CN101130583A - Synthesis and Application of Organic Radical Polymer PTMA Cathode Material for Lithium Secondary Batteries - Google Patents

Abstract

Synthesis and application of organic radical polymer PTMA electrode material for lithium secondary battery. Using HTMP and MMA as precursors, MTMP was prepared by an optimized transesterification synthesis method, hydroquinone or metal copper was used as a polymerization inhibitor, metal sodium or magnesium methoxide was used as a catalyst to prepare MTMP; then MTMP was used as a monomer, and AIBN was used as an initiator The polymer PMTMP was prepared by free radical bulk polymerization in toluene solution. PMTMP uses Na ₂ WO ₄ -H ₂ O ₂ -EDTA as an oxidant in methanol solution to obtain PTMA with nitrogen and oxygen stable free radicals in its side chain. The characteristics of PTMA as a new organic polymer cathode material for lithium secondary batteries are: 85.5% of the battery capacity can be fully charged at 10C for 6 minutes, 93.5% of the capacity at 10C discharge at 0.2C discharge, and the discharge voltage is stable (about 3.5V) , the capacity decays slowly. After 300 charge and discharge cycles, the battery discharge capacity only decays by 2.0% relative to the maximum discharge capacity. It does not generate heat during charge and discharge, eliminating potential safety hazards caused by temperature rise. It has good compatibility with the electrolyte. Biodegradable and environmentally friendly.

Description

Synthesis and Application of Organic Radical Polymer PTMA Cathode Material for Lithium Secondary Batteries

technical field

The invention relates to a synthesis process and application of free radical polymer PTMA (poly 4-methacrylic acid-2,2,6,6-tetramethylpiperidine-1-nitroxyl free radical).

Background technique

Since the discovery of nitrogen-oxygen-stabilized free radicals in 1956, the special stability of nitrogen-oxygen-stabilized free genes has enabled them to be widely used in cancer chemistry, radiation chemistry, excited state chemistry, and spin labeling. The study of nitroxide-stabilized free radicals has become a very active field in free radical chemistry and biochemistry and has developed rapidly.

The most studied and most promising among the nitroxide stable radicals is 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl radical (2,2,6,6-tetramethyl-4 -piperidine-1-oxyl, referred to as TEMPO) and its derivatives. The synthesis of its ester derivatives has been reported, and K.Murayama et al. synthesized 4-methacrylic acid-2,2,6,6-tetramethylpiperidinol ester (4-methacryloxy-2,2 , 6,6-tetramethylpiperdine, referred to as MTMP); in 1972, Toshikazu Kurosaki and others also synthesized this compound by a similar method; in 1979, Lu Qihao and others prepared MTMP through transesterification; in 1996, Wang Yukun passed it in a mixed solvent of xylene and benzene MTMP was also prepared by transesterification.

Free radical polymers, as a brand-new cathode material system for lithium secondary batteries, began in 2002 when Nakahara K discovered that free radical polymers can convert electrical energy to chemical energy through redox reactions, that is, the process of gaining and losing electrons. The free radical polymer repeatedly undergoes oxidation-reduction reactions during the charge-discharge cycle, that is, electron transfer reactions occur with the current collector, while its molecular chain structure does not change, and no single anions and cations are generated during the oxidation-reduction process. Free radicals, it is neither like organic sulfides that will break the S-S bond during the charge-discharge cycle and become a small molecular substance that dissolves in the electrolyte or the structure is destroyed, resulting in capacity fading, nor like inorganic layered transition metals Due to the intercalation and intercalation of lithium ions during the charge and discharge of oxides, their structures are unstable, resulting in capacity fading and poor rapid charge and discharge performance during charge and discharge cycles. Therefore, due to its excellent electrochemical cycle stability (see Figure 8), reversibility (see Figure 7) and high-current charge-discharge performance (see Figures 9, 10 and 11), free radical polymers are rich in raw material resources and inexpensive. Inexpensive and non-toxic, good compatibility with electrolyte, biodegradable, easy to improve its physical and chemical properties by changing the composition and structure of organic groups, or copolymerizing or blending with several organic compounds with expected structural characteristics , will become a new type of energy storage material with the most application prospects.

Contents of the invention

The present invention uses 2,2,6,6-tetramethyl-4-hydroxypiperidine (2,2,6,6-tetramethyl-4-piperidine, referred to as HTMP) and methyl methacrylate (methyl methacrylate, referred to as MMA ) is the precursor to synthesize MTMP, and then polymerized and oxidized to become PTMA (poly 4-methacrylic acid-2,2,6,6-tetramethylpiperidine-1-nitroxygen) with stable free radical polymers in the side chain Free radicals, poly(2,2,6,6-tetramethyl-piperidinyloxy methacrylate, referred to as PTMA), by studying the electrochemical properties of PTMA, a nitrogen-oxygen-stabilized free radical polymer, opened up the use of free radical polymers in the energy field and anti-aging materials Applications.

One of the purposes of the present invention is to provide a kind of synthetic technology method that takes HTMP and MMA as precursor, synthesizes the polymer PTMA that side chain has nitroxide stable free radical through esterification, polymerization and oxidation reaction.

The second object of the present invention is to provide a new idea of PTMA as the positive electrode material of lithium secondary battery, break the situation that the inorganic metal oxides of lithium secondary battery positive electrode materials dominate the world, and open up the organic free radical polymer as lithium secondary battery The new field of battery positive electrode materials has a certain positive effect on promoting the development of lithium secondary batteries.

The purpose of the present invention is achieved in the following manner:

The preparation of PTMA material of the present invention comprises the following steps:

(1) Using HTMP and MMA as precursors, using hydroquinone or metal copper as a polymerization inhibitor, magnesium methoxide or metal sodium as a catalyst, and using optimized transesterification synthesis to prepare MTMP;

(2) Purifying the obtained MTMP, using MTMP as a monomer and AIBN as an initiator to prepare polymer PMTMP by free radical bulk polymerization;

(3) The precursor PMTMP, using sodium tungstate-hydrogen peroxide-ethylenediaminetetraacetic acid disodium in methanol solution as an oxidant, oxidizes the polymer PMTMP into a free radical polymer with nitrogen-oxygen stable free radicals in the side chain PTMA.

In the (1) step, add HTMP and excess MMA to the reaction fractionation column, heat to boiling, the temperature at the top of the column gradually rises to 95-105°C, keep at this temperature for another 10-20 minutes, and the reaction is completed ; Remove excess MMA by vacuum distillation, continue vacuum distillation, collect 94 ~ 96 ° C, 0.4 ~ 0.5KPa fraction, which is MTMP.

In the step (1), magnesium methylate is made of magnesium powder and methanol as raw materials, and iodine is used as an initiator. After reacting for 1 to 2 hours, until no hydrogen gas is released, the reaction solution turns into a white paste to obtain magnesium methylate.

In the step (2), add MTMP, initiator AIBN, and solvent toluene into the reaction kettle, degas it in vacuum, fill it with argon, polymerize at a temperature of 55-65°C for 10-14h, and separate the polymer. Vacuum-dried to obtain a white powdery solid, which is poly-2,2,6,6-tetramethylpiperidinol 4-methacrylate (PMTMP).

In the (2) step, the purification of MTMP is to first filter with a sand core funnel; under stirring, the filtrate is dripped into 6-10 times the volume of water, the precipitate is filtered, washed with water, air-dried, and vacuum-dried at room temperature to constant weight. White crystals were obtained.

In the step (3), the oxidation time of the polymer PMTMP is 30 to 40 hours.

The invention applies PTMA to lithium secondary battery as positive electrode material.

The present invention adopts with HTMP and MMA as precursor, by esterification, polymerization and oxidation reaction synthetic side chain has the polymer PTMA of nitroxide stable free radical, (1) the synthetic route of PTMA is as Fig. 1, (2) PTMA is prepared The process principle is shown in Figure 2.

The present invention preferably replaces hydroquinone with metallic copper as a polymerization inhibitor, so that the purification of MTMP is easier, because metallic copper is a solid, after the reaction finishes, it is sufficient to filter and separate metallic copper, and metallic copper does not bring Any by-products that are difficult to separate, so the product MTMP obtained does not contain a polymerization inhibitor, which is conducive to the polymerization of MTMP. The yield of this synthesis method is 92.6%, and it is white needle-like crystal after cooling.

The PTMA synthesized by the present invention has the following characteristics as a brand-new organic polymer positive electrode material for lithium secondary batteries: 85.5% of the battery capacity can be fully charged at a charging rate of 10C in 6 minutes, and the capacity when discharging at 10C is 93.5% when discharging at 0.2C. %, the discharge voltage is stable (about 3.5V), and the capacity decays slowly. After 300 charge-discharge cycles, the discharge capacity of the battery is only attenuated by 2.0% relative to the maximum discharge capacity. There is no heat during the charge-discharge process, and the temperature rise due to temperature rise is eliminated. High safety hazards, good compatibility with electrolyte, biodegradability, and environmental friendliness.

The advantage of synthetic technique of the present invention is:

(1) Using HTMP and MMA as precursors, hydroquinone or metal copper as polymerization inhibitor, magnesium methoxide or metal sodium as catalyst, MTMP was synthesized by optimized transesterification. Optimizing the transesterification method, first-selected metal copper as a polymerization inhibitor and metal sodium as a catalyzer, avoiding the polymerization of methyl methacrylate in the transesterification synthesis reaction process, and reducing the yield (if methyl methacrylate has occurred) polymerization reaction, the yield is very low), and the separation of MTMP will be more difficult. After using metal copper instead of hydroquinone as a polymerization inhibitor, the purification of MTMP is relatively easy, because metal copper is a solid, after the reaction is over, the metal copper can be separated by filtration, and the metal copper does not bring any difficult separation to the reaction product. By-product, so the product MTMP that obtains does not comprise polymerization inhibitor, is conducive to the polymerization reaction of MTMP like this. Therefore, optimizing the transesterification method not only improves the yield of MTMP but also facilitates the purification of MTMP, and is beneficial to the polymerization of MTMP.

(2) MTMP purification, using acetone-water as a mixed solvent, the purification operation of purifying MTMP is simple and convenient, and crystallization is produced from the filtrate and mother liquor, so that almost all of MTMP is precipitated.

(3) With MTMP as a monomer and AIBN as an initiator, the polymer is isolated by free radical polymerization in toluene solvent, and dried in vacuum to obtain a white powdery solid poly-4-methacrylic acid-2,2,6,6-tetra Methyl piperidinol ester (PMTMP). PMTMP uses sodium tungstate-hydrogen peroxide-ethylenediaminetetraacetic acid disodium as an oxidant in a methanol solution to oxidize the polymer PMTMP into a free radical polymer PTMA with nitrogen and oxygen stable free radicals in the side chain, and can obtain high yield The side chain of the rate has PTMA with nitrogen and oxygen stable free radicals.

Description of drawings

Figure 1 is the synthetic route of PTMA.

Figure 2 is the process principle of PTMA preparation.

Fig. 3 prepares the reaction equation of catalyst magnesium methylate.

Fig. 4 Infrared spectra of HTMP, MTMP, PMTMP and PTMA.

Figure 5 UV-Vis spectra of PTMA and PMTMP.

Figure 6 ESR spectrum of PTMA.

Figure 7 The positive electrode reaction of the free radical polymer during charge and discharge.

Figure 8 Cathode reaction of PTMA/lithium secondary battery.

Figure 9 Overall reaction of PTMA/Li secondary battery.

Figure 10Charge and discharge curves of PTMA/Li battery.

Figure 11 Cycle curve of PTMA/Li battery.

Figure 12 Charge and discharge curves of PTMA/Li battery at the same discharge rate under different charge current conditions.

Figure 13 Charge and discharge curves of PTMA/Li battery at the same discharge rate under different charge current conditions.

Figure 14 Charge and discharge curves of PTMA/Li battery at different discharge rates under the same charge current condition.

Figure 15 The charge and discharge curves of the PTMA button cell when metal lithium sheets and carbon are the negative electrodes.

Figure 16 Cycle curve of PTMA button cell when metal lithium sheet and carbon are negative electrodes.

Detailed ways

Example 1

(1) Chemical pretreatment process of raw materials, 2,2,6,6-tetramethyl-4-hydroxypiperidine (abbreviated as HTMP), used by benzene-ethanol recrystallization, mp128～129℃; methyl methacrylate (referred to as MMA), methyl methacrylate is distilled after drying with molecular sieves; metal copper (99.9%); magnesium powder (active magnesium content 99.0%); ; The solvent tetrahydrofuran and ether were dried with CaCl ₂ and evaporated by sodium benzophenone for use.

(2) The preparation process of catalyst magnesium methanolate, adding magnesium powder and methanol in a reactor with a stirrer, and then putting a small amount of iodine as an initiator, after 2 to 3 minutes of normal temperature reaction, the color of iodine fades and begins to emit Hydrogen gas, after 1-2 hours of reaction, no hydrogen gas is released, the reaction solution turns into a white paste, and magnesium methoxide is obtained. The reaction equation is shown in Figure 3:

(3) The MTMP process is prepared by transesterification, adding 1000g of HTMP and 1000g of MMA to the reaction fractionation tower, and then adding 10 to 20g of catalyst (such as: magnesium methylate or sodium metal) and polymerization inhibitor (such as: terephthalate Phenol or metal copper), heated to boiling, and the methanol fraction was fractionated at the top of the column. The temperature at the top of the column was gradually raised to 90-120° C., kept at this temperature for another 15-30 minutes, and the reaction was completed. Then vacuum distillation to remove excess methyl methacrylate, continue vacuum distillation, collect 94 ~ 96 ° C / 0.4 ~ 0.5KPa fraction, which is 4-methacrylic acid-2,2,6,6-tetramethyl Methyl piperidinol (MTMP).

(4) The purification process of MTMP, the crude product of MTMP is dissolved in acetone solution to obtain the acetone solution of MTMP, which is filtered with a sand core funnel. Under stirring, drop the filtrate into about 8 times the volume of water, filter the precipitate, wash with water, air-dry, and vacuum-dry at room temperature to constant weight to obtain white crystal MTMP with a melting point of 58-59°C. Using acetone-water as a mixed solvent, according to the general method, crystallization is produced from the filtrate and mother liquor, so that almost all MTMP is precipitated.

(5) The synthesis process of PMTMP, 1000g monomer (MTMP), 5-20g AIBN and 2000-3000g toluene are added to the reaction kettle, and after a certain period of reaction at a temperature of about 45-60°C, the polymer is separated. Vacuum-dried to constant weight to obtain a white powdery solid, which is poly-2,2,6,6-tetramethylpiperidinol 4-methacrylate (PMTMP). Because the precursor monomer MTMP is insoluble in the solvent, the polymerization is initially in a heterogeneous state, and as the polymerization progresses, the reaction mixture becomes monophasic and viscous. After a certain polymerization time, the solvent was distilled off under reduced pressure, the crude product was recrystallized with methanol and ether, and after vacuum drying, a white powder solid PMTMP was obtained with a yield of 92%.

(6) The synthesis process of PTMA, add water, methanol and 30% hydrogen peroxide, and a small amount of sodium tungstate and disodium ethylenediaminetetraacetic acid (EDTA) in the reaction kettle, stir and dissolve, then add PMTMP, stir reaction, the solution changed from colorless to yellow. The color gradually deepens, and finally becomes orange-red. After reacting for 8-12 hours, methanol and most of the water are removed by distillation under reduced pressure in a water bath (do not use an oil bath to prevent the temperature from being too high). After the residual liquid is cooled, add sodium carbonate for shaking, add sodium chloride for salting out, and extract with diethyl ether for 3 to 4 times until the water layer turns yellow. Combine the ether extracts, dry them with anhydrous calcium chloride, distill off the ether under reduced pressure in a water bath, and cool and solidify to obtain an orange-red solid poly-4-methacrylic acid-2,2,6,6-tetramethylpiperidine-1- Nitroxide free radical (PTMA) was recrystallized in n-hexane to obtain pink PTMA with nitroxide stable free radical in the side chain, and the yield was 98%.

(7) The structure of PTMA

Use sodium metal as a catalyst in benzene and xylene solution to prepare MTMP from HTMP and MMA by transesterification. Figure 4 infrared spectrum shows that the functional groups of MTMP are at 3400cm ^-1 (NH), 1630cm ^-1 (C=C), 1705cm There is an absorption peak at ^-1 (C=O); the functional group of PMTMP has an absorption peak at 3400cm ^-1 (NH), 1720cm ^-1 (C=O), and the absorption peak at 1630cm ^-1 (C=C) disappears ; The functional groups of PTMA have absorption peaks at 1720cm ^-1 (C=O), 1360cm ^-1 (NO·), while the absorption peaks of functional groups (NH) disappear at 3400cm ^-1 .

The ultraviolet-visible spectrum of PTMA shows that PTMA has absorption peaks at 230-250nm and 410-450nm (N-O·) as shown in Figure 5 .

The ESR spectrum of PTMA is shown in Figure 6, and PTMA has a broad single peak. The spin number in 16 mg PTMA was quantitatively detected by ESR to be 4.0222×10 ²² , and there were 1.00 nitrogen-oxygen stable free radicals on each monomer in the polymer PTMA.

Example 2

The PTMA obtained by embodiment 1 is used as lithium secondary battery organic cathode material

(a) Assembly of battery

The battery uses a PTMA aluminum foil electrode as the positive electrode and a metal lithium sheet as the negative electrode. The electrolyte solution is 1mol·L ^-1 LiPF ₆ /EC-DMC (volume ratio 1:1). The assembly of the cells was carried out in an argon-filled glove box.

(b) Working principle of PTMA/lithium secondary battery

The working principle of PTMA/lithium secondary battery refers to its charging and discharging principle, which is the same as that of lithium secondary battery. According to the ESR spectra of oxidized PTMA (4.2V) and reduced PTMA (3V) and the charge-discharge curve and CV curve of PTMA, the oxidation peak of PTMA at E _{a, p} = 3.644V is that the ON group of PTMA is Oxidation loses an electron and transforms into an O=N group to form a positive ion salt with the electrolyte anion, which corresponds to the charging process of the battery; the reduction peak at E _{c, p} = 3.581V is the O=N group of PTMA that is The reduction obtains an electron into an ON group, which corresponds to the discharge process of the battery, and the mutual transformation of the ON group and the O=N group is a reversible redox reaction. The charge-discharge cycle process of the free radical polymer electrode is accompanied by the occurrence of this redox reaction, thereby completing the mutual conversion between chemical energy and electrical energy. During the charging and discharging process of the free radical polymer, the positive electrode reaction that occurs is shown in Figure 6:

The PTMA/lithium secondary battery uses metal lithium as the negative electrode. During the charge and discharge cycle, the metal lithium dissolves in the discharge reaction, and lithium is precipitated in the charge reaction. The negative electrode reaction is shown in Figure 7:

The overall reaction of the PTMA/lithium secondary battery is shown in Figure 8:

(c) Electrochemical performance of PTMA

Fig. 9 is the charge and discharge curve of PTMA/lithium battery. The weight of PTMA in the button cell is 19.2mg, and it is charged and discharged between 2.5V and 4.0V with a constant current of 0.3mA. (0.2C) The maximum discharge specific capacity at constant current discharge is 78.4mAh·g ^-1 . In the redox process, each free radical in the PTMA molecule transfers one electron, its theoretical specific capacity is 111mAh·g ^-1 , and the actual specific capacity of PTMA is 70.6% of the theoretical specific capacity. Calculated from the charge-discharge curve of the PTMA button cell, its coulombic efficiency is about 95% (second cycle). The charge-discharge curve of PTMA/lithium button battery also shows that the charge curve of the battery has a very stable platform at 3.65V and the discharge curve at 3.56V (vs. Li/Li ⁺ ).

(d) Cycle life of PTMA

Figure 10 is a cycle curve of charging and discharging a PTMA/lithium button battery at a constant current of 1.5mA (1C) between 2.5V and 4.0V. After 300 charge-discharge cycles, the discharge specific capacity of the battery is only attenuated by 2.0% relative to the maximum discharge specific capacity. This is mainly due to the electrostatic resistance and conjugation effect of the adjacent methyl groups around the nitrogen-oxygen bond in the PTMA molecule make the nitrogen-oxygen free radicals very stable, and the molecular structure remains unchanged during the charge-discharge cycle (ie, redox). Unlike organic sulfides, the S-S bond will be broken during the charge-discharge cycle, making them become small molecular substances dissolved in the electrolyte or the structure will be destroyed, resulting in capacity fading, and when the inorganic layered transition metal oxide is charged and discharged The intercalation and intercalation of lithium ions in metal oxides destabilizes the structure and leads to poor cycle performance.

(e) High current charge and discharge performance of PTMA

Figures 11 and 12 are the charge and discharge curves of the PTMA button cell at the same discharge rate under different charge current conditions. It can be seen from Figures 11 and 12 that when charged at 0.2C, 0.5C and 1C, the discharge specific capacities of PTMA are 78.4mAh·g-1, 76.6mAh·g-1 and 75.2mAh·g-1, respectively. However, as the charging current continues to increase, the discharge specific capacity decreases faster. The discharge specific capacity is 72.8mAh·g-1 and 70.6mAh·g-1 when charging at 2C and 6C. When the charging current increases to 10C , the discharge specific capacity has dropped to 67.1mAh·g-1, which is 85.5% of 0.2C charging, that is, 85.5% of the battery capacity can be fully charged in 6 minutes at a charging speed of 10C.

Figure 13 is the charge and discharge curves of the PTMA button battery at different discharge rates under the same charge current condition. It can be seen from Figure 13 that when discharging at 0.2C, the average discharge voltage is 3.56V, and when it increases from 0.2C to 2C (the average discharge voltage is 3.54V), the average discharge voltage does not change much, only decreasing by 0.02V. However, as the discharge current continues to increase, the average discharge voltage decreases rapidly. The average discharge voltages of 4C, 6C and 8C discharges are 3.51V, 3.46V and 3.41V respectively. When the discharge current increases to 10C, the average discharge voltage The voltage dropped to 3.33V, 93.5% of what it was at 0.2C discharge.

(f) Electrochemical performance of PTMA batteries with carbon as anode

Using PTMA as the positive electrode, carbon as the negative electrode, and 1mol L-1LiPF6/EC-DMC (volume ratio 1:1) as the electrolyte, a PTMA battery was assembled in a glove box filled with argon gas. The charge and discharge curves are shown in Figure 14. Show. The charge and discharge curves of PTMA batteries show that the charge curve has a very stable platform at 3.54V (vs. Li/Li+) and the discharge curve at 3.50V (vs. Li/Li+). When PTMA is charged and discharged at a constant current of 0.2C, its maximum charge specific capacity is 78.7mAh g-1, and its maximum discharge specific capacity is 73.2mAh g-1. Its coulombic efficiency is calculated from the charge-discharge curve of the PTMA button battery. About 93.0% (2nd cycle).

However, when the metal lithium sheet is used as the negative electrode, the maximum discharge specific capacity of the PTMA button battery is 78.4mAh·g-1, and the Coulombic efficiency is 95% (the second cycle). The charge and discharge curves of PTMA batteries have a very stable platform at 3.65V and 3.56V respectively, and the charge and discharge curves are shown in Figure 14. Comparing the charge-discharge curves of PTMA button batteries when metal lithium sheets and carbon are used as negative electrodes, when carbon is used as negative electrodes, the charge-discharge capacity and charge-discharge platform of PTMA batteries are both reduced.

The cycle curve of the PTMA two-electrode button cell with carbon or metallic lithium as the negative electrode is shown in Figure 15. The PTMA button battery is charged and discharged between 2.5V and 4.0V with a constant current of 1C. After 300 charge and discharge cycles, the discharge specific capacity of the battery is changed from 75.2mAh·g-1 to 75.2mAh g reduced to 73.8mAh·g-1, the discharge specific capacity decayed by 2%, and when carbon was used as the negative electrode, the discharge specific capacity of the battery was reduced from the second 69.0mAh·g-1 to 67.9mAh·g-1, and the discharge ratio The capacity decay was only 1.6%. Therefore, the cycle performance of PTMA batteries is better when carbon is used as the negative electrode and metal lithium is used as the negative electrode.

Some abbreviations in the manual:

PTMA (poly(2,2,6,6-tetramethyl-piperidinyloxy methacrylate), PTMA for short).

PMTMP (poly-4-methacryloxy-2,2,6,6-tetramethylpiperdine, poly-4-methacryloxy-2,2,6,6-tetramethyl-piperdine, referred to as PMTMP).

MTMP (4-methacryloxy-2,2,6,6-tetramethylpiperidine, 4-methacryloxy-2,2,6,6-tetramethylpiperdine, MTMP for short).

HTMP (2,2,6,6-tetramethyl-4-hydroxypiperidine, 2,2,6,6-tetramethyl-4-piperidine, HTMP for short).

MMA (methyl methacrylate, methyl methacrylate, referred to as MMA).

Claims (7)

1. lithium secondary battery organic free radical polyalcohol PTMA positive electrode material is synthetic, and it is characterized in that: the preparation of described material may further comprise the steps:

(1) be presoma with HTMP and MMA, as stopper, magnesium methylate or sodium Metal 99.5 adopt and optimize the synthetic preparation of transesterify MTMP as catalyzer with Resorcinol or metallic copper;

(2) with the MTMP purifying that obtains, be monomer with MTMP, AIBN is that initiator prepares polymer P MTMP by the free radical mass polymerization;

(3) presoma PMTMP uses sodium wolframate-hydrogen peroxide-disodium ethylene diamine tetraacetate as oxygenant in methanol solution, makes polymer P MTMP be oxidized to the free radical polyalcohol PTMA that side chain has living free radical polymerization.

2. synthesizing of lithium secondary battery organic free radical polyalcohol PTMA positive electrode material according to claim 1, it is characterized in that: in (1) step, HTMP and excessive MMA are added in the reaction separation column, be heated to boiling, the temperature of capital rises to 95-105 ℃ gradually, kept under this temperature 10-20 minute, reaction is finished again; Excessive MMA is removed in underpressure distillation, continues underpressure distillation, collects 94～96 ℃, the cut of 0.4～0.5KPa, and it is MTMP.

3. synthesizing of lithium secondary battery organic free radical polyalcohol PTMA positive electrode material according to claim 1, it is characterized in that: in (2) step, MTMP, initiator A IBN, solvent toluene are added in the reactor vacuum outgas, charge into argon gas, polyreaction 10-14h isolates polymkeric substance under 55-65 ℃ temperature, and vacuum-drying gets the white powder solid, be poly-4-methacrylic acid-2,2,6,6-tetramethyl piperidine alcohol ester (PMTMP).

4. synthesizing of lithium secondary battery organic free radical polyalcohol PTMA positive electrode material according to claim 1, it is characterized in that: in (3) step, the oxidization time of polymer P MTMP is 30～40h.

5. synthesizing of lithium secondary battery organic free radical polyalcohol PTMA positive electrode material according to claim 1, it is characterized in that: in (2) step, the purifying of described MTMP is to filter with the sand core funnel earlier; Under agitation, filtrate is splashed in the water of 6-10 times of volume, filter precipitate, the washing back is air-dry, and room temperature vacuum-drying gets white crystals to constant weight.

6. synthesizing of lithium secondary battery organic free radical polyalcohol PTMA positive electrode material according to claim 1, it is characterized in that: in (1) step, described magnesium methylate is to make raw material with magnesium powder and methyl alcohol, iodine is made initiator, behind reaction 1～2h, by the time there is not hydrogen to emit, reaction solution becomes white paste, obtains magnesium methylate.

7. the application of lithium secondary battery organic free radical polyalcohol PTMA is characterized in that: PTMA is applied to lithium secondary battery as positive electrode material.

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