example 6 is higher than that of Examples 7 and 8 because the amounts of vanillyl alcohol ethyl ether and dihydromyrcenol used in the preparation of the poly(1,3-dioxolane)-based composite electrolyte are different. The first-week discharge specific capacity of Example 6 is higher than that of Comparative Examples 2 and 3 because, in the preparation of the poly(1,3-dioxolane)-based composite electrolyte, Example 5 uses vanillyl alcohol ethyl ether and dihydromyrcenol in combination, while Comparative Example 2 uses vanillyl alcohol ethyl ether alone, and Comparative Example 3 uses dihydromyrcenol alone. This shows that compared with the use of vanillyl alcohol ethyl ether and dihydromyrcenol alone, the synergistic use of vanillyl alcohol ethyl ether and dihydromyrcenol as functional agents can effectively improve the first-cycle discharge specific capacity of the prepared poly (1,3-dioxolane) based composite electrolyte.

[0080] The higher first-cycle discharge capacity of Examples 9-10 of the present invention than that of Example 6 is due to the addition of propylene glycol methyl ether propionate to the functional agent in the preparation of the poly(1,3-dioxolane)-based composite electrolyte. The higher first-cycle discharge capacity of Example 9 than that of Example 10 is due to the different amounts of propylene glycol methyl ether propionate used in the preparation of the poly(1,3-dioxolane)-based composite electrolyte. The higher first-cycle discharge capacity of Example 9 than that of Comparative Example 4 is due to the use of propylene glycol methyl ether propionate alone, without vanillyl alcohol ethyl ether and dihydromyrcenol, in the preparation of the poly(1,3-dioxolane)-based composite electrolyte in Comparative Example 5. This indicates that the further addition of propylene glycol methyl ether propionate to the functional agent in the preparation of the poly(1,3-dioxolane)-based composite electrolyte can further improve the first-cycle discharge capacity of the prepared poly(1,3-dioxolane)-based composite electrolyte.

[0081] 3. Conductivity test Button cells were constructed using the poly(1,3-dioxolane)-based composite electrolytes prepared in Examples 1-10 and Comparative Examples 1-4, with metallic sodium as the negative electrode. Conductivity tests were performed using an electrochemical workstation from Shanghai Chenhua Instrument Co., Ltd.

[0082] Figure 4 is the cross-linking impedance spectrum of Example 2-5, Figure 5 is the ionic conductivity of Example 2-5. Figure 4 and Figure 5 It can be seen that the ionic conductivity of the poly (1,3-dioxolane) based composite electrolyte prepared in Example 2 is 3.1×10 -5 S / cm, and the ionic conductivity of the poly (1,3-dioxolane) based composite electrolyte prepared in Example 3 is 4.5×10-5 S / cm, and the ionic conductivity of the poly (1,3-dioxolane) based composite electrolyte prepared in Example 4 was 5.1×10 -5 S / cm, and the ionic conductivity of the poly (1,3-dioxolane) based composite electrolyte prepared in Example 5 was 1.03×10 -4 S / cm. The ionic conductivity of Example 5 is significantly higher than that of Examples 2-3 because, in the preparation of the poly(1,3-dioxolane)-based composite electrolyte, Example 5 uses a crosslinker and an inorganic filler in combination, while Example 2 does not use a crosslinker and an inorganic filler, Example 3 uses only a crosslinker, and Example 4 uses only an inorganic filler. This indicates that the combined use of a crosslinker and an inorganic filler can significantly improve the ionic conductivity of the poly(1,3-dioxolane)-based composite electrolyte compared to using a crosslinker and an inorganic filler alone.

[0083] Table 2 Ionic conductivity (S / cm)

[0084] As can be seen from Table 2, the ionic conductivities of Examples 6-8 of the present invention are higher than those of Example 5. This is because, in the preparation of the poly(1,3-dioxolane)-based composite electrolyte, Examples 6-8 introduce functional agents, which include succinonitrile, vanillyl alcohol ethyl ether, and dihydromyrcenol. The ionic conductivity of Example 6 is higher than that of Examples 7 and 8. This is because, in the preparation of the poly(1,3-dioxolane)-based composite electrolyte, the amounts of vanillyl alcohol ethyl ether and dihydromyrcenol used are different. The ionic conductivity of Example 6 is higher than that of Comparative Examples 2 and 3. This is because, in the preparation of the poly(1,3-dioxolane)-based composite electrolyte, Example 5 uses vanillyl alcohol ethyl ether and dihydromyrcenol in combination, while Comparative Example 2 uses vanillyl alcohol ethyl ether alone, and Comparative Example 3 uses dihydromyrcenol alone. This shows that compared with the use of vanillyl alcohol ethyl ether and dihydromyrcenol alone, the synergistic use of vanillyl alcohol ethyl ether and dihydromyrcenol as functional agents can effectively improve the ionic conductivity of the prepared poly (1,3-dioxolane) based composite electrolyte.

[0085] The ionic conductivity of Examples 9-10 of the present invention is higher than that of Example 6 because, in the preparation of the poly(1,3-dioxolane)-based composite electrolyte, Examples 9-10 further introduce propylene glycol methyl ether propionate into the functional agent. The ionic conductivity of Example 9 is higher than that of Example 10 because the amount of propylene glycol methyl ether propionate used in the preparation of the poly(1,3-dioxolane)-based composite electrolyte is different. The ionic conductivity of Example 9 is higher than that of Comparative Example 4 because, in the preparation of the poly(1,3-dioxolane)-based composite electrolyte, Comparative Example 5 uses propylene glycol methyl ether propionate alone without vanillyl alcohol ethyl ether and dihydromyrcenol. This indicates that further introducing propylene glycol methyl ether propionate into the functional agent in the preparation of the poly(1,3-dioxolane)-based composite electrolyte can further improve the ionic conductivity of the prepared poly(1,3-dioxolane)-based composite electrolyte.

[0086] The conventional operations in the operating steps of the present invention are well known to those skilled in the art and will not be described in detail here.

[0087] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any changes and modifications made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a poly(1,3-dioxolane)-based composite electrolyte, comprising: adding a sodium salt and a 1,3-dioxolane monomer to a solvent, and then mixing with an additive to obtain a precursor; then allowing the precursor to stand at room temperature, and heating to initiate polymerization and curing of the precursor to obtain the poly(1,3-dioxolane)-based composite electrolyte; the additive comprises a crosslinker and / or an inorganic filler, wherein the crosslinker is trimethylolpropane triglycidyl ether, and the inorganic filler is a NASICON solid electrolyte powder; the volume of the crosslinker is equivalent to 1.5-3% of the volume of the 1,3-dioxolane monomer, and the mass of the inorganic filler is equivalent to 1.5-3% by weight of the volume of the 1,3-dioxolane monomer.

2. The method for preparing a poly (1,3-dioxolane) based composite electrolyte according to claim 1, characterized in that: The mass of the sodium salt is equivalent to 4-8 wt % of the volume of the 1,3-dioxolane monomer.

3. The method for preparing a poly (1,3-dioxolane) based composite electrolyte according to claim 1, characterized in that: The sodium salt includes at least one of sodium hexafluorophosphate and sodium bis(trifluoromethanesulfonyl)imide.

4. The method for preparing a poly (1,3-dioxolane) based composite electrolyte according to claim 1, characterized in that: The volume of the solvent is equivalent to 20-70% of the volume of the 1,3-dioxolane monomer.

5. The method for preparing a poly (1,3-dioxolane) based composite electrolyte according to claim 1, characterized in that: The solvents include sodium hexafluorophosphate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate and fluoroethylene carbonate.

6. The method for preparing a poly (1,3-dioxolane) based composite electrolyte according to claim 1, characterized in that: The polymerization curing temperature is 50-60° C., and the polymerization curing time is 3-15 hours.

7. The method for preparing a poly (1,3-dioxolane) based composite electrolyte according to claim 1, characterized in that: The additives also include functional agents.

8. The method for preparing a poly (1,3-dioxolane) based composite electrolyte according to claim 7, characterized in that: The functional agent includes succinonitrile, vanillyl alcohol ethyl ether and dihydromyrcenol.

9. The method for preparing a poly (1,3-dioxolane) based composite electrolyte according to claim 8, characterized in that: The mass of the vanillyl alcohol ether is equivalent to 10-20 wt % of the volume of succinonitrile.

10. The method for preparing a poly (1,3-dioxolane) based composite electrolyte according to claim 8, characterized in that: The volume of the dihydromyrcenol is equivalent to 8-15% of the volume of succinonitrile.

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