Ion-doped modified lithium-zirconium-silicon-phosphorus-oxygen solid-state electrolyte, preparation and application thereof

Abstract

The present application relates to the technical field of solid-state lithium ion batteries, and particularly relates to a lithium-zirconium-silicon-phosphorus-oxygen solid electrolyte prepared by ion doping modification, which can be used for manufacturing full solid-state lithium secondary batteries. 3‑x+y Zr 2‑x Nb x Si 2‑y Ga y PO 12 (0≤y≤x≤1 and x≠0). The ion doping modified lithium-zirconium-silicon-phosphorus-oxygen solid electrolyte prepared by the present application has good mechanical properties, excellent ionic conductivity and better electrochemical stability; can be used as an ideal solid electrolyte material in full solid-state lithium ion secondary batteries, and the preparation method is environmentally friendly and energy-saving, and is suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the technical field of solid-state lithium-ion batteries, specifically to a lithium zirconium silicon phosphorus oxygen solid electrolyte prepared by ion doping modification, which can be used to manufacture all-solid-state lithium secondary batteries. Background Technology

[0002] To meet the development trend of environmentally friendly, high-energy-density electricity, lithium-ion batteries (LIBs) have emerged. Currently, traditional liquid lithium-ion batteries are widely used due to their high ionic conductivity and good interfacial contact, thanks to their rich organic liquid electrolyte. However, problems such as low lithium-ion transference number, easy leakage, high volatility, and strong flammability have seriously hindered the further development of liquid lithium-ion batteries.

[0003] All-solid-state batteries (ASSBs) offer advantages such as low leakage risk, low flammability, and high energy density, addressing many of the problems associated with current liquid lithium-ion batteries. Furthermore, ASBs possess a wide chemical window and a highly stable electrochemical interface. Therefore, replacing organic liquid electrolytes with solid electrolytes is the optimal choice for optimizing energy density and improving safety.

[0004] To date, different types of inorganic fast lithium-ion solid electrolytes such as Li-βˊˊ-Ga2O3, sulfides (Li3PS4, Li2S-P2S5, Li 10 SnP2S 12 Lithium superionic conductor (LISICON) Li 1+x Zr2Si x P 3-x O 12 (0≤) x ≤3) All of these have been developed for use in solid-state lithium-ion batteries. Among them, Li-βˊˊ-Ga2O3 is widely used in Li-S batteries; however, Li-βˊˊ-Ga2O3 is very sensitive to moisture and often requires a high sintering temperature (about 1600℃), which limits its application range. In addition, although sulfide-based solid electrolytes have high ionic conductivity and good ductility, most are unstable in air and exhibit a narrow electrochemical stability window.

[0005] Lithium superionic conductor (LISICON) Li 1+x Zr2Si x P 3-x O 12 Compared to other lithium-ion solid electrolytes, Li₂ exhibits high ionic conductivity, a broad electrochemical stability window, and good atmospheric stability. These characteristics have attracted widespread attention and led to extensive research. However, currently produced Li₂... 1+xZr2Si x P 3-x O 12 Its ionic conductivity is still inferior to that of liquid electrolytes, and there is still room for improvement. Summary of the Invention

[0006] This invention aims to overcome the limitations of existing lithium superionic conductors (Li). 1+x Zr2Si x P 3-x O 12 To address the drawback of low ionic conductivity, this paper presents an ion-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte, along with its preparation and application, to overcome this deficiency.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] An ion-doped modified lithium-zirconium-silicon-phosphorus-oxygen solid electrolyte is disclosed. This ion-doped modified lithium-zirconium-silicon-phosphorus-oxygen solid electrolyte is prepared by a one-step sol-gel method, in which a niobium source or a niobium-gallium source is added to a mixed solution used in the preparation of the lithium-zirconium-silicon-phosphorus-oxygen solid electrolyte. Its general formula is Li 3-x+y Zr 2-x Nb x Si 2-y Ga y PO 12 (0≤y≤x≤1 and x≠0).

[0009] To further improve the ionic conductivity of lithium zirconium silicon phosphorus oxygen solid electrolyte, the inventors of this application propose to increase the vacancy rate within the lithium zirconium silicon phosphorus oxygen solid electrolyte by ion doping modification.

[0010] The first approach is to introduce niobium into the preparation process of lithium zirconium silicon phosphorus oxygen solid electrolyte, using Nb... 5+ Zr replacing lithium zirconium silicon phosphorus oxygen solid electrolyte 4+ Nb 5+ Replace Zr in LZSP 4+ This is an unequal substitution; when a higher valence ion replaces a lower valence ion, an imbalance of charge is created during the substitution process. When the charge accumulates near the substitution site, a Li vacancy is created at the original site. Furthermore, due to the substitution ion (Nb... 5+ The ionic radius of the ion is 0.69 Å, and the radius of the substituted ion (Zr) is... 4+ Similar to the ionic radius of 0.72 Å, it has almost no effect on other sites, only causing changes in Li vacancies due to non-equivalent substitution. However, the solid electrolyte generates Li vacancies, significantly altering its internal Li... + Distribution, thereby increasing Li + The jump rate increases the ionic conductivity.

[0011] The second approach involves introducing niobium and gallium elements during the preparation of the lithium zirconium silicon phosphorus oxygen solid electrolyte, with Nb as the primary element. 5+ Zr replacing lithium zirconium silicon phosphorus oxygen solid electrolyte 4+ Ga 3+ Si replacing lithium zirconium silicon phosphorus oxygen solid electrolyte 4+ Site. The advantage of introducing more gallium elements through niobium-gallium co-doping to improve ionic conductivity is that, in Nb... 5+ Zr replacing lithium zirconium silicon phosphorus oxygen solid electrolyte 4+ After generating a large number of Li vacancies, Ga can also be used. 3+ Replace Si 4+ The concentration of Li vacancies can be adjusted by using site-specific methods.

[0012] Current research has explored solutions that use Ga to replace Li to achieve performance optimization. However, in this application, the inventors have discovered that Ga… 3+ Compared to Li + In terms of Si 4+ The price state difference is smaller, therefore Ga 3+ Easier to replace Si 4+ Instead of Li + After substitution, it is easier to reach equilibrium, which can ensure the basic structure of the solid electrolyte itself before and after ion substitution, thereby ensuring that the material purity of the solid electrolyte can still be maintained at a high level after ion doping.

[0013] Nb 5+ Zr replacing lithium zirconium silicon phosphorus oxygen solid electrolyte 4+ This is an unequal substitution; when a higher valence molecule replaces a lower valence molecule, an imbalance of charge is created during the substitution process. When the charge accumulates near the substitution site, a Li vacancy is created at the original site. Subsequently, Ga... 3+ Replace Si 4+ The lower valence ion replaces the higher valence ion, thereby balancing part of the charge imbalance and adjusting the Li vacancy concentration. This allows the doped solid electrolyte to maintain the optimal Li vacancy concentration, resulting in higher ionic conductivity.

[0014] Both schemes proposed in this invention involve non-equivalent cation substitution doping, which has the advantage of generating vacancies or increasing lithium ion concentration, thereby improving the conductivity of solid electrolytes, and the method is simpler and faster.

[0015] To verify that the lithium zirconium silicon phosphorus oxygen solid electrolyte obtained by implementing the scheme proposed in this invention has improved ionic conductivity, the inventors conducted relevant performance tests.

[0016] XRD test results show that the lithium zirconium silicon phosphorus oxygen solid electrolytes prepared by niobium doping and niobium-gallium co-doping modification are all pure-phase lithium zirconium silicon phosphorus oxygen solid electrolytes in the XRD images. Their XRD patterns are consistent with the diffraction peaks of the standard card and no impurity phases are generated.

[0017] Electrochemical performance test results show that the ionic conductivity of the niobium-doped lithium zirconium silicon phosphorus oxygen solid electrolyte is 1.97*10 compared to the undoped lithium zirconium silicon phosphorus oxygen solid electrolyte. -3 S / cm increased to 4.7*10 -3 The discharge capacity at 0.1C for 100 cycles (S / cm) increased from 451.2 mAh / g to 548.5 mAh / g.

[0018] The ionic conductivity of the niobium-gallium co-doped lithium zirconium silicon phosphorus oxygen solid electrolyte, compared to the undoped lithium zirconium silicon phosphorus oxygen solid electrolyte, is increased from 1.97*10. -3 S / cm increased to 6.2*10 -3 S / cm, the discharge capacity at 0.1C for 100 cycles increased from 451.2 mAh / g to 648.7 mAh / g.

[0019] It is worth noting that niobium-gallium co-doping exhibits better results than niobium single doping. The lithium zirconium silicon phosphorus oxygen solid electrolyte modified by niobium-gallium co-doping exhibits higher ionic conductivity and greater discharge capacity.

[0020] A method for preparing an ion-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte includes the following steps:

[0021] S1. Add the silicon source and the first doped metal source to an ethanol-water solution and mix. Add a complexing agent and adjust the pH of the solution to 1-3 with an inorganic acid to obtain solution A.

[0022] S2. Add the lithium source, the second doped metal source, and the zirconium source to water and mix to obtain solution B;

[0023] S3. Add oxygen source and phosphorus source to water and mix to obtain solution C;

[0024] S4. Mix solutions A, B, and C and dry them in an oven until a dry gel is formed;

[0025] S5. After repeating the pulverization and calcination steps of the dry gel at least twice, the general formula Li is obtained. 3-x+y Zr 2-x Nb x Si 2- y Ga y PO 12(0≤y≤x≤1 and x≠0) Ion-doped modified lithium zirconium silicon phosphorus oxygen type solid electrolyte material;

[0026] The first doped metal source is selected from either a niobium source or a gallium source, and the second doped metal source is selected from either a gallium source or a niobium source.

[0027] The inventors of this application, based on the traditional preparation of lithium zirconium silicon phosphorus oxygen solid electrolyte, added a niobium source or niobium gallium source in the early solution mixing stage, and then prepared the ion-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte by a one-step sol-gel method.

[0028] In this process, the niobium source and the gallium source can be arbitrarily selected and mixed with the solutions in S1 or S2. Dissolving each source separately before mixing ensures the subsequent reaction proceeds fully. Secondly, the gallium source can be omitted. When the amount of gallium source added is 0: the resulting reaction formula is Li... 3-x+y Zr 2-x Nb x Si 2-y Ga y PO 12 In the condition (0≤y≤x≤1 and x≠0), y=0. This constitutes two solutions of the present invention: 1) a niobium ion-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte, and 2) a niobium ion and gallium ion co-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte.

[0029] Furthermore, this scheme employs a sol-gel method to simultaneously complete the doping modification and preparation of lithium zirconium silicon phosphorus oxygen solid electrolyte. First, the various source solutions are mixed and dried to obtain a dry gel. However, since the dry gel contains moisture, it is pre-calcined to remove this moisture before formal sintering. This approach has the advantage of preventing powder agglomeration and making it easier to handle. Additionally, calcining the dry gel multiple times lowers the overall sintering temperature. Generally, pre-calcination followed by calcination yields the modified lithium zirconium silicon phosphorus oxygen solid electrolyte powder. A third calcination helps to further refine the powder, making it easier to obtain nano-sized lithium zirconium silicon phosphorus oxygen solid electrolyte powder.

[0030] Before the pre-calcination step or before calcination, the powder is pulverized and refined to help the moisture evaporate quickly. At the same time, as the moisture evaporates or calcination proceeds, the powder is less likely to agglomerate, thus maintaining a powder material with good morphology and small and uniform particle size.

[0031] The calcination process is a reaction that removes oxygen, hydrogen, nitrogen, and other elements, allowing the compound to recombine and generate a new compound. In this process, the substituted element moves into the position of the substituted element, thus achieving the purpose of substitution.

[0032] Therefore, the first aspect of the present invention is to use Nb 5+(Ionic radius 0.69 Å) Zr replacing Zr in lithium zirconium silicon phosphorus oxygen solid electrolyte 4+ (Ionic radius 0.72 Å) can generate more Li vacancies during calcination, reducing grain boundary resistance and increasing ionic conductivity. Simultaneously, the addition of Nb can also significantly alter the Li... + The distribution of Li increases + The jump rate.

[0033] However, during the implementation of the above scheme, an excess of Li vacancies may occur, leading to a decrease in the mobility of Li. + The concentration is reduced, thereby suppressing the increase in ionic conductivity.

[0034] Subsequently, the second aspect of the present invention is based on the first aspect, using trivalent metal cation Ga. 3+ (Ionic radius 0.62 Å) Substituted tetravalent Si 4+ (Ionic radius 0.4 Å). In Zr 4+ Site and Si 4+ Inequivalent cation substitution doping at sites can tune the optimal Li vacancy concentration to improve ionic conductivity. Among these, Ga... 3+ and Si 4+ The ionic radii of the two molecules are relatively close, and their valence states are similar, making them easy to substitute.

[0035] Preferably, the gallium source is selected from gallium acetate, gallium nitrate, gallium sulfate, gallium citrate, and gallium carbonate, and the niobium source is selected from niobium nitrate, niobium sulfate, niobium carbonate, niobium acetate, and niobium chloride.

[0036] This invention designs Nb 5+ Zr replacing lithium zirconium silicon phosphorus oxide 4+ Site, Ga 3+ Si in lithium zirconium silicon phosphorus oxide 4+ The required niobium and gallium sources only need to provide monovalent niobium ions and trivalent gallium ions.

[0037] Preferably, the silicon source is selected from tetraethyl orthosilicate or tetraethyl orthosilicate.

[0038] Preferably, the complexing agent is selected from one or more of citric acid, ammonium citrate, maleic acid, oxalic acid, ammonium oxalate, ascorbic acid, and sodium ethylenediaminetetraacetate.

[0039] The role of complexing agents in solid electrolytes is to improve the ion transport performance and chemical stability of the electrolyte.

[0040] Solid electrolytes typically suffer from insufficient ionic conductivity due to the regularity of their crystal lattice, necessitating the addition of complexing agents to improve ionic conductivity. Complexing agents can undergo strong coordination reactions with metal ions, thereby encapsulating the metal ions within the metastable structure of their complexes, forming a bridging structure. In this way, because complexing agents enhance cation transport, they improve the ion transport performance of the electrolyte.

[0041] In addition, complexing agents are also very important for improving the chemical stability of solid electrolytes.

[0042] Taking citric acid as an example: Citric acid, namely 2-hydroxy-1,2,3-hexamethylenetriacid, can theoretically ionize to form three protons, resulting in three -COO- coordination functional groups, plus one -OH group, making it a tetradentate ligand. It can form multiple five-membered chelate ring stereocoagulation structures depending on the situation. Chelated coordination complexes with five- and six-membered ring structures generally have high stability. For stability considerations, the complexing agents selected in this application are all multi-component chelates.

[0043] During battery cycling, the electrolyte is often subjected to electrochemical reactions, therefore its chemical stability has a decisive impact on the battery's cycle life. The addition of a complexing agent can prevent the entry of impurity ions from the electrolyte and the dissolution of the metal electrodes in the battery, ensuring the stability and durability of the solid electrolyte.

[0044] Preferably, the inorganic acid is selected from one or more of nitric acid, hydrochloric acid, and sulfuric acid.

[0045] More preferably, after adjustment with inorganic acid, the pH of the solution is 1 to 1.5.

[0046] In a strongly acidic environment, complete dissolution of lithium ions and other metal ions can be ensured, preventing precipitation during the dissolution of raw materials. Simultaneously, a low pH value leads to an increase in the number of cations in the dielectric, reducing the diffusion path of lithium ions in the solid electrolyte, increasing the ion transport number, and improving the electrochemical performance of the solid electrolyte material. To ensure sufficient ion dissolution, a pH range of 1–1.5 is preferred.

[0047] Preferably, the lithium source is selected from one of lithium nitrate, lithium sulfate, lithium carbonate, lithium acetate, and lithium chloride.

[0048] Preferably, the zirconium source is selected from one of zirconium nitrate, zirconium sulfate, zirconium carbonate, zirconium acetate, and zirconium chloride.

[0049] Preferably, the lithium source needs to be in excess by 5-10 wt%.

[0050] Lithium sources are easily lost through volatilization during sintering, so an excess of 5-10% of its own mass is required.

[0051] Preferably, both the oxygen source and the phosphorus source are derived from ammonium dihydrogen phosphate or diammonium hydrogen phosphate.

[0052] Preferably, the drying temperature of the dry gel is 120~150℃.

[0053] Drying at 120-150℃ for 10-15 hours in a forced-air drying oven or a vacuum drying oven can essentially evaporate the solution to form a dry gel. The drying temperature in a forced-air drying oven can be slightly lower than that in a vacuum drying oven, while the advantage of a vacuum drying oven is that it helps to form powder materials with better morphology.

[0054] Preferably, the calcination temperature after the first crushing is 300-400℃; the calcination temperature after the second and subsequent crushings is 1100-1300℃.

[0055] Materials prepared by the sol-gel method contain a high proportion of organic matter and volatile components such as water. Pre-sintering can volatilize these components, achieving the purpose of material pretreatment, reducing organic matter content, and improving the thermal stability of the material.

[0056] If the moisture in the dry gel is not completely removed, direct calcination will result in an overly hard, agglomerated final product that is difficult to handle. Pre-calcined powder, on the other hand, is less prone to agglomeration and easier to process. Furthermore, calcining the dry gel multiple times can lower the overall sintering temperature, reducing the requirements for sintering equipment and broadening the practical application range of this solution.

[0057] In addition, ball milling is usually used to pulverize and refine the powder. Ball milling at 550~750 rpm for 5~8 hours can obtain uniform powder with small particle size. After pre-calcination, ball milling, recalcination, ball milling, and a third calcination can basically obtain solid electrolyte powder with nano-sized particles.

[0058] More preferably, the heating rate during calcination is 1–3 °C / min.

[0059] Excessively high or low heating rates will affect the stability and particle uniformity of the solid electrolyte obtained after calcination. To ensure high stability and high particle uniformity of the synthesized material, the inventors of this application have discovered that controlling the heating rate during calcination at 1~3 ℃ / min can ensure that the calcined material has good stability and high particle uniformity.

[0060] The ion-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte prepared by this method can be used to manufacture all-solid-state lithium secondary batteries.

[0061] With Nb 5+ Zr replacing lithium zirconium silicon phosphorus oxygen solid electrolyte 4+ Site, or Nb 5+Zr replacing lithium zirconium silicon phosphorus oxygen solid electrolyte 4+ Site and Ga 3+ Si replaces lithium zirconium silicon phosphorus oxygen solid electrolyte 4+ A site-specific method was used to prepare an ion-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte. The modified solid electrolyte exhibits significantly improved ionic conductivity and can be applied to all-solid-state lithium secondary batteries. In practical applications, batteries made with high-ionic-conductivity solid electrolytes have higher energy density, faster charging speeds, and longer cycle life. Therefore, the ion-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte proposed in this invention has significant practical value.

[0062] Therefore, the present invention has the following beneficial effects:

[0063] (1) This invention proposes Nb 5+ Zr replacing lithium zirconium silicon phosphorus oxygen solid electrolyte 4+ These sites can help solid electrolytes generate Li vacancies, reduce grain boundary resistance, and improve ionic conductivity.

[0064] (2) The Ga proposed in this invention 3+ Si replaces lithium zirconium silicon phosphorus oxygen solid electrolyte 4+ Site-assisted Nb 5+ Zr replacing lithium zirconium silicon phosphorus oxygen solid electrolyte 4+ Site, Ga 3+ The addition of Nb can solve 5+ The addition of ions helps address the potential problem of excessive Li vacancies leading to a decrease in the concentration of mobile Li+ ions, thus improving the internal Li+ concentration of the ion-doped solid electrolyte. + Maintain the concentration at the optimal level to ensure high ionic conductivity;

[0065] (3) The ion-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte material proposed in this invention is synthesized by a one-step sol-gel method. The heat treatment stage of the sol-gel is completed by pre-sintering and calcination or multiple calcinations. Therefore, the required sintering temperature is lower, the requirements for sintering equipment are lower, and it is more suitable for widespread production and cost reduction manufacturing.

[0066] (4) The ion-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte prepared by the present invention has good mechanical properties, excellent ionic conductivity and good electrochemical stability.

[0067] (5) The ion-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte material prepared by the present invention can be used as an ideal solid electrolyte material in all-solid-state lithium-ion secondary batteries. Its preparation method is environmentally friendly and energy-saving, and is suitable for large-scale production. Attached Figure Description

[0068] Figure 1For Li 3-x+y Zr 2-x Nb x Si 2-y Ga y PO 12 A series of X-ray diffraction comparison images of solid electrolyte powders. Detailed Implementation

[0069] The present invention will be further described below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0070]

Example

[0071] Example 1

[0072] (1) According to the general formula: Li 2.9 Zr 1.9 Nb 0.1 Si2PO 12 Weigh 20 g of tetraethyl orthosilicate (Si(C2H5O)4) and add 100 mL of an aqueous ethanol solution, wherein the volume ratio of ethanol to water is 1:1. Then add 20 g of an aqueous citric acid solution and adjust the pH of the solution to 1 with 67% nitric acid to obtain solution A.

[0073] (2) 3.72 g lithium nitrate (LiNO3), 0.28 g niobium nitrate (Nb(NO3)5·5H2O) and 8.42 g zirconium nitrate (ZrO(NO3)2·5H2O) were added to 25 mL of deionized water and mixed evenly to obtain solution B.

[0074] (3) Add 4.31 g of diammonium hydrogen phosphate ((NH4)2HPO4) to 25 mL of deionized water to form a homogeneous solution, and obtain solution C.

[0075] (4) Mix the above three solutions A, B and C and evaporate them in a vacuum oven at 125°C for 12 h to form a dry gel.

[0076] (5) After ball milling the dry gel once, it was transferred to a muffle furnace and pre-fired at 350°C for 8 hours to obtain the pre-fired block.

[0077] (6) The pre-burned block obtained in step (5) is subjected to secondary ball milling to obtain secondary powder.

[0078] (7) Sinter the secondary powder obtained in step (6) at 1200℃ for 8 h.

[0079] (8) After the reaction is complete, the mixture is allowed to cool naturally to room temperature to obtain a product with the composition Li. 2.9 Zr 1.9 Nb 0.1 Si2PO 12 Niobium ion-doped modified lithium zirconium silicon phosphorus oxide solid electrolyte (LZNSP) material. To obtain nano-LZNSP, the obtained powder is milled using high-energy ball milling and then sintered at 1200℃ for 6 h.

[0080] Example 2

[0081] (1) According to the general formula: Li 2.8 Zr 1.8 Nb 0.2 Si2PO 12 Weigh 20 g of tetraethyl orthosilicate (Si(C2H5O)4) and add it to 100 mL of an aqueous ethanol solution, wherein the volume ratio of ethanol to water is 1:1. Then add 20 g of an aqueous citric acid solution and adjust the pH of the solution to 1.3 with 67% nitric acid to obtain solution A.

[0082] (2) 3.68 g lithium nitrate (LiNO3), 0.56 g niobium nitrate (Nb(NO3)5·5H2O) and 8.42 g zirconium nitrate (ZrO(NO3)2·5H2O) were added to 25 mL of deionized water and mixed evenly to obtain solution B.

[0083] (3) Add 4.31 g of diammonium hydrogen phosphate ((NH4)2HPO4) to 25 mL of deionized water to form a homogeneous solution, and obtain solution C.

[0084] (4) Mix the above three solutions A, B and C and evaporate them in a vacuum oven at 125°C for 12 h to form a dry gel.

[0085] (5) After ball milling the dry gel once, it was transferred to a muffle furnace and pre-fired at 300°C for 8 hours to obtain the pre-fired block.

[0086] (6) The pre-burned block obtained in step (5) is subjected to secondary ball milling to obtain secondary powder.

[0087] (7) Sinter the secondary powder obtained in step (6) at 1300℃ for 8 h.

[0088] (8) After the reaction is complete, the mixture is allowed to cool naturally to room temperature to obtain a product with the composition Li. 2.8 Zr 1.8 Nb 0.2 Si2PO 12Niobium ion-doped modified lithium zirconium silicon phosphorus oxide solid electrolyte (LZNSP) material. To obtain nano-LZNSP, the obtained powder is milled using high-energy ball milling and then sintered at 1200℃ for 6 h.

[0089] Example 3

[0090] (1) According to the general formula: Li 2.6 Zr 1.6 Nb 0.4 Si2PO 12 Weigh 20 g of tetraethyl orthosilicate (Si(C2H5O)4) and add it to 100 mL of an aqueous ethanol solution, wherein the volume ratio of ethanol to water is 1:1. Then add 20 g of an aqueous citric acid solution and adjust the pH of the solution to 1.4 with 67% nitric acid to obtain solution A.

[0091] (2) 3.65 g lithium nitrate (LiNO3), 1.12 g niobium nitrate (Nb(NO3)5·5H2O) and 8.42 g zirconium nitrate (ZrO(NO3)2·5H2O) were added to 25 mL of deionized water and mixed evenly to obtain solution B.

[0092] (3) Add 4.31 g of diammonium hydrogen phosphate ((NH4)2HPO4) to 25 mL of deionized water to form a homogeneous solution, and obtain solution C.

[0093] (4) Mix the above three solutions A, B and C and evaporate them in a vacuum oven at 125°C for 12 h to form a dry gel.

[0094] (5) After ball milling the dry gel once, it was transferred to a muffle furnace and pre-fired at 400°C for 8 hours to obtain the pre-fired block.

[0095] (6) The pre-burned block obtained in step (5) is subjected to secondary ball milling to obtain secondary powder.

[0096] (7) Sinter the secondary powder obtained in step (6) at 1300℃ for 8 h.

[0097] (8) After the reaction is complete, the mixture is allowed to cool naturally to room temperature to obtain a product with the composition Li. 2.6 Zr 1.6 Nb 0.4 Si2PO 12 Niobium ion-doped modified lithium zirconium silicon phosphorus oxide solid electrolyte (LZNSP) material. To obtain nano-LZNSP, the obtained powder is milled using high-energy ball milling and then sintered at 1100℃ for 6 h.

[0098] Example 4

[0099] (1) According to the general formula: Li2.4 Zr 1.4 Nb 0.6 Si2PO 12 Weigh 20 g of tetraethyl orthosilicate (Si(C2H5O)4) and add it to 100 mL of an aqueous ethanol solution, wherein the volume ratio of ethanol to water is 1:1. Then add 20 g of an aqueous citric acid solution and adjust the pH of the solution to 1 with 67% nitric acid to obtain solution A.

[0100] (2) 3.27 g lithium nitrate (LiNO3), 1.68 g niobium nitrate (Nb(NO3)5·5H2O) and 8.42 g zirconium nitrate (ZrO(NO3)2·5H2O) were added to 25 mL of deionized water and mixed evenly to obtain solution B.

[0101] (3) Add 4.31 g of diammonium hydrogen phosphate ((NH4)2HPO4) to 25 mL of deionized water to form a homogeneous solution, and obtain solution C.

[0102] (4) Mix the above three solutions A, B and C and evaporate them in a vacuum oven at 125°C for 12 h to form a dry gel.

[0103] (5) After ball milling the dry gel once, it was transferred to a muffle furnace and pre-fired at 350°C for 8 hours to obtain the pre-fired block.

[0104] (6) The pre-burned block obtained in step (5) is subjected to secondary ball milling to obtain secondary powder.

[0105] (7) Sinter the secondary powder obtained in step (6) at 1200℃ for 8 h.

[0106] (8) After the reaction is complete, the mixture is allowed to cool naturally to room temperature to obtain a product with the composition Li. 2.4 Zr 1.4 Nb 0.6 Si2PO 12 Niobium ion-doped modified lithium zirconium silicon phosphorus oxide solid electrolyte (LZNSP) material. To obtain nano-LZNSP, the obtained powder is milled with high-energy balls and then sintered at 1300℃ for 6 h.

[0107] Example 5

[0108] (1) According to the general formula: Li 2.4 ZrNbSi2PO 12 Weigh 20 g of tetraethyl orthosilicate (Si(C2H5O)4) and add it to 100 mL of an aqueous ethanol solution, wherein the volume ratio of ethanol to water is 1:1. Then add 20 g of an aqueous citric acid solution and adjust the pH of the solution to 1 with 67% nitric acid to obtain solution A.

[0109] (2) 2.84 g lithium nitrate (LiNO3), 2.34 g niobium nitrate (Nb(NO3)5·5H2O) and 8.42 g zirconium nitrate (ZrO(NO3)2·5H2O) were added to 25 mL of deionized water and mixed evenly to obtain solution B.

[0110] (3) Add 4.31 g of diammonium hydrogen phosphate ((NH4)2HPO4) to 25 mL of deionized water to form a homogeneous solution, and obtain solution C.

[0111] (4) Mix the above three solutions A, B and C and evaporate them in a vacuum oven at 125°C for 12 h to form a dry gel.

[0112] (5) After ball milling the dry gel once, it was transferred to a muffle furnace and pre-fired at 350°C for 8 hours to obtain the pre-fired block.

[0113] (6) The pre-burned block obtained in step (5) is subjected to secondary ball milling to obtain secondary powder.

[0114] (7) Sinter the secondary powder obtained in step (6) at 1200℃ for 8 h.

[0115] (8) After the reaction is complete, the mixture is allowed to cool naturally to room temperature to obtain a product with the composition Li. 2.4 ZrNbSi2PO 12 Niobium ion-doped modified lithium zirconium silicon phosphorus oxide solid electrolyte (LZNSP) material. To obtain nano-LZNSP, the obtained powder is milled using high-energy ball milling and then sintered at 1200℃ for 6 h.

[0116] Example 6

[0117] (1) According to the general formula: Li 2.7 Zr 1.6 Nb 0.4 Si 1.9 Ga 0.1 PO 12 Weigh 20 g of tetraethyl orthosilicate (Si(C2H5O)4) and 0.31 g of gallium acetate (C6H9GaO6), add 100 mL of an aqueous ethanol solution with a volume ratio of 1:1 to water. Then add 20 g of an aqueous citric acid solution and adjust the pH of the solution to 1 with 67% nitric acid to obtain solution A.

[0118] (2) 3.65 g lithium nitrate (LiNO3), 1.12 g niobium nitrate (Nb(NO3)5·5H2O) and 8.42 g zirconium nitrate (ZrO(NO3)2·5H2O) were added to 25 mL of deionized water and mixed evenly to obtain solution B.

[0119] (3) Add 4.31 g of diammonium hydrogen phosphate ((NH4)2HPO4) to 25 mL of deionized water to form a homogeneous solution, and obtain solution C.

[0120] (4) Mix the above three solutions A, B and C and evaporate them in a vacuum oven at 125°C for 12 h to form a dry gel.

[0121] (5) After ball milling the dry gel once, it was transferred to a muffle furnace and pre-fired at 400°C for 8 hours to obtain the pre-fired block.

[0122] (6) The pre-burned block obtained in step (5) is subjected to secondary ball milling to obtain secondary powder.

[0123] (7) Sinter the secondary powder obtained in step (6) at 1200℃ for 8 h.

[0124] (8) After the reaction is complete, the mixture is allowed to cool naturally to room temperature to obtain a product with the composition Li. 2.7 Zr 1.6 Nb 0.4 Si 1.9 Ga 0.1 PO 12 The niobium-gallium co-doped lithium zirconium silicon phosphorus oxide solid electrolyte (LZNSGP) material is obtained. To obtain nano-LZNSGP, the powder is milled using high-energy ball milling and then sintered at 1200℃ for 6 h.

[0125] Example 7

[0126] (1) According to the general formula: Li 2.8 Zr 1.6 Nb 0.4 Si 1.8 Ga 0.2 PO 12 Weigh 20 g of tetraethyl orthosilicate (Si(C2H5O)4) and 0.63 g of gallium acetate (C6H9GaO6), add 100 mL of an aqueous ethanol solution with a volume ratio of 1:1 to water. Then add 20 g of an aqueous citric acid solution and adjust the pH of the solution to 1 with 67% nitric acid to obtain solution A.

[0127] (2) 3.65 g lithium nitrate (LiNO3), 1.12 g niobium nitrate (Nb(NO3)5·5H2O) and 8.42 g zirconium nitrate (ZrO(NO3)2·5H2O) were added to 25 mL of deionized water and mixed evenly to obtain solution B.

[0128] (3) Add 4.31 g of diammonium hydrogen phosphate ((NH4)2HPO4) to 25 mL of deionized water to form a homogeneous solution, and obtain solution C.

[0129] (4) Mix the above three solutions A, B and C and evaporate them in a vacuum oven at 125°C for 12 h to form a dry gel.

[0130] (5) After the dry gel is ball-milled once, it is transferred to a muffle furnace and pre-fired at 350°C for 8 hours to obtain the pre-fired block.

[0131] (6) The pre-burned block obtained in step (5) is subjected to secondary ball milling to obtain secondary powder.

[0132] (7) Sinter the secondary powder obtained in step (6) at 1200℃ for 8 h.

[0133] (8) After the reaction is complete, the mixture is allowed to cool naturally to room temperature to obtain a product with the composition Li. 2.8 Zr 1.6 Nb 0.4 Si 1.8 Ga 0.2 PO 12 The niobium-gallium co-doped lithium zirconium silicon phosphorus oxide solid electrolyte (LZNSGP) material is obtained. To obtain nano-LZNSGP, the powder is milled using high-energy ball milling and then sintered at 1200℃ for 6 h.

[0134] Example 8

[0135] (1) According to the general formula: Li 2.9 Zr 1.6 Nb 0.4 Si 1.7 Ga 0.3 PO 12 Weigh 20 g of tetraethyl orthosilicate (Si(C2H5O)4) and 0.94 g of gallium acetate (C6H9GaO6), add 100 mL of an aqueous ethanol solution with a volume ratio of 1:1 to water. Then add 20 g of an aqueous ammonium citrate solution and adjust the pH of the solution to 1.2 with 67% nitric acid to obtain solution A.

[0136] (2) 3.65 g lithium nitrate (LiNO3), 1.12 g niobium nitrate (Nb(NO3)5·5H2O) and 8.42 g zirconium nitrate (ZrO(NO3)2·5H2O) were added to 25 mL of deionized water and mixed evenly to obtain solution B.

[0137] (3) Add 4.31 g of diammonium hydrogen phosphate ((NH4)2HPO4) to 25 mL of deionized water to form a homogeneous solution, and obtain solution C.

[0138] (4) Mix the above three solutions A, B and C and evaporate them in a vacuum oven at 125°C for 12 h to form a dry gel.

[0139] (5) After the dry gel is ball-milled once, it is transferred to a muffle furnace and pre-fired at 350°C for 8 hours to obtain the pre-fired block.

[0140] (6) The pre-burned block obtained in step (5) is subjected to secondary ball milling to obtain secondary powder.

[0141] (7) Sinter the secondary powder obtained in step (6) at 1200℃ for 8 h.

[0142] (8) After the reaction is complete, the mixture is allowed to cool naturally to room temperature to obtain a product with the composition Li. 2.8 Zr 1.6 Nb 0.4 Si 1.8 Ga 0.2 PO 12 The niobium-gallium co-doped lithium zirconium silicon phosphorus oxide solid electrolyte (LZNSGP) material is obtained. To obtain nano-LZNSGP, the powder is milled using high-energy ball milling and then sintered at 1200℃ for 6 h.

[0143] Example 9

[0144] (1) According to the general formula: Li3Zr 1.6 Nb 0.4 Si 1.6 Ga 0.4 PO 12 Weigh 20 g of tetraethyl orthosilicate (Si(C2H5O)4) and 1.24 g of gallium acetate (C6H9GaO6), add 100 mL of an aqueous ethanol solution with a volume ratio of ethanol to water of 1:1. Then add 20 g of an aqueous ethylenediaminetetraacetic acid solution and adjust the pH of the solution to 1.5 with 67% nitric acid to obtain solution A.

[0145] (2) 3.65 g lithium nitrate (LiNO3), 1.12 g niobium nitrate (Nb(NO3)5·5H2O) and 8.42 g zirconium nitrate (ZrO(NO3)2·5H2O) were added to 25 mL of deionized water and mixed evenly to obtain solution B.

[0146] (3) Add 4.31 g of diammonium hydrogen phosphate ((NH4)2HPO4) to 25 mL of deionized water to form a homogeneous solution, and obtain solution C.

[0147] (4) Mix the above three solutions A, B and C and evaporate them in a vacuum oven at 125°C for 12 h to form a dry gel.

[0148] (5) After the dry gel is ball-milled once, it is transferred to a muffle furnace and pre-fired at 350°C for 8 hours to obtain the pre-fired block.

[0149] (6) The pre-burned block obtained in step (5) is subjected to secondary ball milling to obtain secondary powder.

[0150] (7) Sinter the secondary powder obtained in step (6) at 1200℃ for 8 h.

[0151] (8) After the reaction was completed, the mixture was allowed to cool naturally to room temperature to obtain Li3Zr. 1.6 Nb 0.4 Si 1.6 Ga 0.4 PO 12 The niobium-gallium co-doped lithium zirconium silicon phosphorus oxide solid electrolyte (LZNSGP) material is obtained. To obtain nano-LZNSGP, the powder is milled using high-energy ball milling and then sintered at 1200℃ for 6 h.

[0152] In addition, solid electrolytes with similar performance can be synthesized by using different lithium sources (lithium nitrate, lithium sulfate, lithium carbonate, lithium acetate, lithium chloride), zirconium sources (zirconium nitrate, zirconium sulfate, zirconium carbonate, zirconium acetate, zirconium chloride), silicon sources (tetraethyl orthosilicate, tetraethyl orthosilicate), oxygen sources, and phosphorus sources (ammonium dihydrogen phosphate, diammonium hydrogen phosphate). These will not be elaborated on here.

[0153] Comparative Example 1

[0154] (1) According to the general formula: Li3Zr 1.6 Nb 0.4 Si 1.6 Ga 0.4 PO 12 Weigh 20 g of tetraethyl orthosilicate (Si(C2H5O)4) and 1.24 g of gallium acetate (C6H9GaO6), add 100 mL of an aqueous ethanol solution with a volume ratio of 1:1 to water. Then add 20 g of an aqueous citric acid solution and adjust the pH of the solution to 1 with 67% nitric acid to obtain solution A.

[0155] (2) 3.65 g lithium nitrate (LiNO3), 1.12 g niobium nitrate (Nb(NO3)5·5H2O) and 8.42 g zirconium nitrate (ZrO(NO3)2·5H2O) were added to 25 mL of deionized water and mixed evenly to obtain solution B.

[0156] (3) Add 4.31 g of diammonium hydrogen phosphate ((NH4)2HPO4) to 25 mL of deionized water to form a homogeneous solution, and obtain solution C.

[0157] (4) Mix the above three solutions A, B and C and evaporate them in a vacuum oven at 125°C for 12 h to form a dry gel.

[0158] (5) After the dry gel is ball-milled once, it is transferred to a muffle furnace and pre-fired at 350°C for 8 hours to obtain the pre-fired block.

[0159] (6) The pre-burned block obtained in step (5) is subjected to secondary ball milling to obtain secondary powder.

[0160] (7) Sinter the secondary powder obtained in step (6) at 1200℃ for 8 h.

[0161] (8) After the reaction was completed, the mixture was naturally cooled to room temperature to obtain the product with the composition Li3Zr2Si2PO4. 12 The lithium zirconium silicon phosphorus oxide type solid electrolyte material is obtained. To obtain nano-LZSP, the powder is ground with high-energy balls and then sintered at 1200℃ for 6 h.

[0162] [Performance Testing]

[0163] 1. XRD Testing

[0164] X-ray diffraction analysis was performed on the ion-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte materials prepared in Examples 1-9 and Comparative Example 1. Figure 1 It can be seen that the products prepared in Examples 1-9 and Comparative Example 1... x =0.1, y =0, x =0.2, y =0, x =0.4 y =0, x =0.6 y =0, x =1、 y =0, x =0.4 y =0.1, x =0.4 y =0.2, x =0.4 y =0.3, x =0.4 y =0.4 and x =0、 y The XRD patterns of lithium zirconium silicon phosphorus oxygen solid electrolyte modified with ion=0 all match the diffraction peaks of the standard card, and no impurity phases are generated.

[0165] 2. Electrochemical performance testing

[0166] To evaluate the practicality of LZNSP and LZNSGP in all-solid-state batteries, an all-solid-state battery was assembled using a metallic Li sheet as the negative electrode and LiFePO4 as the positive electrode.

[0167] All-solid-state battery assembly: The metal Li sheet, the LZNSP prepared in Examples 1-4 (or the LZNSGP prepared in Examples 5-8 or the LZSP prepared in Comparative Example 1), and the LiFePO4 positive electrode sheet are directly assembled into a 2016 type button cell according to the conventional battery assembly sequence.

[0168] The ionic conductivity of the different all-solid-state batteries prepared in Examples 1 to 9 and Comparative Example 1 was tested. The method included: the ionic conductivity σ of the electrolyte film could be calculated by formula (1) from the bulk resistance R in the electrolyte AC impedance spectrum, the area A of the electrolyte film facing the contact electrode, and the thickness d of the electrolyte film.

[0169] Equation (1)

[0170] In addition, the cycle capacity of Examples 1-5 and Comparative Example 1 of this invention was tested after 100 cycles at 0.1C. The cycle capacity test results are shown in Table 1. Observing the data in the table, it can be seen that the solid electrolyte Li3Zr2Si2PO4... 12 Ion doping modification can significantly improve the electrochemical performance and increase the ionic conductivity of solid electrolyte materials. Examples 1-5 compared different niobium doping concentrations, showing that as the Nb doping concentration increases, the ionic conductivity first increases and then decreases. When the Nb doping concentration is x=0.4, the obtained Li... 2.6 Zr 1.6 Nb 0.4 Si2PO 12 It exhibits the best ionic conductivity. Compared to LZSP without niobium in Comparative Example 1, the ionic conductivity is significantly improved. This is because the introduction of niobium ions creates Li vacancies in the solid electrolyte, significantly altering the Li content. + The distribution of Li increases + The jump rate increases the ionic conductivity.

[0171] Based on the above, performance experiments on Nb-Ga co-doped modified LZSP were continued with an Nb doping amount x=0.4. Observing the data from Examples 6-9 in Table 1, it can be seen that when the Ga amount is increased to y=0.3, the ionic conductivity can reach 6.2*10⁻⁶. -3 The discharge capacity at 0.1C for 100 cycles is 648.7 mAh / g (S / cm). Notably, Nb-Ga co-doped LZSP exhibits superior performance compared to single Nb ion doping, with significantly improved ionic conductivity and discharge capacity. This is due to the Nb... 5+ Replace Zr in LZSP 4+ This introduces numerous Li vacancies, increasing the ionic conductivity of LZSP. However, excessive Li vacancies will lead to the formation of mobile Li...+ The concentration is reduced, thus suppressing the increase in ionic conductivity. The introduction of Ga can achieve Ga... 3+ Si replacing LZSP 4+ The concentration of Li vacancies is adjusted by the site, so that LZSP is maintained in a better state. This makes Nb-Ga co-doping more effective than Nb monodoping. After Nb-Ga co-doping modification, LZSP exhibits higher ionic conductivity and greater discharge capacity.

[0172] Table 1 Li 3-x+y Zr 2-x Nb x Si 2-y Ga y PO 12 Comparison of room temperature ionic conductivity of solid electrolyte powders

[0173]

Claims

1. An ion-doped modified lithium-zirconium-silicon-phosphorus-oxygen solid electrolyte, characterized in that, The ion-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte is prepared by adding a niobium gallium source to a mixed solution for preparing the lithium zirconium silicon phosphorus oxygen solid electrolyte via a one-step sol-gel method, and its general formula is Li. 3-x+y Zr 2-x Nb x Si 2-y Ga y PO 12 (0<y≤x≤1 and x≠0).

2. A method for preparing an ion-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte, characterized in that, Includes the following steps: S1. Add the silicon source and the first doped metal source to an ethanol-water solution and mix. Add a complexing agent and adjust the pH of the solution to 1-3 with an inorganic acid to obtain solution A. S2. Add the lithium source, the second doped metal source, and the zirconium source to water and mix to obtain solution B; S3. Add the oxygen source and phosphorus source to water and mix to obtain solution C; S4. Mix solutions A, B, and C and dry them in an oven until a dry gel is formed; S5. After repeating the pulverization and calcination steps of the dry gel at least twice, the general formula Li is obtained. 3-x+y Zr 2-x Nb x Si 2-y Ga y PO 12 (0<y≤x≤1 and x≠0) Ion-doped modified lithium zirconium silicon phosphorus oxygen type solid electrolyte material; wherein, the first doping metal source is selected from one of niobium source and gallium source, and the second doping metal source is selected from one of gallium source and niobium source.

3. The method for preparing an ion-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte according to claim 2, characterized in that, The gallium source is selected from gallium acetate, gallium nitrate, gallium sulfate, gallium citrate, and gallium carbonate, and the niobium source is selected from niobium nitrate, niobium sulfate, niobium carbonate, niobium acetate, and niobium chloride.

4. The method for preparing an ion-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte according to claim 2, characterized in that, In step S1, the silicon source is selected from one of tetraethyl orthosilicate and tetraethyl orthosilicate, the complexing agent is selected from one or more of citric acid, ammonium citrate, maleic acid, oxalic acid, ammonium oxalate, ascorbic acid, and sodium ethylenediaminetetraacetate, and the inorganic acid is selected from one or more of nitric acid, hydrochloric acid, and sulfuric acid.

5. The method for preparing an ion-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte according to claim 2 or 4, characterized in that, In step S1, after adjustment with inorganic acid, the pH of the solution is 1~1.

5.

6. The method for preparing an ion-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte according to claim 2, characterized in that, In step S2, the lithium source is selected from one of lithium nitrate, lithium sulfate, lithium carbonate, lithium acetate, and lithium chloride, and the zirconium source is selected from one of zirconium nitrate, zirconium sulfate, zirconium carbonate, zirconium acetate, and zirconium chloride.

7. The method for preparing an ion-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte according to claim 2 or 6, characterized in that, In step S2, the lithium source needs to be in excess by 5-10 wt%.

8. The method for preparing an ion-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte according to claim 2, characterized in that, In step S3, both the oxygen source and the phosphorus source are derived from ammonium dihydrogen phosphate or diammonium hydrogen phosphate.

9. The method for preparing an ion-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte according to claim 2, characterized in that, In step S5, the calcination temperature after the first pulverization is 300-400℃, and the calcination temperature after the second and subsequent pulverizations is 1100-1300℃; the heating rate during calcination is 1-3℃ / min.

10. The application of the ion-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte as described in claim 1 or the ion-doped modified lithium zirconium silicon phosphorus oxygen solid electrolyte prepared by the methods described in claims 2 to 9 in all-solid-state lithium secondary batteries.

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