Tri (4-methoxyphenyl) phosphate as well as preparation method and application thereof

Abstract

The invention discloses tri (4-methoxyphenyl) phosphate as well as a preparation method and application thereof, the tri (4-methoxyphenyl) phosphate contains three 4-methoxyphenyl groups, and each 4-methoxyphenyl group is respectively bonded to a phosphorus atom of the phosphate through an oxygen atom. According to the invention, the tri (4-methoxyphenyl) phosphate is subjected to a symmetrical tri-substituted configuration (three 4-methoxyphenyl groups are bonded on phosphorus atoms), so that high stability and function controllability of a molecular level are realized. The symmetrical structure ensures that molecules have a directional activation function (such as polymerization or flame retardance) under high pressure or high temperature, and performance fluctuation caused by random decomposition is avoided.

Description

Technical Field

[0001] The present invention relates to the field of lithium batteries, and in particular to tris(4-methoxyphenyl)phosphate, a preparation method and application thereof. Background Art

[0002] As the energy density of lithium-ion batteries continues to increase, the cell capacity and electrolyte usage have increased significantly. However, under extreme conditions such as overcharging and thermal runaway, the cell reacts violently, and the rate of heat and gas generation from electrolyte decomposition increases exponentially, causing a sudden increase in pressure inside the cell and even causing the shell to rupture or explode. This deterioration in safety performance due to increased energy density has become a core bottleneck restricting the commercial application of high-capacity batteries.

[0003] At present, traditional electrolyte systems generally use flammable solvents such as ethylene carbonate (EC) as the main component. Although such solvents have excellent ionic conductivity, their high volatility and low flash point will rapidly intensify the combustion reaction during thermal runaway. For example, when the battery cell temperature exceeds 120°C, the EC solvent will vaporize in large quantities and undergo a chain oxidation reaction with oxygen, releasing a large amount of flammable gases (such as CO, CH 4 ), further triggering heat spread and explosion risk. Summary of the invention

[0004] In order to overcome the defects in the prior art, the first object of the present invention is to provide a tri(4-methoxyphenyl)phosphate, the second object of the present invention is to provide a method for preparing the above-mentioned tri(4-methoxyphenyl)phosphate, the third object of the present invention is to provide an electrolyte comprising the above-mentioned tri(4-methoxyphenyl)phosphate, the fourth object of the present invention is to provide a lithium battery comprising the above-mentioned electrolyte, and the fifth object of the present invention is to provide an electrical device comprising the above-mentioned lithium battery.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] In the first aspect, a tris(4-methoxyphenyl)phosphate ester is provided, wherein the tris(4-methoxyphenyl)phosphate ester contains three 4-methoxyphenyl groups, each of which is bonded to a phosphorus atom of the phosphate ester via an oxygen atom. The structural formula is as follows:

[0007]

[0008] The molecular structure of tri(4-methoxyphenyl)phosphate in the present invention is based on phosphorus atom as the core, three 4-methoxyphenyl (-OC 6 H 4 -OCH 3) form a trigonal pyramidal spatial configuration through symmetrical bonding of oxygen atoms. The benzene ring provides electron delocalization as a rigid skeleton, while the para-methoxy group (4-position) stabilizes the phosphorus atom through an electron-donating effect, reducing its electronegativity to inhibit the reaction with lithium salts (such as LiPF 6 The symmetrically distributed benzene rings form an "umbrella-shaped" steric hindrance, effectively shielding the phosphorus atoms from the electrolyte components (such as Li + PF 6 -), while the electronic regulation of the methoxy group further blocks the phosphorus atom from participating in the competitive coordination reaction, thereby achieving a precise balance between chemical inertness and functional activity at the molecular level.

[0009] The electron delocalization effect refers to an effect in which the electron cloud in a molecule is no longer confined to the localized orbit between two atoms, but extends to a system composed of multiple atoms, thereby reducing the energy of the molecule and increasing its stability.

[0010] In a second aspect, a method for preparing the above-mentioned tris(4-methoxyphenyl)phosphate comprises the following steps:

[0011] The substituted phenol compound and phosphorus oxychloride are mixed in an inert solvent, and an alkaline reagent is added to carry out an etherification reaction to obtain a reaction solution;

[0012] The reaction solution is filtered to remove salt byproducts, washed with a washing solvent and dried to obtain an intermediate product;

[0013] The intermediate product is washed with acid, washed with alkali and dried to obtain tris(4-methoxyphenyl)phosphate.

[0014] Preferably, the substituted phenolic compound is selected from 4-methoxyphenol or butylated hydroxytoluene. 4-methoxyphenol or butylated hydroxytoluene is selected as a raw material, and the high reactivity of the phenolic hydroxyl group (-OH) is used to react with phosphorus oxychloride (POCl 3 ) undergoes a nucleophilic substitution reaction, in which the methoxy group (-OCH 3 ) stabilizes the phosphorus intermediate through the electron donation effect, reduces the activation energy of the substitution reaction, and at the same time, the steric hindrance of the methoxyl group at the para position of the benzene ring is small, so that the three substituents can be symmetrically bonded to the phosphorus atom, accurately constructing the triangular pyramidal structure of the target product; and when butylated hydroxytoluene (BHT) is used as a raw material, although its tert-butyl group increases the steric hindrance, the phenolic hydroxyl group can still participate in the reaction, and tri-substitution can be achieved by adjusting the reaction conditions (such as extending the reaction time). 4-Methoxyphenol is the preferred choice for the reaction raw material, which can ensure the symmetry of the substituents and the reaction efficiency and avoid interference from by-products.

[0015] Preferably, the inert solvent is selected from one of dehydrated tetrahydrofuran, 2-methyltetrahydrofuran, diethoxymethane, and methyl isobutyl copper. Dehydrated tetrahydrofuran (THF) is selected as the inert solvent mainly based on its compatibility with the reaction system and process adaptability. Dehydration treatment effectively blocks phosphorus oxychloride (POCl 3 ) to avoid the hydrolysis side reaction, thus avoiding the generation of acidic impurities; its solubility ensures the phenolic compounds and POCl 3 Full contact promotes efficient nucleophilic substitution reactions; the solvent maintains a liquid homogeneous state at 20-30°C, matching low-temperature reaction conditions to prevent isomerization of substituents; at the same time, the volatility of THF is compatible with subsequent purification steps and can be recycled through distillation recovery, taking into account both process economy and environmental protection, and is conducive to the precise synthesis of the symmetrical configuration of tri(4-methoxyphenyl) phosphate.

[0016] Preferably, the alkaline agent is triethylamine or diisopropylethylamine. Triethylamine or diisopropylethylamine is selected as the alkaline agent to neutralize the HCl generated by the etherification reaction, promote the reaction forward and inhibit the reverse reaction. Both can form soluble ammonium salts to facilitate subsequent filtration and removal, ensure the symmetrical configuration integrity and high purity of the final product tris(4-methoxyphenyl)phosphate, and avoid residual alkaline substances causing hydrolysis or oxidation side reactions during storage.

[0017] Preferably, the molar ratio of the substituted phenol compound, the alkaline agent and phosphorus oxychloride is (3-4): (3.6-4): 1. Further preferably, the molar ratio of the substituted phenol compound, the alkaline agent and phosphorus oxychloride is 3:3.6:1.

[0018] The molar ratio of the substituted phenolic compound to phosphorus oxychloride is (3-4):1, so that the substituted phenolic compound is in excess, providing enough nucleophilic reagent (4-methoxyphenol) to promote phosphorus oxychloride (POCl 3 ) are completely replaced. If the phenols are insufficient, mono- / di-substituted by-products (such as phosphates containing 1-2 phenyl groups) are generated, destroying the symmetry.

[0019] Alkaline reagents are used to neutralize the HCl generated by the reaction. At least 3 mol of base is required for 3 mol of HCl. By setting an excess of at least 20% of the alkaline reagent, complete absorption of HCL is ensured. If the alkaline reagent is insufficient, the unneutralized HCl will trigger a reverse reaction (desubstitution), resulting in partial shedding of the substituent, resulting in an asymmetric configuration of the target product.

[0020] If the substituted phenol compound or alkaline reagent is excessive, the conversion rate can be improved, but the excess reagent will increase the residual mono / disubstituted impurities (such as phenol self-condensation) or alkaline by-products (such as quaternary ammonium salts) to interfere with subsequent purification, resulting in uneven configuration of the final product, thereby weakening its overcharge polymerization ability and flame retardant properties.

[0021] Preferably, the volume of the inert solvent accounts for 30-50% of the volume of the reaction container. The inert solvent is set within this range to ensure that 4-methoxyphenol and phosphorus oxychloride are fully dissolved to form a homogeneous system, and to avoid excessive local concentrations that cause side reactions (such as phenol self-condensation or POCl 3 hydrolysis), while providing sufficient mass transfer space for intermolecular nucleophilic substitution to optimize the reaction rate. Secondly, the inert solvent acts as a thermal buffer medium to absorb the reaction heat (the substitution reaction is an exothermic process), preventing the system from overheating and causing isomerization of the substituent (such as the generation of ortho-position byproducts) or hydrolysis of the phosphorus atom, thereby ensuring the symmetry of the tri-substituted configuration. In addition, 30-50% of the solvent volume provides precipitation and escape space for the salt byproducts (such as triethylamine hydrochloride) after the HCl gas generated by the reaction and the neutralization of the alkaline reagent, avoiding the risk of pressure accumulation or liquid overflow. At the same time, the reserved container space facilitates the stirring paddle to efficiently mix the materials and prevent "dry running" or splashing. In the post-processing stage, the moderate solvent volume makes the reaction liquid have suitable fluidity, which is beneficial for the rapid filtration of salt byproducts and avoids excessive solvent from increasing the energy consumption of the washing step.

[0022] If the volume of the inert solvent is less than 30%, the reactant concentration is too high, causing exothermic runaway, the by-product content increases (mono / disubstituted impurities), and the system viscosity increases, resulting in obstructed mass transfer. If it exceeds 50%, the dilution effect significantly reduces the reaction rate, prolongs the reaction time, and increases the energy consumption of solvent recovery. Therefore, the 30-50% inert solvent volume becomes a key parameter to ensure the symmetrical configuration, high purity and process safety of the target product through precise control of dissolution, mass transfer, heat dissipation and process adaptability.

[0023] Preferably, the temperature of the etherification reaction is 20-30° C., and the stirring time is 48-52 hours.

[0024] The etherification reaction temperature is controlled at 20-30°C and the stirring time is set to 48-52 hours. The hydrolysis of phosphorus oxychloride and phenolic side reactions (such as self-condensation or ortho-substitution) are suppressed by low temperature. At the same time, sufficient reaction time ensures that the three methoxyphenyl groups gradually replace the chlorine on the phosphorus atom to form a symmetrical configuration. The solvent properties (low viscosity, moisture resistance) of dehydrated tetrahydrofuran and the neutralization effect of triethylamine work together to promote the reaction in the direction of the target product, while continuous stirring maintains a homogeneous system to avoid incomplete substitution due to local uneven concentration. This temperature-time combination ensures the uniformity of the configuration of the trisubstituted product by balancing the reaction kinetics and thermodynamics. If the temperature is too high or the time is insufficient, the risk of side reactions increases significantly, destroying the symmetry of the product and affecting its functional performance in the electrolyte.

[0025] Preferably, the reaction solution is filtered to remove salt by-products, washed with a washing solvent and dried to obtain an intermediate product, wherein:

[0026] The washing solvent is tetrahydrofuran; the washing times are at least 3 times;

[0027] The drying temperature is 40-60°C and the drying time is 2-4 hours.

[0028] Tetrahydrofuran (THF) was selected as the washing solvent mainly based on its compatibility with the reaction system and solubility characteristics. THF has moderate polarity and can effectively dissolve unreacted 4-methoxyphenol and mono / disubstituted intermediates, and can form a homogeneous solution with salt byproducts (such as triethylamine hydrochloride), which is easy to separate by filtration. At the same time, the low boiling point (66°C) of tetrahydrofuran makes it easy to volatilize and remove in the subsequent drying step, avoiding residual solvents from interfering with the purity of the product.

[0029] Set the number of washes to at least 3 times. Multiple washes can gradually reduce the concentration of impurities. The first wash removes most salts and unreacted products. The second wash further removes residual intermediates. The third wash ensures that trace impurities are completely removed. If the number of washes is insufficient, residual impurities may cause hydrolysis or oxidation side reactions during storage, destroying the symmetrical configuration of the product and causing the flame retardant or overcharge protection function in the electrolyte to fail.

[0030] By drying, the residual solvent and water after washing are removed.

[0031] The core purpose of the drying step is to completely remove the residual solvent and trace moisture after washing, ensuring the chemical stability of the intermediate product and the effectiveness of the subsequent purification steps.

[0032] Preferably, the intermediate product is acid-washed, alkaline-washed and dried to obtain the target product, wherein:

[0033] The acid washing adopts a hydrochloric acid solution with a concentration of 5-7%, and the alkali washing adopts a sodium hydroxide solution with a concentration of 5-7%;

[0034] The drying process uses phosphorus pentoxide as a desiccant and is dried in a vacuum oven for 12-24 hours. The temperature of the vacuum oven is set at 65° C.-86° C.

[0035] By acid washing, hydrochloric acid can neutralize the residual alkaline reagent (such as triethylamine or its hydrochloride) and convert it into water-soluble triethylamine hydrochloride, which is convenient for water washing and separation. By alkali washing, the hydrochloric acid and acidic by-products remaining in the acid washing are neutralized and the system is adjusted to neutral or weak alkalinity.

[0036] Phosphorus pentoxide is used as a desiccant and dried in a vacuum oven for 12-24 hours. The purpose is to completely remove the moisture in the product through the synergistic effect of efficient moisture absorption and mild conditions. Phosphorus pentoxide is a strong desiccant, and its hygroscopicity far exceeds that of silica gel or molecular sieves, effectively blocking the hydrolysis side reaction caused by residual moisture.

[0037] The etherification reaction equation in the present invention is as follows:

[0038]

[0039] The symmetrical bonding of the substituents is strictly controlled during the etherification reaction stage. 4-methoxyphenol and phosphorus oxychloride are accurately fed in a 3:1 molar ratio, and reacted at a low temperature of 20-30°C in a dehydrated tetrahydrofuran solvent. Triethylamine promptly neutralizes the generated HCl to prevent reverse reaction. The dehydrated tetrahydrofuran solvent promotes uniform dispersion of the molecules, ensuring that the three methoxyphenyl groups completely replace the chlorine on the phosphorus atom. Subsequently, the triethylamine hydrochloride byproduct is removed by filtration, and the mono / disubstituted intermediates and unreacted raw materials are removed by three washings with tetrahydrofuran to achieve trisubstituted configuration purification. Further, 5-7% hydrochloric acid is used to neutralize the residual alkali and remove hydrolysis impurities, and sodium hydroxide is used to eliminate acidic byproducts, and the pH is adjusted simultaneously to avoid methoxy demethylation. Finally, the water is removed by vacuum drying with phosphorus pentoxide to block the risk of hydrolysis during storage, and the symmetrical triangular pyramid configuration of tris(4-methoxyphenyl) phosphate is guaranteed from multiple dimensions, including reaction kinetics, byproduct removal, and physicochemical stability.

[0040] In a third aspect, a lithium battery electrolyte having the above tris(4-methoxyphenyl)phosphate comprises:

[0041] Lithium salt, wherein the lithium salt is lithium hexafluorophosphate with a concentration of 1 mol / L;

[0042] A carbonate solvent including dimethyl carbonate and ethylene carbonate in a volume ratio of 7:3;

[0043] Tris(4-methoxyphenyl)phosphate accounts for 1-5wt% of the total mass of the electrolyte.

[0044] Preferably, the tris(4-methoxyphenyl)phosphate accounts for 1-5 wt % of the total mass of the electrolyte.

[0045] In a fourth aspect, a lithium battery comprises the above-mentioned lithium battery electrolyte.

[0046] In a fifth aspect, an electrical device comprises the above-mentioned lithium battery.

[0047] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0048] 1. In the present invention, tri(4-methoxyphenyl) phosphate achieves high stability and functional controllability at the molecular level through a symmetrical trisubstituted configuration (three 4-methoxyphenyl groups bonded to the phosphorus atom). The rigid skeleton of the benzene ring and the electron-donating effect of the methoxy group work synergistically to not only enhance thermal stability. It also shields the side reactions of phosphorus atoms and electrolyte components through "umbrella-shaped" steric hindrance. The symmetrical structure ensures that the molecule activates functions (such as polymerization or flame retardancy) in a directional manner under high pressure or high temperature, avoiding performance fluctuations caused by random decomposition. Compared with traditional mono / disubstituted phosphates, this design enables the electrolyte additive to trigger the protection mechanism only under specific conditions while maintaining inertness, taking into account both normal performance and extreme operating safety.

[0049] 2. Tris(4-methoxyphenyl) phosphate improves battery safety through dual mechanisms. Overcharge protection: At 4.35V (relative to Li / Li + ) Under high temperature, the methoxyl group is oxidized and demethylated to generate free radicals, which trigger intermolecular cross-linking to form a conductive polymer network, bypassing the overcharge current and preventing voltage runaway. Flame retardant performance: At high temperatures, phosphorus atoms release PO·-containing free radicals to quench the H· / HO· active species of the combustion chain reaction. At the same time, the benzene ring is carbonized to form a pyrophosphate barrier to isolate oxygen and heat. This dual mechanism breaks through the limitations of the single function of traditional additives, provides active protection in multiple scenarios such as overcharging and thermal runaway, and the triggering conditions are precisely controllable to avoid performance loss caused by misactivation of the function. While ensuring that the performance of the battery cell remains unchanged, the safety performance of the battery cell is greatly improved.

[0050] 3. This preparation process breaks through the bottlenecks of incomplete substitution and complicated purification in traditional phosphate synthesis and is suitable for large-scale production.

[0051] In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0053] Figure 1 These are the electrochemical performance test results of the lithium batteries prepared using the electrolytes in Example 1 and Comparative Examples 1, 2, and 3 of the present invention. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] Embodiment 1:

[0056] A tris(4-methoxyphenyl) phosphate, wherein the tris(4-methoxyphenyl) phosphate contains three 4-methoxyphenyl groups, each of which is bonded to a phosphorus atom of the phosphate via an oxygen atom. The structural formula is as follows:

[0057]

[0058] This embodiment also discloses a method for preparing the above tris(4-methoxyphenyl)phosphate, comprising the following steps:

[0059] In a 500 ml three-necked flask, 0.3 mol of 4-methoxyphenol and 0.36 mol of triethylamine were placed in 200 ml of dehydrated tetrahydrofuran, and then 0.1 mol of phosphorus oxychloride was added to the three-necked flask for etherification reaction, and the mixed reaction solution was stirred at 20-30°C for 48 hours.

[0060] The triethylamine chloride obtained in the etherification reaction was filtered out through a filter cannula with a tip, and the filtered solid product was washed five times with tetrahydrofuran and then dried to obtain an oily product, p-methoxyphenyl phosphate.

[0061] The p-methoxyphenyl phosphate is washed with a 5% hydrochloric acid solution and a 5% sodium hydroxide solution in sequence, and then dried in a vacuum oven using phosphorus pentoxide as a desiccant.

[0062] This embodiment also discloses a lithium battery electrolyte, comprising:

[0063] Lithium salt, wherein the lithium salt is lithium hexafluorophosphate with a concentration of 1 mol / L;

[0064] A carbonate solvent including dimethyl carbonate and ethylene carbonate in a volume ratio of 7:3;

[0065] Tris(4-methoxyphenyl)phosphate accounts for 3.5 wt% of the total mass of the electrolyte.

[0066] The electrolyte was prepared and stored in a glove box filled with high-purity argon (water and oxygen both <0.01 ppm).

[0067] Comparative Example 1:

[0068] This comparative example discloses a method for preparing a lithium battery electrolyte, comprising the following steps:

[0069] In a 500 ml three-necked flask, 1 mol of 4-methoxyphenol and 0.36 mol of triethylamine were placed in 200 ml of dehydrated tetrahydrofuran, and then 0.1 mol of phosphorus oxychloride was added to the three-necked flask for etherification reaction, and the mixed reaction solution was stirred at 20-30°C for 48 hours.

[0070] The triethylamine chloride obtained in the etherification reaction was filtered out through a filter cannula with a tip, and the filtered solid product was washed five times with tetrahydrofuran and then dried to obtain an oily product, p-methoxyphenyl phosphate.

[0071] The p-methoxyphenyl phosphate is washed with a 5% hydrochloric acid solution and a 5% sodium hydroxide solution in sequence, and then dried in a vacuum oven using phosphorus pentoxide as a desiccant to obtain p-methylphenyl phosphate.

[0072] The p-methylphenyl phosphate is used to prepare a lithium battery electrolyte in the following ratio; the electrolyte comprises:

[0073] Lithium salt, wherein the lithium salt is lithium hexafluorophosphate with a concentration of 1 mol / L;

[0074] A carbonate solvent including dimethyl carbonate and ethylene carbonate in a volume ratio of 7:3;

[0075] p-Toluene phosphate, which accounts for 3.5wt% of the total mass of the electrolyte.

[0076] The electrolyte was prepared and stored in a glove box filled with high-purity argon (water and oxygen both <0.01 ppm).

[0077] Comparative Example 2:

[0078] A lithium battery electrolyte, comprising:

[0079] Lithium salt, wherein the lithium salt is lithium hexafluorophosphate with a concentration of 1 mol / L;

[0080] The carbonate solvent includes dimethyl carbonate and ethylene carbonate in a volume ratio of 7:3.

[0081] The electrolyte was prepared and stored in a glove box filled with high-purity argon (water and oxygen both <0.01 ppm).

[0082] Comparative Example 3:

[0083] A lithium battery electrolyte, comprising:

[0084] Lithium salt, wherein the lithium salt is lithium hexafluorophosphate with a concentration of 1 mol / L;

[0085] A carbonate solvent including dimethyl carbonate and ethylene carbonate in a volume ratio of 7:3;

[0086] Vinyl sulfate, which accounts for 3.5wt% of the total mass of the electrolyte.

[0087] The electrolyte was prepared and stored in a glove box filled with high-purity argon (water and oxygen both <0.01 ppm).

[0088] Lithium batteries were prepared using the electrolytes in Example 1, Comparative Examples 1, 2, and 3 according to conventional lithium battery preparation methods. The lithium battery includes a positive electrode, a negative electrode, an electrolyte, and a separator. The electrolyte is the electrolyte prepared in Example 1, Comparative Examples 1, 2, and 3. The positive electrode material includes lithium iron phosphate, conductive carbon black, and polyvinylidene fluoride, and the weight ratio is 97:1:2. The coating amount on each side of the positive electrode current collector is 16.0 mg / cm 2 The positive electrode current collector is a three-layer composite aluminum foil (total thickness 13+1+1μm). The negative electrode material includes graphite, acrylic acid ester aqueous binder, conductive carbon black, carbon nanotubes and sodium carboxymethyl cellulose, with a weight ratio of 96:2.3:0.9:0.4:0.4, and the coating amount on each side of the negative electrode current collector is 10.1mg / cm 2 The negative electrode current collector is copper foil (thickness 6.0μm). The separator is a ceramic-coated polyethylene film. The negative electrode capacity / positive electrode capacity ≈ 1.13.

[0089] The prepared lithium battery was tested as follows:

[0090] 1. The electrochemical behavior of (tri(4-methoxyphenyl)phosphate was detected by cyclic voltammetry (CV). The working electrode was a platinum microdisk electrode with a diameter of 0.1 mm. The recording was performed in a two-electrode cell, and a larger lithium sheet was used as both the counter electrode and the reference electrode. Data acquisition and analysis were completed by a CHI 660A electrochemical workstation.

[0091] Figure 1 The electrochemical performance test results are shown in the figure. As shown in the figure, Example 1 has a high + Significant polymerization reaction occurs, while no polymerization can be achieved in Comparative Examples 1, 2 and 3 without the addition of tris(4-methoxyphenyl)phosphate. The electropolymer can protect the battery from voltage runaway during overcharging by bypassing the overcharge current inside the battery.

[0092] 2. Take 1g of solute from each of the above Example 1 and Comparative Examples 1, 2 and 3, and observe the combustion time and the presence or absence of combustion.

[0093] 3. Battery cycle performance test of LFP positive electrode material, the battery charge and discharge voltage range is set to 2.5-3.65V (relative to lithium metal / lithium ion reference electrode).

[0094] The test results are shown below:

[0095] plan Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Burning test <![CDATA[0sOsg -1 ]]> <![CDATA[0s85sg -1 ]]> <![CDATA[0s73sg -1 ]]> <![CDATA[0s72sg -1 ]]> LFP / Gr500 circle 0.96 0.87 0.91 0.95

[0096] The test results show that the solute in the electrolyte in Example 1, Comparative Examples 1, 2, and 3 starts from time 0s, and the time per gram of combustion is 0s, 85s, 73s, and 72s, respectively. From the above results, it can be seen that after adding tris(4-methoxyphenyl)phosphate to the electrolyte, the flame retardant property is higher. In addition, from the test results of the battery cycle performance, it can be seen that after adding tris(4-methoxyphenyl)phosphate to the electrolyte, the performance of the battery cell does not change.

[0097] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A tris(4-methoxyphenyl)phosphate, characterized in that The tris(4-methoxyphenyl)phosphate contains three 4-methoxyphenyl groups, and each 4-methoxyphenyl group is bonded to a phosphorus atom of the phosphate through an oxygen atom.

2. A method for preparing tris(4-methoxyphenyl)phosphate as claimed in claim 1, characterized in that: The following steps are involved: The substituted phenol compound and phosphorus oxychloride are mixed in an inert solvent, and an alkaline reagent is added to carry out an etherification reaction to obtain a reaction solution; The reaction solution is filtered to remove salt byproducts, washed with a washing solvent and dried to obtain an intermediate product; The intermediate product is washed with acid, washed with alkali and dried to obtain tris(4-methoxyphenyl)phosphate.

3. The method according to claim 2, characterized in that: The substituted phenol compound is selected from 4-methoxyphenol or butylated hydroxytoluene; The inert solvent is selected from one of dehydrated tetrahydrofuran, 2-methyltetrahydrofuran, diethoxymethane, and methyl isobutyl copper; The alkaline agent is triethylamine or diisopropylethylamine.

4. The method according to claim 2, characterized in that: The molar ratio of the substituted phenol compound, the alkaline reagent and phosphorus oxychloride is (3-4):(3.6-4):1; the volume of the inert solvent accounts for 30-50% of the capacity of the reaction container; Preferably, the molar ratio of the substituted phenol compound, the alkaline agent and phosphorus oxychloride is 3:3.6:

1.

5. The method according to claim 2, characterized in that: The temperature of the etherification reaction is 20-30° C., and the stirring time is 48-52 hours.

6. The method according to claim 2, characterized in that: The reaction solution is filtered to remove salt byproducts, washed with a washing solvent and dried to obtain an intermediate product, wherein: The washing solvent is tetrahydrofuran, and the washing times are at least 3 times; The drying temperature is 40-60°C and the drying time is 2-4 hours.

7. The method according to claim 2, characterized in that: The intermediate product is acid-washed, alkaline-washed and dried to obtain the target product, wherein: The acid washing adopts a hydrochloric acid solution with a concentration of 5-7%, and the alkali washing adopts a sodium hydroxide solution with a concentration of 5-7%; The drying process uses phosphorus pentoxide as a desiccant and is carried out in a vacuum oven for 12-24 hours.

8. A lithium battery electrolyte comprising the tris(4-methoxyphenyl)phosphate of claim 1, characterized in that: include: Lithium salt, wherein the lithium salt is lithium hexafluorophosphate with a concentration of 1 mol / L; A carbonate solvent including dimethyl carbonate and ethylene carbonate in a volume ratio of 7:3; Tris(4-methoxyphenyl)phosphate accounts for 1-5wt% of the total mass of the electrolyte.

9. A lithium battery, characterized in that: Including the lithium battery electrolyte as described in claim 8.

10. An electrical device, characterized in that: Including the lithium battery as described in claim 9.

Images