CN-122025769-A - Sodium-based ionic eutectic solid electrolyte and application thereof in high-performance sodium metal battery

CN122025769ACN 122025769 ACN122025769 ACN 122025769ACN-122025769-A

Abstract

The application discloses a sodium-based ionic eutectic solid electrolyte and application thereof in a high-performance sodium metal battery, and belongs to the field of electrochemical energy storage, wherein the electrolyte is formed by co-crystallizing sodium perchlorate and succinonitrile according to a molar ratio of 1:2.6-3.2, an ordered-unordered coexisting crystal structure is constructed on a molecular scale, na + and part of SN molecules and ClO 4 ‑ occupy regular coordination skeleton sites respectively, extra SN molecules fill lattice gaps in an unordered orientation manner, a continuous three-dimensional sodium ion transmission channel is established, anions are effectively fixed, naClO 4 (SN) x can be subjected to in-situ melting-infiltration-resolidification after the battery is assembled, electrode pores and interface gaps are fully filled, interface impedance is reduced, the cooperative optimization of ion migration efficiency and interface compatibility is realized through an eutectic structure design and an in-situ melting process, a solid electrolyte solution is provided for safe and efficient operation of the sodium metal battery, and the solid electrolyte has wide application prospect.

Inventors

JIN ZHONG
YANG BINZE
XING YIZHI
WEN SHENG
You Zhihu
LIU XUAN
WANG JINGYI
TIE ZUOXIU

Assignees

南京大学天长新材料与能源技术研发中心
南京大学
天长索锂德新能源科技有限公司
苏州铁睿新能源科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260122

Claims (10)

1. A sodium-based ionic eutectic solid electrolyte is characterized in that sodium perchlorate NaClO 4 and succinonitrile SN are co-crystallized according to a molar ratio of 1:2.6-3.2 to form a single-phase solid, an ordered-unordered concurrent crystal network is constructed on a lattice scale to provide a continuous three-dimensional sodium ion transmission migration channel, and the sodium-based ionic eutectic solid electrolyte is NaClO 4 (SN) x , wherein x=2.6-3.2.
2. The sodium-based ionic eutectic solid electrolyte of claim 1, wherein the molar ratio of NaClO 4 to SN is between 12.95 and 3.05.
3. The sodium-based ionic eutectic solid state electrolyte of claim 1, wherein Na + occupies octahedral sites, clO 4 - occupies tetrahedral sites, and SN molecules fill the lattice gaps in an unordered orientation, thereby forming vertex-to-vertex connected ion migration channels within the lattice.
4. The method for preparing the sodium-based ionic eutectic solid electrolyte in the high-performance sodium metal battery, which is characterized in that the sodium-based ionic eutectic solid electrolyte is used as the electrolyte of the high-performance sodium metal battery, the negative electrode is a metal sodium or sodium-containing composite negative electrode, and the positive electrode is one or more of layered oxides, polyanion compounds, prussian blue and organic positive electrode materials.
5. The use of a sodium-based ionic eutectic solid electrolyte in a high-performance sodium metal battery according to claim 4, wherein the positive electrode is one of Na 3 V 2 (PO 4 ) 3 、Na 3 V 2 (PO 4 ) 2 F 3 , prussian blue/Prussian white, sodium ferric sulfate or an organic positive electrode containing a carbonyl coordination structure, and the NaClO 4 (SN) 3 eutectic electrolyte exists between the electrodes in a solid or near solid state form filling the pores of the electrodes and the separator, and the equivalent thickness between the electrodes is 10-200 μm.
6. The use of a sodium-based ionic eutectic solid state electrolyte in a high performance sodium metal battery according to claim 4, wherein the method for in situ construction of the sodium-based eutectic solid state electrolyte in a sodium metal battery comprises the steps of: Step 1, raw material proportioning and pretreatment, namely weighing NaClO 4 and SN raw materials according to the molar ratio of NaClO 4 to SN=1 to (2.6-3.2), uniformly mixing in an inert atmosphere glove box or a dry environment, and avoiding the introduction of damp and impurities to obtain a NaClO 4 /SN precursor mixture for in-situ melting; Step 2, preassembling a dry cell, namely preparing a positive electrode by selecting one or more of layered oxides, polyanion compounds, prussian blue and organic positive electrode materials according to a target system, preparing a negative electrode by using porous diaphragm metal sodium or sodium-containing composite negative electrode, stacking the positive electrode, the diaphragm and the negative electrode into a battery shell according to the sequence of the positive electrode, the diaphragm and the negative electrode in an inert atmosphere, presetting a NaClO 4 /SN precursor mixture between the diaphragm and the positive electrode, between the diaphragm and the negative electrode or in an independent liquid storage cavity to form a dry cell structure, wherein the diaphragm is a porous diaphragm; Heating the assembled dry battery cell to 60-120 ℃ in inert atmosphere for 10-120 min, melting NaClO 4 /SN precursor mixture into uniform transparent melt, keeping 60-120 ℃ to enable the melt to infiltrate the porous structures of the anode, the diaphragm and the cathode in situ by virtue of capillary action, filling the pores and the interface gaps of the electrode, and completing the spatial distribution and component homogenization of the electrolyte in the battery cell; And 4, cooling the melted and infiltrated battery core in an inert atmosphere at a cooling rate of 0.1-10 ℃ min -1 to cool the battery core to room temperature, so that the NaClO 4 and the SN are subjected to eutectic crystallization in the battery to form a continuous compact NaClO 4 (SN) x eutectic solid electrolyte network which is free of obvious macroscopic cracks and relatively single-phase, in-situ filling and fixing of the electrode and the membrane pore channel are realized, a self-supporting electrolyte membrane is not required to be independently prepared, and free SN is not required to be intentionally removed in a deep vacuumizing mode.
7. The method of claim 6, wherein in step 3, the melt is more fully infiltrated into the pores of the positive electrode, the separator and the negative electrode by vacuum assistance or pulse pressurization, so as to increase the contact area between the electrolyte and the electrode, and in step 4, the stabilizing annealing is performed at 40-80 ℃ to further perfect the crystal structure and the interface microstructure.
8. The use of a sodium-based ionic eutectic solid electrolyte in a high performance sodium metal battery according to claim 6, wherein steps 2-4 are integrally completed in the same cell by preassembling a dry cell and introducing a NaClO 4 /SN precursor mixture, and synchronously constructing in-situ interface coupling of the electrolyte and the pole piece during the heating melting-in-situ infiltration-cooling crystallization process, thereby obtaining an electrode-electrolyte interface which has low interface impedance, is in close contact and is not easy to delaminate during the cycling process.
9. The method for assembling a sodium-based ionic eutectic solid electrolyte in a high-performance sodium metal battery according to claim 4, wherein the sodium-based ionic eutectic solid electrolyte comprises the steps of selecting one or more of layered oxides, polyanion compounds, prussian blue and organic positive electrodes to prepare a positive electrode plate, pre-assembling the positive electrode plate with a porous diaphragm and a metal sodium or sodium-containing composite negative electrode in an inert atmosphere to form a dry cell, injecting a NaClO 4 /SN precursor mixture prepared according to NaClO 4 :SN=1: (2.8-3.2) into the dry cell, in-situ melting and infiltrating at 60-120 ℃ and cooling and crystallizing, in-situ forming a NaClO 4 (SN) x eutectic solid electrolyte layer with an equivalent thickness of 10-200 mu m between the positive electrode and the negative electrode, completing lamination and sealing packaging, and constructing a Na symmetrical battery by the in-situ melting-crystallizing strategy for evaluating interface stability and long-cycle reversible deposition/stripping.
10. The use of a sodium-based ionic eutectic solid state electrolyte in a high performance sodium metal battery according to claim 9, wherein the in-situ melt infiltration-cooling crystallization mode forms an electrolyte layer in Na structure, achieves reversible deposition/stripping behavior with stable polarization voltage of 100 mV or less at a current density of 0.1-1 mA cm -2 , and does not occur short circuit or polarization surge during continuous cycling of 500 or more h.

Description

Sodium-based ionic eutectic solid electrolyte and application thereof in high-performance sodium metal battery Technical Field The application relates to the technical field of electrochemical energy storage, in particular to a sodium-based ionic eutectic solid electrolyte and application thereof in a high-performance sodium metal battery. Background With the promotion of large-scale renewable energy grid connection and high-safety energy storage demands, sodium metal batteries are widely focused on due to resource availability and cost advantages. However, the conventional liquid electrolyte has the problems of inflammable leakage, unstable interface, dendrite growth and the like, so that the cycle life and safety are limited, and the polymer or ceramic solid electrolyte can improve the safety level, but is often influenced by insufficient ion conductivity at room temperature, poor interface contact and concentration polarization induced by anion migration. In order to achieve both high ion conduction and interface compatibility, the invention provides NaClO 4(SN)x eutectic solid electrolyte formed by co-crystallizing NaClO 4 and succinonitrile according to a specific molar ratio, wherein a continuous three-dimensional sodium ion migration channel is constructed in a crystal lattice by utilizing an ordered-unordered coexisting crystal skeleton, na + and ClO 4- occupy lattice skeleton sites, SN molecules fill gaps in an unordered manner in an orientation manner, and the synergy of an ion conduction network and mechanical compliance is realized. Disclosure of Invention The application provides a sodium-based ionic eutectic solid electrolyte and application thereof in a high-performance sodium metal battery, and aims to solve the technical problems that in the prior art, when the sodium metal battery adopts an organic liquid electrolyte, inflammable leakage, poor safety, narrow working temperature window and the traditional polymer/inorganic solid electrolyte has low room-temperature ionic conductivity, insufficient migration number of Na +, incontrollable dendrite growth caused by poor contact with a sodium metal interface, continuous increase of interface impedance, difficulty in considering high-voltage positive electrode matching and cycling stability and the like are solved by taking NaClO 4(SN)3 and other ordered-unordered hybrid ionic eutectic solid electrolytes as cores. The technical scheme of the invention is as follows: The sodium-based ionic eutectic solid electrolyte is characterized in that sodium perchlorate NaClO 4 and succinonitrile SN are co-crystallized according to a molar ratio of 1:2.6-3.2 to form a single-phase solid, an ordered-unordered concurrent crystal network is constructed on a lattice scale to provide a continuous three-dimensional sodium ion transmission migration channel, and the sodium-based ionic eutectic solid electrolyte is NaClO 4(SN)x, wherein x=2.6-3.2. Further, the molar ratio of NaClO 4 to SN is 12.95-3.05. Further, na + occupies octahedral sites in the crystal, clO 4- occupies tetrahedral sites, and SN molecules fill lattice gaps in a disordered orientation manner, so that ion migration channels with vertex-vertex connectivity are formed in the lattice. Further, the ionic conductivity at 25 ℃ is more than or equal to 1 multiplied by 10 -4 S·cm-1, the migration number of sodium ions is more than or equal to 0.9, the electrochemical stability window relative to Na +/Na is more than or equal to 4.5V, preferably more than or equal to 4.6V, the reversible ordered-disordered transition is realized within the range of 30-120 ℃, the continuous ion transmission network and the mechanical integrity are maintained, and the ionic transmission network can be matched with a metal sodium negative electrode and a plurality of positive electrode materials in a synergistic way. The application also discloses application of any one of the ionic eutectic solid electrolyte in a high-performance sodium metal battery, wherein the sodium-based ionic eutectic solid electrolyte is used as the electrolyte of the high-performance sodium metal battery, the negative electrode is a metal sodium or sodium-containing composite negative electrode, and the positive electrode is one or more of layered oxide, polyanion compounds, prussian blue and organic positive electrode materials. Further, the positive electrode is one of Na 3V2(PO4)3、Na3V2(PO4)2F3, prussian blue/Prussian white, ferric sodium sulfate or an organic positive electrode containing a carbonyl coordination structure, the NaClO 4(SN)3 eutectic electrolyte exists between the electrodes in a solid or near-solid state form for filling the pores of the electrodes and the diaphragm, and the equivalent thickness between the electrodes is 10-200 mu m. Further, the high-performance sodium metal battery maintains coulombic efficiency of more than or equal to 99.0% under the current density of more than or equal to 1mA cm -2, and maintains a stable