CN113603892A - Elastic polymer binder applied to silicon electrode of ion battery and preparation method thereof - Google Patents
Elastic polymer binder applied to silicon electrode of ion battery and preparation method thereof Download PDFInfo
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Abstract
The invention discloses an elastic polymer binder applied to an ionic cell silicon electrode and a preparation method thereof, and the preparation method comprises 5 steps of preparing a novel hard long-chain compound, preparing bromine-a novel hard long-chain-bromine compound, preparing xanthate-a novel hard long-chain-xanthate compound, preparing a soft-segment and hard-segment combined compound and preparing an elastic polymer binder The conductive agent and the current collector are bonded together, so that the coulombic efficiency and the electrochemical stability of the silicon substrate are improved.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to an elastic polymer binder applied to a silicon electrode of an ion battery and a preparation method thereof.
Background
The theoretical capacity of a graphite cathode commonly adopted by a lithium ion battery is only 372mAh/g, the actual capacity is close to the limit, the improvement is difficult to achieve, the requirement of an electric automobile for higher and higher energy density of the battery is difficult to meet, the theoretical capacity of silicon at normal temperature is 3580mAh/g, the theoretical capacity of SiO is larger than 2000mAh/g and is far larger than the capacity of graphite, but the volume change of a silicon-based electrode material in the charging and discharging process is huge, the active material is easy to pulverize and fall off, the rapid attenuation of the battery capacity is finally caused, and the commercial application of the silicon-based electrode material is further limited.
The binder is used as one of the necessary materials for manufacturing the battery, the content of the binder in the electrode is very small (1.5-3%), the cost of the binder accounts for 1-3% of the total cost of the battery, but the binder has an irreplaceable effect, the main function of the binder is to bind an active substance, a conductive agent and a current collector together so as to shorten a lithium ion transmission path and stabilize the structure of the electrode material, and the binders with different properties can directly influence the specific capacity, the coulombic efficiency, the stability of electrochemical performance and the like of the battery.
Among the existing silicon-based electrodes, the most widely used system is an SBR/CMC mixture, which acts as a buffer to buffer volume changes of silicon during charge and discharge, but when the silicon content exceeds 10 wt%, it is difficult for the conventional binder to maintain the integrity of the electrode due to the large volume change of silicon.
Patent document CN201811446118 discloses a carbon-silicon negative electrode plate using a high-viscosity lithium binder and a preparation method thereof, wherein the carbon-silicon negative electrode plate comprises the following components in parts by weight: 1-3 parts of CMC Li, 0.5-1 part of modified SBR, 0.1-1 part of carbon nano tube, 90-98 parts of carbon silica sol, 0.5-5 parts of viscosity regulator and 20-60 parts of deionized water; the silicon-carbon negative electrode material fully combines the high lithium intercalation capacity of silicon and the excellent mechanical property and the conductive property of carbon, the mechanical elasticity of the carbon material can buffer the huge volume expansion of silicon, and meanwhile, the high electronic conductivity also can supplement the high lithium intercalation capacity of silicon, so that the silicon-carbon composite negative electrode material has higher specific capacity, the first discharge capacity is higher, the cycle efficiency is high, and the cycle stability is greatly improved.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide an elastic polymer binder applied to a silicon electrode of an ion battery and a preparation method thereof, and solves the technical problems that the integrity of an electrode plate is difficult to maintain and the internal adhesion with a silicon electrode active material layer is poor when the silicon content of the traditional electrode binder is high.
In order to achieve the purpose, the invention adopts the following technical scheme:
a preparation method of an elastic polymer binder applied to an ion battery silicon electrode comprises the following steps:
(1) preparation of bromine-novel hard long chain-bromine complex: uniformly mixing the novel hard long-chain compound, 2-ethyl-2-oxazoline and acetonitrile, degassing, sealing, heating for reaction, and after the reaction is finished, carrying out precipitation separation and vacuum drying on a reaction product to obtain a bromine-novel hard long-chain-bromine compound;
(2) preparing xanthate-novel hard long chain-xanthate compound: adding bromine-novel hard long chain-bromine compound and ethyl xanthate into an acetonitrile solvent, uniformly mixing to obtain a mixed solution, reacting the mixed solution at room temperature in a nitrogen atmosphere, filtering a reaction product after the reaction is finished, distilling the reaction product under reduced pressure, dissolving the reaction product in dichloromethane, filtering, washing by using a saturated sodium chloride aqueous solution, drying, filtering, distilling, precipitating in diethyl ether to obtain a polymer, and drying the polymer at room temperature in vacuum to obtain the xanthate-novel hard long chain-xanthate compound;
(3) preparing a soft segment and hard segment combined compound: dissolving the xanthate-novel hard long chain-xanthate compound in a tetrahydrofuran solvent, adding n-butylamine, reacting at room temperature, and after the reaction is finished, precipitating, filtering and drying a reaction product in vacuum to obtain a soft-segment and hard-segment combined compound;
(4) preparation of the elastomeric polymeric binder: dissolving chitosan in a mixed solution of N, N-dimethylformamide and acetic acid, adding a soft-segment combination compound and a catalyst, stirring and reacting at 4 ℃ for 20-24h, and after the reaction is finished, freeze-drying a reaction product to obtain the elastic polymer binder.
Preferably, in the step (1), the mass ratio of the novel hard long-chain compound, the 2-ethyl-2-oxazoline and the acetonitrile is 4-5:8-12: 20-40.
Preferably, in the step (1), the heating reaction temperature is 75-80 ℃, and the heating reaction time is 20-24 h.
Preferably, in the step (2), the mass ratio of the bromine-novel hard long-chain bromine complex to the ethyl xanthate is 43:29-64, and the ethyl xanthate is sodium ethyl xanthate or potassium ethyl xanthate.
Preferably, in the step (2), the reaction time is 15-18h, and the vacuum drying time is 20-28 h.
Preferably, in the step (3), the mass ratio of the xanthate-novel hard long chain-xanthate compound to n-butylamine is 4-5:2-4, the reaction time is 4-6h, and the vacuum drying time is 20-28 h.
Preferably, in the step (4), the mass ratio of the chitosan, the soft and hard segment combined compound and the catalyst is 1:1:0.05-0.1, the catalyst is a mixture of 1-ethyl-3- (dimethylaminopropyl carbodiimide) and N-hydroxysuccinimide, and the mass ratio of the 1-ethyl-3- (dimethylaminopropyl carbodiimide) and the N-hydroxysuccinimide is 4: 1.
Preferably, in the step (1), the preparation method of the novel hard long-chain compound comprises the following steps: adding 4, 4-bis (3, 5-dibromo-4-hydroxybenzene) valeric acid, a catalyst and diphenylmethane isocyanate into a tetrahydrofuran solvent in a nitrogen atmosphere, stirring for 20-40min at the temperature of 60-80 ℃, and then carrying out vacuum drying to obtain the novel hard long-chain compound.
Preferably, the mass ratio of the 4, 4-bis (3, 5-dibromo-4-hydroxyphenyl) pentanoic acid to the catalyst to the diphenylmethane isocyanate is 6-7:0.01-0.03:2-3, and the catalyst is dibutyltin dilaurate or stannous octoate.
The invention also provides the elastic polymer binder which is obtained by the preparation method and is applied to the silicon electrode of the ion battery.
Compared with the prior art, the invention has the following beneficial effects:
(1) the invention provides an elastic polymer adhesive applied to an ion battery silicon electrode and a preparation method thereof, the invention polymerizes 4, 4-bis (3, 5-dibromo-4-hydroxybenzene) valeric acid and diphenylmethane isocyanate into a novel hard long-chain compound under an organic tin catalyst, then synthesizes bromine-base-end functionalized poly (2-ethyl-2-oxazoline) by taking the novel hard long-chain compound as an initiator, then reacts with ethylsulfonate to obtain a xanthate-novel hard long-chain-xanthate compound, then uses n-butylamine to crack the xanthate-novel hard long-chain-xanthate compound, is oxidized under the air to form a disulfide bond, thereby connecting the hard long chain and the reversible soft segment to obtain a soft segment and hard segment combined compound, and finally mixes the soft segment and soft segment combined compound with chitosan, the soft and hard segment combined elastic polymer binder is obtained by combining carboxyl on the hard long chain of the soft and hard segment combined compound with amino on chitosan through an amide reaction under the action of a catalyst.
(2) The invention provides an elastic polymer binder applied to a silicon electrode of an ion battery and a preparation method thereof, the binder provided by the invention contains a soft-segment structure, wherein a hard long chain has a certain binding force on the volume expansion of silicon during lithium intercalation, and sulfide is introduced into the end group of the soft chain.
(3) The invention further improves the adhesive force of the adhesive by introducing chitosan, can stably bond active substances, conductive agents and current collectors together, shortens the transmission path of lithium ions, and improves the coulombic efficiency and the electrochemical stability of silicon substrates.
Detailed Description
The present invention will be described in more detail with reference to specific preferred embodiments, but the present invention is not limited to the following embodiments.
It should be noted that, unless otherwise specified, the chemical reagents involved in the present invention are commercially available.
Example 1
A preparation method of an elastic polymer binder applied to an ion battery silicon electrode comprises the following steps:
(1) preparing a novel hard long-chain compound: under the atmosphere of nitrogen, 6.2g of 4, 4-bis (3, 5-dibromo-4-hydroxybenzene) pentanoic acid, 0.01g of dibutyltin dilaurate and 2.5g of diphenylmethane isocyanate are added into 100mL of tetrahydrofuran solvent, stirred for 30min at 70 ℃, and then vacuum-dried for 72h at 60 ℃ to obtain a novel hard long-chain compound;
(2) preparation of bromine-novel hard long chain-bromine complex: 4.3g of the novel rigid long-chain compound, 8.5g of 2-ethyl-2-oxazoline and 30g of acetonitrile are filled into a pre-dried polymerization tube, the reaction mixture is degassed through three freezing-pump-thawing cycles and then sealed, the reaction mixture is heated to 75 ℃ to react for 20 hours, after the reaction is finished, ether is added to precipitate and separate the residual polymer product, and the product is dried for 24 hours at room temperature through a vacuum oven, thus obtaining the bromine-novel rigid long-chain-bromine compound;
(3) preparing xanthate-novel hard long chain-xanthate compound: adding 4.3g of bromine-novel hard long chain-bromine compound and 3g of sodium ethyl xanthate into 50g of acetonitrile solvent, uniformly mixing to obtain a mixed solution, reacting the mixed solution at room temperature for 16h under the nitrogen atmosphere, filtering a product obtained by the reaction to remove salt, removing the solvent under reduced pressure after the reaction is finished, dissolving the product in dichloromethane, filtering, washing with saturated sodium chloride aqueous solution for 3 times, drying the obtained organic phase with anhydrous sodium sulfate, filtering, removing the solvent with a rotary evaporator, precipitating the compound in diethyl ether, and drying the compound in a vacuum oven at room temperature for 24h to obtain the xanthate-novel hard long chain-xanthate compound;
(4) preparing a soft segment and hard segment combined compound: dissolving 4.3g of xanthate-novel hard long chain-xanthate compound in 100g of tetrahydrofuran solvent, adding 2g of n-butylamine, stirring the mixture at room temperature for reaction for 6 hours, precipitating the compound in ether after the reaction is finished, filtering, and drying the obtained compound in a vacuum oven at room temperature for 24 hours to obtain a soft and hard segment combined compound;
(5) preparation of the elastomeric polymeric binder: dissolving 5g of chitosan in a mixed solution of 30mLN, N-dimethylformamide and acetic acid, wherein the volume ratio of N, N-dimethylformamide to acetic acid is 2:1, then adding 5g of a soft segment-bound complex, 0.4g of 1-ethyl-3- (dimethylaminopropyl carbodiimide) and 0.1g of N-hydroxysuccinimide, stirring for 24h at 4 ℃, and after the reaction is finished, freeze-drying the reaction product for 72h at-55 ℃ to obtain the elastic polymer binder.
Example 2
A preparation method of an elastic polymer binder applied to an ion battery silicon electrode comprises the following steps:
(1) preparing a novel hard long-chain compound: under the atmosphere of nitrogen, 6.4g of 4, 4-bis (3, 5-dibromo-4-hydroxyphenyl) pentanoic acid, 0.02g of dibutyltin dilaurate and 2g of diphenylmethane isocyanate are added into 100mL of tetrahydrofuran solvent, stirred for 30min at 70 ℃, and then vacuum-dried for 72h at 60 ℃ to obtain a novel hard long-chain compound;
(2) preparation of bromine-novel hard long chain-bromine complex: 4.3g of the novel rigid long-chain compound, 10g of 2-ethyl-2-oxazoline and 30g of acetonitrile are filled into a pre-dried polymerization tube, the reaction mixture is degassed through three freezing-pump-thawing cycles and then sealed, the reaction mixture is heated to 75 ℃ to react for 20 hours, after the reaction is finished, ether is added to precipitate and separate the residual polymer product, and the product is dried for 24 hours at room temperature through a vacuum oven, thus obtaining the bromine-novel rigid long-chain-bromine compound;
(3) preparing xanthate-novel hard long chain-xanthate compound: adding 4.3g of bromine-novel hard long chain-bromine compound and 3.2g of sodium ethyl xanthate into 50g of acetonitrile solvent, uniformly mixing to obtain a mixed solution, reacting the mixed solution at room temperature for 16h under the nitrogen atmosphere, filtering a product obtained by the reaction to remove salt after the reaction is finished, removing the solvent under reduced pressure, dissolving the product in dichloromethane, filtering, washing with saturated sodium chloride aqueous solution for 3 times, drying the obtained organic phase with anhydrous sodium sulfate, filtering, removing the solvent with a rotary evaporator, precipitating the compound in diethyl ether, and drying the compound in a vacuum oven at room temperature for 24h to obtain the xanthate-novel hard long chain-xanthate compound;
(4) preparing a soft segment and hard segment combined compound: dissolving 4.3g of xanthate-novel hard long chain-xanthate compound in 100g of tetrahydrofuran solvent, adding 2.3g of n-butylamine, stirring the mixture at room temperature for reaction for 5 hours, precipitating the compound in ether after the reaction is finished, filtering, and drying the obtained compound in a vacuum oven at room temperature for 24 hours to obtain a soft and hard segment combined compound;
(5) preparation of the elastomeric polymeric binder: dissolving 4g of chitosan in a mixed solution of 30mLN, N-dimethylformamide and acetic acid, wherein the volume ratio of N, N-dimethylformamide to acetic acid is 2:1, then adding 4g of a soft segment-bound complex, 0.2g of 1-ethyl-3- (dimethylaminopropyl carbodiimide) and 0.05g of N-hydroxysuccinimide, stirring for 24h at 4 ℃, and after the reaction is finished, freeze-drying the reaction product for 72h at-55 ℃ to obtain the elastic polymer binder.
Example 3
A preparation method of an elastic polymer binder applied to an ion battery silicon electrode comprises the following steps:
(1) preparing a novel hard long-chain compound: under the atmosphere of nitrogen, 6.5g of 4, 4-bis (3, 5-dibromo-4-hydroxybenzene) pentanoic acid, 0.025g of dibutyltin dilaurate and 2.2g of diphenylmethane isocyanate are added into 100mL of tetrahydrofuran solvent, stirred for 35min at 60 ℃, and then vacuum-dried for 72h at 60 ℃ to obtain a novel hard long-chain compound;
(2) preparation of bromine-novel hard long chain-bromine complex: 4.3g of the novel rigid long-chain compound, 9g of 2-ethyl-2-oxazoline and 35g of acetonitrile are filled into a pre-dried polymerization tube, the reaction mixture is degassed through three freezing-pump-thawing cycles and then sealed, the reaction mixture is heated to 75 ℃ to react for 20 hours, after the reaction is finished, ether is added to precipitate and separate the residual polymer product, and the product is dried for 24 hours at room temperature through a vacuum oven, thus obtaining the bromine-novel rigid long-chain-bromine compound;
(3) preparing xanthate-novel hard long chain-xanthate compound: adding 4.3g of bromine-novel hard long chain-bromine compound and 3.8g of sodium ethyl xanthate into 50g of acetonitrile solvent, uniformly mixing to obtain a mixed solution, reacting the mixed solution at room temperature for 16h under the nitrogen atmosphere, filtering a product obtained by the reaction to remove salt after the reaction is finished, removing the solvent under reduced pressure, dissolving the product in dichloromethane, filtering, washing with saturated sodium chloride aqueous solution for 3 times, drying the obtained organic phase with anhydrous sodium sulfate, filtering, removing the solvent with a rotary evaporator, precipitating the compound in diethyl ether, and drying the compound in a vacuum oven at room temperature for 24h to obtain the xanthate-novel hard long chain-xanthate compound;
(4) preparing a soft segment and hard segment combined compound: dissolving 4.3g of xanthate-novel hard long chain-xanthate compound in 100g of tetrahydrofuran solvent, adding 2.8g of n-butylamine, stirring the mixture at room temperature for reaction for 6 hours, precipitating the compound in ether after the reaction is finished, filtering, and drying the obtained compound in a vacuum oven at room temperature for 26 hours to obtain a soft and hard segment combined compound;
(5) preparation of the elastomeric polymeric binder: dissolving 5g of chitosan in a mixed solution of 30mLN, N-dimethylformamide and acetic acid, wherein the volume ratio of N, N-dimethylformamide to acetic acid is 2:1, then adding 5g of a soft segment and hard segment combined compound, 0.32g of 1-ethyl-3- (dimethylaminopropyl carbodiimide) and 0.08g of N-hydroxysuccinimide, stirring for 24h at 4 ℃, and after the reaction is finished, freeze-drying the reaction product for 72h at-55 ℃ to obtain the elastic polymer binder.
Example 4
A preparation method of an elastic polymer binder applied to an ion battery silicon electrode comprises the following steps:
(1) preparing a novel hard long-chain compound: under the atmosphere of nitrogen, 6.8g of 4, 4-bis (3, 5-dibromo-4-hydroxybenzene) pentanoic acid, 0.03g of dibutyltin dilaurate and 2.5g of diphenylmethane isocyanate are added into 100mL of tetrahydrofuran solvent, stirred for 25min at 80 ℃, and then vacuum-dried for 72h at 60 ℃ to obtain a novel rigid long-chain compound;
(2) preparation of bromine-novel hard long chain-bromine complex: 4.3g of the novel rigid long-chain compound, 12g of 2-ethyl-2-oxazoline and 40g of acetonitrile are filled into a pre-dried polymerization tube, the reaction mixture is degassed through three freezing-pump-thawing cycles and then sealed, the reaction mixture is heated to 75 ℃ to react for 20 hours, after the reaction is finished, ether is added to precipitate and separate the residual polymer product, and the product is dried for 24 hours at room temperature through a vacuum oven, thus obtaining the bromine-novel rigid long-chain-bromine compound;
(3) preparing xanthate-novel hard long chain-xanthate compound: adding 4.3g of bromine-novel hard long chain-bromine compound and 5g of sodium ethyl xanthate into 50g of acetonitrile solvent, uniformly mixing to obtain a mixed solution, reacting the mixed solution at room temperature for 16h under the nitrogen atmosphere, filtering a product obtained by the reaction to remove salt, removing the solvent under reduced pressure after the reaction is finished, dissolving the product in dichloromethane, filtering, washing with saturated sodium chloride aqueous solution for 3 times, drying the obtained organic phase with anhydrous sodium sulfate, filtering, removing the solvent with a rotary evaporator, precipitating the compound in diethyl ether, and drying the compound in a vacuum oven at room temperature for 24h to obtain the xanthate-novel hard long chain-xanthate compound;
(4) preparing a soft segment and hard segment combined compound: dissolving 4.5g of xanthate-novel hard long chain-xanthate compound in 100g of tetrahydrofuran solvent, adding 3.5g of n-butylamine, stirring the mixture at room temperature for reaction for 6h, precipitating the compound in ether after the reaction is finished, filtering, and drying the obtained compound in a vacuum oven at room temperature for 28h to obtain a soft and hard segment combined compound;
(5) preparation of the elastomeric polymeric binder: dissolving 5g of chitosan in a mixed solution of 30mLN, N-dimethylformamide and acetic acid, wherein the volume ratio of N, N-dimethylformamide to acetic acid is 2:1, then adding 5g of a soft segment-bound complex, 0.4g of 1-ethyl-3- (dimethylaminopropyl carbodiimide) and 0.1g of N-hydroxysuccinimide, stirring for 24h at 4 ℃, and after the reaction is finished, freeze-drying the reaction product for 72h at-55 ℃ to obtain the elastic polymer binder.
Comparative example 1
A preparation method of a binder applied to an ion battery silicon electrode comprises the following steps:
(1) preparation of bromine-soft chain-bromine complex: loading 1.7g of tribromomethylbenzene, 15g of 2-ethyl-2-oxazoline and 50mL of acetonitrile into a pre-dried polymerization tube, degassing the reaction mixture through three freeze-pump-thaw cycles, sealing, heating the reaction mixture to 75 ℃ for reaction for 20h, adding diethyl ether after the reaction is finished, precipitating and separating residual polymer products, and drying at room temperature for 24h through a vacuum oven to obtain a bromine-soft chain-bromine compound;
(2) preparing a xanthate-soft chain-xanthate compound: adding 4.3g of bromine-soft chain-bromine compound and 3.8g of sodium ethyl xanthate into 50g of acetonitrile solvent, uniformly mixing to obtain a mixed solution, reacting the mixed solution at room temperature for 16h under the nitrogen atmosphere, filtering a product obtained by the reaction to remove salt after the reaction is finished, removing the solvent under reduced pressure, dissolving the product in dichloromethane, filtering, washing with saturated sodium chloride aqueous solution for 3 times, drying the obtained organic phase with anhydrous sodium sulfate, filtering, removing the solvent with a rotary evaporator, precipitating the compound in diethyl ether, and drying the compound in a vacuum oven at room temperature for 24h to obtain the xanthate-soft chain-xanthate compound;
(3) preparing a soft segment and hard segment combined compound: dissolving 4.3g of xanthate-soft chain-xanthate compound in 100g of tetrahydrofuran solvent, adding 2.8g of n-butylamine, stirring the mixture at room temperature for reaction for 6 hours, precipitating the compound in ether after the reaction is finished, filtering, and drying the obtained compound in a vacuum oven at room temperature for 26 hours to obtain a reversible soft chain compound;
(4) preparation of the polymeric binder: dissolving 5g of chitosan in a mixed solution of 30mLN, N-dimethylformamide and acetic acid, wherein the volume ratio of N, N-dimethylformamide to acetic acid is 2:1, then adding 5g of reversible soft chain compound, 0.32g of 1-ethyl-3- (dimethylaminopropyl carbodiimide) and 0.08g of N-hydroxysuccinimide, stirring for 24h at 4 ℃, and after the reaction is finished, freezing and drying the reaction product for 72h at-55 ℃ to obtain the polymer binder.
Comparative example 2
A preparation method of a binder applied to an ion battery silicon electrode comprises the following steps:
(1) preparing a novel hard long-chain compound: under the atmosphere of nitrogen, 6.5g of 4, 4-bis (3, 5-dibromo-4-hydroxybenzene) pentanoic acid, 0.025g of dibutyltin dilaurate and 2.2g of diphenylmethane isocyanate are added into 100mL of tetrahydrofuran solvent, stirred for 35min at 60 ℃, and then vacuum-dried for 72h at 60 ℃ to obtain a novel hard long-chain compound;
(2) preparation of bromine-novel hard long chain-bromine complex: 4.3g of the novel rigid long-chain compound, 9g of 2-ethyl-2-oxazoline and 35g of acetonitrile are filled into a pre-dried polymerization tube, the reaction mixture is degassed through three freezing-pump-thawing cycles and then sealed, the reaction mixture is heated to 75 ℃ to react for 20 hours, after the reaction is finished, ether is added to precipitate and separate the residual polymer product, and the product is dried for 24 hours at room temperature through a vacuum oven, thus obtaining the bromine-novel rigid long-chain-bromine compound;
(3) preparing xanthate-novel hard long chain-xanthate compound: adding 4.3g of bromine-novel hard long chain-bromine compound and 3.8g of sodium ethyl xanthate into 50g of acetonitrile solvent, uniformly mixing to obtain a mixed solution, reacting the mixed solution at room temperature for 16h under the nitrogen atmosphere, filtering a product obtained by the reaction to remove salt after the reaction is finished, removing the solvent under reduced pressure, dissolving the product in dichloromethane, filtering, washing with saturated sodium chloride aqueous solution for 3 times, drying the obtained organic phase with anhydrous sodium sulfate, filtering, removing the solvent with a rotary evaporator, precipitating the compound in diethyl ether, and drying the compound in a vacuum oven at room temperature for 24h to obtain the xanthate-novel hard long chain-xanthate compound;
(4) preparing a soft segment and hard segment combined composite binder: dissolving 4.3g of xanthate-novel hard long chain-xanthate compound in 100g of tetrahydrofuran solvent, adding 2.8g of n-butylamine, stirring the mixture at room temperature for reaction for 6h, precipitating the compound in ether after the reaction is finished, filtering, and drying the obtained compound in a vacuum oven at room temperature for 26h to obtain the soft and hard segment combined compound binder.
The binders prepared in examples 1 to 4 and comparative examples 1 to 2 were respectively prepared into mixed slurry with Si/C and conductive carbon black, the mixed slurry was cast on a copper foil of an electrode using a doctor blade coating method, the electrode was dried at 130 ℃ for 4 hours and then at 60 ℃ for 12 hours in a vacuum oven to obtain an electrode, the electrodes obtained from the binders prepared in examples 1 to 4 and comparative examples 1 to 2 were subjected to electrochemical performance testing, the constant current density was 0.1A/g for three cycles before cycle performance, the current density for the subsequent cycles was 0.2A/g, and the battery capacity was tested when the cycle was 300 times, and the experimental results are shown in the following table:
as can be seen from the table, the binder prepared in this example still maintains a relatively high battery capacity when the silicon content reaches 16 wt%, and the battery capacity increases with the increase of the silicon content, comparative example 1 does not introduce a rigid long-chain compound, so that there is no restriction on the volume change of silicon, after 300 cycles, the active material undergoes cracking or pulverization due to a large volume change many times, so that an SEI film is continuously formed between the active lithium and the newly exposed silicon surface, the integrity of the electrode cannot be maintained, and when the silicon content exceeds 10 wt%, this phenomenon is more obvious, so that the capacity of silicon is obviously reduced, comparative example 2 does not introduce chitosan, when the silicon content exceeds 10 wt%, the capacity is obviously reduced, which means that the introduction of chitosan can improve the adhesive force of the binder, and the active material, the conductive agent and the current collector are bonded together, the transmission path of lithium ions is shortened, and the coulombic efficiency and the electrochemical stability of the silicon substrate are improved.
Finally, it is to be noted that: the above examples do not limit the invention in any way. It will be apparent to those skilled in the art that various modifications and improvements can be made to the present invention. Accordingly, any modification or improvement made without departing from the spirit of the present invention is within the scope of the claimed invention.
Claims (10)
1. A preparation method of an elastic polymer binder applied to an ion battery silicon electrode is characterized by comprising the following steps:
(1) preparation of bromine-novel hard long chain-bromine complex: uniformly mixing the novel hard long-chain compound, 2-ethyl-2-oxazoline and acetonitrile, degassing, sealing, heating for reaction, and after the reaction is finished, carrying out precipitation separation and vacuum drying on a reaction product to obtain a bromine-novel hard long-chain-bromine compound;
(2) preparing xanthate-novel hard long chain-xanthate compound: adding bromine-novel hard long chain-bromine compound and ethyl xanthate into an acetonitrile solvent, uniformly mixing to obtain a mixed solution, reacting the mixed solution at room temperature in a nitrogen atmosphere, filtering a reaction product after the reaction is finished, distilling the reaction product under reduced pressure, dissolving the reaction product in dichloromethane, filtering, washing by using a saturated sodium chloride aqueous solution, drying, filtering, distilling, precipitating in diethyl ether to obtain a polymer, and drying the polymer at room temperature in vacuum to obtain the xanthate-novel hard long chain-xanthate compound;
(3) preparing a soft segment and hard segment combined compound: dissolving the xanthate-novel hard long chain-xanthate compound in a tetrahydrofuran solvent, adding n-butylamine, reacting at room temperature, and after the reaction is finished, precipitating, filtering and drying a reaction product in vacuum to obtain a soft-segment and hard-segment combined compound;
(4) preparation of the elastomeric polymeric binder: dissolving chitosan in a mixed solution of N, N-dimethylformamide and acetic acid, adding a soft-segment combination compound and a catalyst, stirring and reacting at 4 ℃ for 20-24h, and after the reaction is finished, freeze-drying a reaction product to obtain the elastic polymer binder.
2. The method for preparing an elastic polymer binder for an ion battery silicon electrode according to claim 1, wherein in the step (1), the mass ratio of the novel hard long-chain compound, 2-ethyl-2-oxazoline and acetonitrile is 4-5:8-12: 20-40.
3. The method for preparing an elastic polymer binder applied to an ion battery silicon electrode according to claim 1, wherein in the step (1), the heating reaction temperature is 75-80 ℃ and the heating reaction time is 20-24 h.
4. The method of claim 1, wherein in step (2), the mass ratio of the bromine-novel hard long-chain-bromine complex to ethyl xanthate is 43:29-64, and the ethyl xanthate is sodium ethyl xanthate or potassium ethyl xanthate.
5. The method for preparing an elastic polymer binder applied to a silicon electrode of an ion battery as claimed in claim 1, wherein in the step (2), the reaction time is 15-18h, and the vacuum drying time is 20-28 h.
6. The method for preparing the elastic polymer binder applied to the silicon electrode of the ion battery as claimed in claim 1, wherein in the step (3), the mass ratio of the xanthate-novel hard long chain-xanthate compound to n-butylamine is 4-5:2-4, the reaction time is 4-6h, and the vacuum drying time is 20-28 h.
7. The method for preparing an elastic polymer binder for silicon electrodes of ion batteries according to claim 1, wherein in the step (4), the mass ratio of the chitosan, the soft and hard segment combined compound and the catalyst is 1:1:0.05-0.1, the catalyst is a mixture of 1-ethyl-3- (dimethylaminopropyl carbodiimide) and N-hydroxysuccinimide, and the mass ratio of 1-ethyl-3- (dimethylaminopropyl carbodiimide) and N-hydroxysuccinimide is 4: 1.
8. The method for preparing an elastic polymer binder for an ion battery silicon electrode according to claim 1, wherein in the step (1), the method for preparing the novel hard long-chain composite comprises the following steps: adding 4, 4-bis (3, 5-dibromo-4-hydroxybenzene) valeric acid, a catalyst and diphenylmethane isocyanate into a tetrahydrofuran solvent in a nitrogen atmosphere, stirring for 20-40min at the temperature of 60-80 ℃, and then carrying out vacuum drying to obtain the novel hard long-chain compound.
9. The method for preparing the elastic polymer adhesive applied to the silicon electrode of the ionic cell as claimed in claim 8, wherein the mass ratio of the 4, 4-bis (3, 5-dibromo-4-hydroxyphenyl) pentanoic acid to the catalyst to the diphenylmethane isocyanate is 6-7:0.01-0.03:2-3, and the catalyst is dibutyltin dilaurate or stannous octoate.
10. An elastic polymer binder for use in silicon electrodes of ion batteries obtainable by a process according to any one of claims 1 to 9.
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| CN114824177A (en) * | 2022-03-24 | 2022-07-29 | 合肥国轩高科动力能源有限公司 | Preparation method of silicon negative electrode composite pole piece |
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| CN114824177A (en) * | 2022-03-24 | 2022-07-29 | 合肥国轩高科动力能源有限公司 | Preparation method of silicon negative electrode composite pole piece |
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