Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides the preparation method and the application of the lithium ion battery silicon monoxide composite negative electrode material, which can effectively solve the problem of large volume expansion of the silicon negative electrode and remarkably improve the structural stability and the cycling stability of the silicon negative electrode.
The purpose of the invention is realized by the following technical scheme:
a preparation method of a silicon monoxide composite negative electrode material of a lithium ion battery comprises the following steps:
providing an adhesive, adding the adhesive into dimethylformamide, and uniformly stirring to obtain a first adhesive layer solution;
providing a silicon monoxide raw material, adding the silicon monoxide raw material into the first bonding layer solution, uniformly stirring, and filtering to obtain a silicon monoxide single-layer composite negative electrode material;
providing modified polyurethane, adding the silicon monoxide single-layer composite negative electrode material into the modified polyurethane, uniformly stirring, and filtering to obtain the silicon monoxide composite negative electrode material of the lithium ion battery.
In one embodiment, the binder is polyacrylic acid.
In one embodiment, in the operation of providing the modified polyurethane, isophorone diisocyanate and polyethylene glycol are added into dimethylformamide, stirred uniformly, then a catalyst is added, a first polymerization reaction is carried out to obtain a polymer A, 4' -dicarboxydiphenyl disulfide is added into the polymer A, and a second polymerization reaction is carried out to obtain the modified polyurethane.
In one embodiment, the catalyst is dibutyltin dilaurate.
In one embodiment, the first polymerization is carried out for 12 to 24 hours at a first polymerization temperature of 25 to 35 ℃.
In one embodiment, the second polymerization reaction is carried out in an operation in which the second polymerization time is controlled to be 12 to 24 hours and the second polymerization temperature is controlled to be 25 to 35 ℃.
In one embodiment, the stirring time is controlled to be 5 to 10 hours in the operation of adding the raw material of the silicon monoxide to the first adhesive layer solution and uniformly stirring.
In one embodiment, in the operation of adding the silicon monoxide single-layer composite negative electrode material into the modified polyurethane and uniformly stirring, the stirring time is controlled to be 5-10 h.
In one embodiment, the mass ratio of the isophorone diisocyanate, the 4,4' -dicarboxydiphenyl disulfide and the polyethylene glycol is 1-2: 1-2: 20.
a silicon monoxide composite negative electrode material of a lithium ion battery is prepared by the preparation method of the silicon monoxide composite negative electrode material of the lithium ion battery. The lithium ion battery cathode material has good application prospect in lithium battery cathode materials.
Compared with the prior art, the invention has at least the following advantages:
(1) according to the invention, the silicon oxide raw material is added into the first bonding layer solution, the mixture is stirred uniformly to react, then the first bonding layer is formed on the surface of the silicon oxide raw material, the silicon oxide single-layer composite negative electrode material is obtained, then the modified polyurethane is provided, the silicon oxide single-layer composite negative electrode material is added into the modified polyurethane, the mixture is stirred uniformly, and the modified polyurethane layer, namely the second bonding layer, is formed on the surface of the silicon oxide single-layer composite negative electrode material, so that a double-layer structure is formed on the surface of the silicon oxide material, the lithium ion battery silicon oxide composite negative electrode material is obtained, the gradual dissipation of the stress of the lithium ion battery silicon oxide composite negative electrode material can be realized, the quick self-repairing function is realized, the problem of large volume expansion of the silicon negative electrode material can be effectively solved, and the cycle stability of.
(2) The lithium ion battery silicon monoxide composite negative electrode material provided by the invention has a double-layer structure, internal stress generated in a lithium embedding process can be eliminated, and the modified polyurethane can be used as a buffer layer to disperse residual stress, so that the first bonding layer is prevented from being damaged. In addition, modified polyurethane with a quick self-repairing function is introduced to form a modified polyurethane layer, and microcracks generated by large stress can be dynamically recovered, so that the integrity and structural stability of the silicon oxide composite negative electrode material of the lithium ion battery are further ensured.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
In one embodiment, referring to fig. 1, a method for preparing a negative silicon oxide composite material for a lithium ion battery includes the following steps:
s110, providing an adhesive, adding the adhesive into dimethylformamide, and uniformly stirring to obtain a first adhesive layer solution.
The adhesive is added into the dimethylformamide and uniformly stirred, so that a first adhesive layer solution is prepared, the subsequent silicon monoxide raw material is conveniently and better dispersed in the first adhesive layer solution, the first adhesive layer is favorably formed on the surface of the silicon monoxide raw material, and the quality of the prepared silicon monoxide composite negative electrode material of the lithium ion battery is favorably improved. In particular, the binder is polyacrylic acid. Polyacrylic acid is used as a raw material of the first bonding layer, the polyacrylic acid is a rigid bonding agent and has high Young modulus, the rigid polyacrylic acid can serve as a protective layer of the silicon protoxide material, internal stress generated in a lithium embedding process can be eliminated, and the silicon protoxide material can be well protected, so that structural stability and integrity of the prepared silicon protoxide composite negative electrode material of the lithium ion battery are ensured.
S120, providing a silicon monoxide raw material, adding the silicon monoxide raw material into the first bonding layer solution, uniformly stirring, and filtering to obtain the silicon monoxide single-layer composite negative electrode material.
The first binding agent layer is formed on the surface of the silica raw material, that is, the polyacrylic acid binding agent layer is formed, and can be used as a protective layer of the silica material, so that the structural stability and integrity of the prepared silica composite negative electrode material of the lithium ion battery are ensured.
In one embodiment, in the operation of adding the raw material of the silica to the solution of the first adhesive layer and uniformly stirring, the stirring time is controlled to be 5 to 10 hours. It should be noted that, when the raw material of the silicon monoxide reacts in the solution of the first adhesive layer to form the first adhesive layer, the integrity of the first adhesive layer and the layer formation needs to be ensured, the formation of the first adhesive layer with a complete structure is favorably ensured by increasing the reaction time, when the stirring time is less than 5 hours, the reaction time is too short, the structural integrity of the formed first adhesive layer cannot be ensured, the quality of the subsequently prepared silicon monoxide composite negative electrode material of the lithium ion battery is easily influenced, when the stirring time is more than 10 hours, the reaction time is too long, the time cost is greatly increased, and the production benefit is not favorably improved, so that the stirring time is controlled to be 5 hours to 10 hours, and thus, the first adhesive layer with a complete structure and moderate thickness, namely the polyacrylic acid adhesive layer, can be formed on the surface of the raw material of the silicon monoxide.
S130, providing modified polyurethane, adding the silicon monoxide single-layer composite negative electrode material into the modified polyurethane, uniformly stirring, and filtering to obtain the silicon monoxide composite negative electrode material of the lithium ion battery.
It is to be noted that, the monox composite negative electrode material is added into the modified polyurethane, and is uniformly stirred and reacts to form a second adhesive layer on the surface of the monox composite negative electrode material, that is, a modified polyurethane adhesive layer is formed, the modified polyurethane is a flexible adhesive, has a low young modulus, and serves as an outer layer structure, and can serve as a buffer layer to disperse residual stress, so as to avoid the rigid polyacrylic acid layer from being damaged, therefore, the inner layer of the prepared monox composite negative electrode material for the lithium ion battery is polyacrylic acid with a high young modulus, that is, a rigid inner layer structure, and the outer layer is the modified polyurethane with a low young modulus, so that the monox composite negative electrode material for the lithium ion battery has a structure with gradient distribution from hard to soft, and the rigid polyacrylic acid serves as a protective layer, and can eliminate internal stress generated in the lithium embedding process of the monox composite negative electrode material for the lithium ion battery, the modified polyurethane can disperse residual stress as a buffer layer, so that a rigid polyacrylic acid layer is prevented from being damaged, meanwhile, the introduced modified polyurethane has a quick self-repairing function, and microcracks generated under high stress can be dynamically recovered, so that the structural stability and integrity of the silicon oxide composite negative electrode material of the lithium ion battery are further ensured, the problem of large-volume expansion of the silicon negative electrode material can be effectively solved, and the cycle stability of the silicon negative electrode material is remarkably improved.
In one embodiment, in the operation of providing the modified polyurethane, isophorone diisocyanate and polyethylene glycol are added into dimethylformamide, stirred uniformly, then a catalyst is added, a first polymerization reaction is carried out to obtain a polymer A, and 4,4' -dicarboxydiphenyl disulfide is added into the polymer A, a second polymerization reaction is carried out to obtain the modified polyurethane. It is understood that isophorone diisocyanate is abbreviated as IPDI and has the formula C12H18N2O2The polymer A is prepared by reacting alicyclic diisocyanate with polyethylene glycol under the action of a catalyst, and specifically, the catalyst is dibutyltin dilaurate. That is, a polyurethane catalyst dibutyltin dilaurate is adopted, the specific reaction is that isophorone diisocyanate and polyethylene glycol are dissolved in dimethylformamide, a catalyst dibutyltin dilaurate is added, a first polymerization reaction is carried out, a polymer A is obtained after the reaction for a period of time, and the chemical structural formula of the polymer A is as follows:
then adding 4,4' -dicarboxydiphenyl disulfide, carrying out secondary polymerization reaction for a period of time to obtain the modified polyurethane, wherein the chemical structural formula of the modified polyurethane is as follows:
wherein n1 is more than or equal to 45 and less than or equal to 110, and n2 is more than or equal to 10 and less than or equal to 30. The prepared modified polyurethane is a flexible adhesive, has low Young modulus, can serve as a buffer layer to disperse residual stress, so that a rigid polyacrylic acid layer is prevented from being damaged, and meanwhile, the modified polyurethane has a quick self-repairing function and can dynamically recover microcracks generated under large stress, so that the structural stability and integrity of the silicon oxide composite negative electrode material of the lithium ion battery are further ensured, the problem of large-volume expansion of the silicon negative electrode material can be effectively solved, and the cycle stability of the silicon negative electrode material is remarkably improved.
In one embodiment, in the operation of carrying out the first polymerization reaction, the first polymerization time is controlled to be 12 to 24 hours, and the first polymerization temperature is controlled to be 25 to 35 ℃. In the operation of carrying out the secondary polymerization reaction, the secondary polymerization time is controlled to be 12-24 h, and the secondary polymerization temperature is controlled to be 25-35 ℃. Thus, the full progress of the polymerization reaction is ensured, and the modified polyurethane with good quality is prepared.
In one embodiment, the mass ratio of the isophorone diisocyanate to the 4,4' -dicarboxydiphenyl disulfide to the polyethylene glycol is 1-2: 1-2: 20. it can be understood that the mass ratio of isophorone diisocyanate, 4' -dicarboxydiphenyl disulfide and polyethylene glycol is strictly limited, so that the polymerization reaction of the substances according to a certain proportion can be ensured, the preparation of modified polyurethane with excellent performance can be ensured, and the subsequent preparation of the high-quality silicon oxide composite negative electrode material for the lithium ion battery can be facilitated.
In one embodiment, in the operation of adding the silicon monoxide single-layer composite negative electrode material into the modified polyurethane and uniformly stirring, the stirring time is controlled to be 5-10 h. When the single-layer composite negative electrode material of silicon oxide is reacted in the modified polyurethane to form the second binder layer, the integrity of the second adhesive and the layer formation needs to be ensured, and the formation of the second adhesive layer with complete structure is facilitated by increasing the reaction time, when the stirring time is less than 5 hours, the reaction time is too short, the structural integrity of the formed second adhesive layer cannot be ensured, the quality of the subsequently prepared silicon oxide composite negative electrode material of the lithium ion battery is easily influenced, when the stirring time is longer than 10 hours, the reaction time is too long, the time cost is greatly increased, and the production benefit is not favorably improved, so that the stirring time is preferably controlled to be 5 to 10 hours, and thus, the second adhesive layer with complete structure and moderate thickness, namely the modified polyurethane adhesive layer, can be formed on the surface of the monofilm composite negative electrode material of the monofilm silicon oxide.
A silicon monoxide composite negative electrode material of a lithium ion battery is prepared by the preparation method of the silicon monoxide composite negative electrode material of the lithium ion battery. The lithium ion battery cathode material has good application prospect in lithium battery cathode materials.
Compared with the prior art, the invention has at least the following advantages:
(1) according to the invention, the silicon oxide raw material is added into the first bonding layer solution, the mixture is stirred uniformly to react, then the first bonding layer is formed on the surface of the silicon oxide raw material, the silicon oxide single-layer composite negative electrode material is obtained, then the modified polyurethane is provided, the silicon oxide single-layer composite negative electrode material is added into the modified polyurethane, the mixture is stirred uniformly, and the modified polyurethane layer, namely the second bonding layer, is formed on the surface of the silicon oxide single-layer composite negative electrode material, so that a double-layer structure is formed on the surface of the silicon oxide material, the lithium ion battery silicon oxide composite negative electrode material is obtained, the gradual dissipation of the stress of the lithium ion battery silicon oxide composite negative electrode material can be realized, the quick self-repairing function is realized, the problem of large volume expansion of the silicon negative electrode material can be effectively solved, and the cycle stability of.
(2) The lithium ion battery silicon monoxide composite negative electrode material provided by the invention has a double-layer structure, internal stress generated in a lithium embedding process can be eliminated, and the modified polyurethane can be used as a buffer layer to disperse residual stress, so that the first bonding layer is prevented from being damaged. In addition, modified polyurethane with a quick self-repairing function is introduced to form a modified polyurethane layer, and microcracks generated by large stress can be dynamically recovered, so that the integrity and structural stability of the silicon oxide composite negative electrode material of the lithium ion battery are further ensured.
The following is a detailed description of the embodiments.
Example 1
Providing polyacrylic acid, adding the polyacrylic acid into dimethylformamide, and uniformly stirring to obtain a first bonding layer solution;
providing a silicon monoxide raw material, adding the silicon monoxide raw material into the first bonding layer solution, uniformly stirring, controlling the stirring time to be 5h, and then filtering to obtain a silicon monoxide single-layer composite negative electrode material;
adding isophorone diisocyanate and polyethylene glycol into dimethylformamide, stirring uniformly, adding dibutyltin dilaurate, carrying out primary polymerization reaction, controlling the primary polymerization time to be 12h and the primary polymerization temperature to be 25 ℃ to obtain a polymer A, adding 4,4 '-dicarboxydiphenyl disulfide into the polymer A, carrying out secondary polymerization reaction, controlling the secondary polymerization time to be 12h and the secondary polymerization temperature to be 25 ℃ to obtain the modified polyurethane, wherein the mass ratio of isophorone diisocyanate to 4,4' -dicarboxydiphenyl disulfide to polyethylene glycol is 1: 1: and 20, adding the silicon monoxide single-layer composite negative electrode material into the modified polyurethane, uniformly stirring, controlling the stirring time to be 5 hours, and then filtering to obtain the silicon monoxide composite negative electrode material of the lithium ion battery in the embodiment 1.
Example 2
Providing polyacrylic acid, adding the polyacrylic acid into dimethylformamide, and uniformly stirring to obtain a first bonding layer solution;
providing a silicon monoxide raw material, adding the silicon monoxide raw material into the first bonding layer solution, uniformly stirring, controlling the stirring time to be 8h, and then filtering to obtain a silicon monoxide single-layer composite negative electrode material;
adding isophorone diisocyanate and polyethylene glycol into dimethylformamide, stirring uniformly, adding dibutyltin dilaurate, carrying out primary polymerization reaction, controlling the primary polymerization time to be 20h and the primary polymerization temperature to be 30 ℃ to obtain a polymer A, adding 4,4 '-dicarboxydiphenyl disulfide into the polymer A, carrying out secondary polymerization reaction, controlling the secondary polymerization time to be 20h and the secondary polymerization temperature to be 30 ℃ to obtain the modified polyurethane, wherein the mass ratio of isophorone diisocyanate to 4,4' -dicarboxydiphenyl disulfide to polyethylene glycol is 1.5: 1.5: and 20, adding the silicon monoxide single-layer composite negative electrode material into the modified polyurethane, uniformly stirring, controlling the stirring time to be 8 hours, and then filtering to obtain the silicon monoxide composite negative electrode material of the lithium ion battery in the embodiment 2.
Example 3
Providing polyacrylic acid, adding the polyacrylic acid into dimethylformamide, and uniformly stirring to obtain a first bonding layer solution;
providing a silicon monoxide raw material, adding the silicon monoxide raw material into the first bonding layer solution, uniformly stirring, controlling the stirring time to be 10h, and then filtering to obtain a silicon monoxide single-layer composite negative electrode material;
adding isophorone diisocyanate and polyethylene glycol into dimethylformamide, stirring uniformly, adding dibutyltin dilaurate, carrying out a first polymerization reaction, controlling the first polymerization time to be 24 hours and the first polymerization temperature to be 35 ℃ to obtain a polymer A, adding 4,4 '-dicarboxydiphenyl disulfide into the polymer A, carrying out a second polymerization reaction, controlling the second polymerization time to be 24 hours and the second polymerization temperature to be 35 ℃ to obtain the modified polyurethane, wherein the mass ratio of isophorone diisocyanate to 4,4' -dicarboxydiphenyl disulfide to polyethylene glycol is 2: 2: and 20, adding the silicon monoxide single-layer composite negative electrode material into the modified polyurethane, uniformly stirring, controlling the stirring time to be 10 hours, and then filtering to obtain the silicon monoxide composite negative electrode material of the lithium ion battery in the embodiment 3.
Example 4
Providing polyacrylic acid, adding the polyacrylic acid into dimethylformamide, and uniformly stirring to obtain a first bonding layer solution;
providing a silicon monoxide raw material, adding the silicon monoxide raw material into the first bonding layer solution, uniformly stirring, controlling the stirring time to be 8.5h, and then filtering to obtain a silicon monoxide single-layer composite negative electrode material;
adding isophorone diisocyanate and polyethylene glycol into dimethylformamide, stirring uniformly, adding dibutyltin dilaurate, carrying out a first polymerization reaction, controlling the first polymerization time to be 20.5h and the first polymerization temperature to be 32 ℃ to obtain a polymer A, adding 4,4 '-dicarboxydiphenyl disulfide into the polymer A, carrying out a second polymerization reaction, controlling the second polymerization time to be 20.5h and the second polymerization temperature to be 32 ℃, and obtaining the modified polyurethane, wherein the mass ratio of isophorone diisocyanate to 4,4' -dicarboxydiphenyl disulfide to polyethylene glycol is 1.2: 1.8: and 20, adding the silicon monoxide single-layer composite negative electrode material into the modified polyurethane, uniformly stirring, controlling the stirring time to be 8.5h, and then filtering to obtain the silicon monoxide composite negative electrode material of the lithium ion battery in the embodiment 4.
Comparative example 1
Providing polyacrylic acid, adding the polyacrylic acid into dimethylformamide, and uniformly stirring to obtain a first bonding layer solution;
providing a silicon monoxide raw material, adding the silicon monoxide raw material into the first bonding layer solution, uniformly stirring, controlling the stirring time to be 8.5h, and then filtering to obtain the silicon monoxide single-layer composite negative electrode material of the lithium ion battery of the comparative example 1;
comparative example 2
Providing polyacrylic acid, adding the polyacrylic acid into dimethylformamide, and uniformly stirring to obtain a first bonding layer solution;
providing a silicon monoxide raw material, adding the silicon monoxide raw material into the first bonding layer solution, uniformly stirring, controlling the stirring time to be 8.5h, and then filtering to obtain a silicon monoxide single-layer composite negative electrode material;
and adding the monofilm composite negative electrode material of the silicon oxide into the polyurethane adhesive with the CAS number of CAS 51852-81-4 by adopting the polyurethane adhesive with the CAS number of CAS 51852-81-4, uniformly stirring, controlling the stirring time to be 8.5h, and filtering to obtain the monofilm composite negative electrode material of the lithium ion battery of the comparative example 2.
Experiment: the lithium ion battery silicon oxide composite negative electrode materials obtained in the embodiments 1 to 4 and the comparative examples 1 and 2 are used for preparing electrodes and assembling to obtain the lithium ion battery,
and (3) testing: in the above examples, the lithium ion batteries of examples 1, 2, 3 and 4 and comparative examples 1 and 2 were subjected to various tests, and the test results are shown in table 1 and fig. 2.
TABLE 1
As can be seen from the above table, compared with the lithium ion batteries of comparative example 1 and comparative example 2, the lithium ion batteries prepared in examples 1 to 4 all have excellent cycle life, the structure of the lithium ion battery is more stable, the service life is longer, the quality of the lithium ion batteries prepared in examples 1 to 4 is higher than that of comparative example 1 and comparative example 2, the preparation processes of the above embodiments are simple, the assembled lithium ion batteries show good cycle stability, and the cycle life of the lithium ion batteries is prolonged.
And (4) at normal temperature, carrying out 2C rate charging, 1C rate discharging and lithium ion battery discharging cycle performance testing. The test results show that the lithium ion batteries of the embodiments of the invention have excellent charging and discharging performance at different multiplying factors compared with the comparative examples 1 and 2, and are shown in detail in fig. 2, wherein, in order to avoid the data in the figure being too dense and difficult to distinguish, fig. 2 only takes the data of the embodiment 4 and makes a chart with the data of the comparative examples 1 and 2, and the results are shown in fig. 2. The effects of the other embodiments are similar to those of embodiment 3, and are not described again.
Specifically, fig. 2 is a comparative graph of discharge cycle performance tests of the lithium ion batteries of example 4, comparative example 1 and comparative example 2 according to the present invention. Wherein, 1 represents the lithium ion battery of example 4; 2 represents the lithium ion battery of comparative example 2; and 3 represents the lithium ion battery of comparative example 1. As can be seen from fig. 2, at room temperature, the capacity of the lithium ion battery of example 4 hardly faded and the capacity retention ratio was high, with charge at 2C rate and discharge at 1C rate, and cycling for 240 weeks. That is, the cycle performance of the lithium ion batteries of examples 1 to 4 is better than that of comparative example 1 and comparative example 2, and the results prove that the silicon oxide composite negative electrode material of the lithium ion battery prepared by the method of the invention has stable structure, good performance, long service life, excellent structural stability and cycle stability, and obviously improved cycle performance.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.