CN117650275A - Lithium iron manganese phosphate battery adaptive electrolyte and preparation method and application thereof - Google Patents

Lithium iron manganese phosphate battery adaptive electrolyte and preparation method and application thereof Download PDF

Info

Publication number
CN117650275A
CN117650275A CN202311812307.7A CN202311812307A CN117650275A CN 117650275 A CN117650275 A CN 117650275A CN 202311812307 A CN202311812307 A CN 202311812307A CN 117650275 A CN117650275 A CN 117650275A
Authority
CN
China
Prior art keywords
electrolyte
additive
lithium
lithium salt
mass ratio
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202311812307.7A
Other languages
Chinese (zh)
Inventor
邵俊华
童登辉
王亚洲
韩飞
宋东亮
李渠成
张利娟
李海杰
施艳霞
司雅楠
郭飞
闫志卫
王郝为
闫国锋
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Anhui Fanlaite New Energy Technology Co ltd
Henan Faenlaite New Energy Technology Co ltd
Hunan Farnlet New Energy Technology Co ltd
Original Assignee
Anhui Fanlaite New Energy Technology Co ltd
Henan Faenlaite New Energy Technology Co ltd
Hunan Farnlet New Energy Technology Co ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Anhui Fanlaite New Energy Technology Co ltd, Henan Faenlaite New Energy Technology Co ltd, Hunan Farnlet New Energy Technology Co ltd filed Critical Anhui Fanlaite New Energy Technology Co ltd
Priority to CN202311812307.7A priority Critical patent/CN117650275A/en
Publication of CN117650275A publication Critical patent/CN117650275A/en
Pending legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/056Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566Liquid materials
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/052Li-accumulators
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/056Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566Liquid materials
    • H01M10/0567Liquid materials characterised by the additives

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Inorganic Chemistry (AREA)
  • Secondary Cells (AREA)

Abstract

The invention discloses a manganese iron phosphate lithium battery adaptive electrolyte, and a preparation method and application thereof. Relates to the technical field of secondary battery electrolyte. The electrolyte comprises the following components: a lithium salt; an organic solvent; an additive; the additive comprises at least one of vanadium oxide, heptamethyldisilazane, diphenyldiethoxysilane, N-dimethylformamide, and at least vanadium oxide and diphenyldiethoxysilane. The electrolyte provided by the invention can solve the problem that the cycle performance is rapidly deteriorated due to the massive dissolution of transition metal Mn. The invention improves the battery dynamics and the multiplying power performance through the cooperative use of the additives.

Description

Lithium iron manganese phosphate battery adaptive electrolyte and preparation method and application thereof
Technical Field
The invention relates to the technical field of secondary battery electrolyte, in particular to a manganese iron phosphate lithium battery adaptive electrolyte, a preparation method and application thereof.
Background
The current widely used positive electrode material mainly comprises three systems of lamellar, spinel and olivine, and the lamellar positive electrode material comprises lithium cobaltate and ternary materials. The spinel positive electrode material is lithium manganate, the olive Dan Zheng positive electrode material is lithium iron phosphate, the lithium cobaltate and the lithium manganate are mainly applied to the field of consumer electronics, and the lithium iron phosphate and the ternary material are applied to the field of electric vehicles. This is because lithium iron phosphate has advantages of good structural stability, low cost, long cycle life, and the like.
However, lithium iron manganese phosphate materials have been deficient and have mainly the following problems: (1) The charge-discharge rate characteristics are affected by the lower electron conductivity and ion diffusion coefficient; (2) The difference of the charging and discharging voltages of manganese and iron causes the dual-voltage platform to appear in the LMFP, and the management difficulty of the later BMS is increased. Taking discharge process as an example, mn 2+ Conversion to Mn around 4.1V 3+ ,Fe 2+ Conversion to Fe around 3.5V 3+ This results in a dual voltage platform for LMFP, which causes a problem of voltage dip during discharge, thereby increasing management difficulty of a later Battery Management System (BMS); (3) Poor cycle performance, the Mn ions of the positive electrode are separated out mainly due to the ginger-Taylor (Jahn-Teller) effect, so that lattice distortion and structural stability are reduced, and stability and cyclicity are affected; (4) Manganese dissolved in the electrolyte can be deposited on the surface of the negative electrode to destroy the SEI layer structure, so that micro short circuit is caused, self-discharge of the battery core is increased, and the cyclicity is reduced; (5) The smaller particles of material result in a lower compacted density, which in turn affects the energy density performance of the overall material.
The problem at point (4) not only affects the battery cycle but also causes a short circuit. Based on this, it is necessary to solve the problem of elution of the transition metal Mn stated in the above (4), which is important for improving the performance and safety of the lithium iron manganese phosphate battery.
Disclosure of Invention
The first technical problem to be solved by the invention is as follows:
an electrolyte is provided.
The second technical problem to be solved by the invention is as follows:
a method for preparing the electrolyte is provided.
The third technical problem to be solved by the invention is:
the application of the electrolyte.
The invention also provides a lithium iron manganese phosphate battery, which comprises the electrolyte.
In order to solve the first technical problem, the invention adopts the following technical scheme:
an electrolyte comprising the following components:
a lithium salt;
an organic solvent;
an additive;
the additive comprises at least one of vanadium oxide, heptamethyldisilazane, diphenyldiethoxysilane, N-dimethylformamide, and at least vanadium oxide and diphenyldiethoxysilane.
According to the embodiments of the present invention, one of the technical solutions has at least one of the following advantages or beneficial effects:
the invention provides an electrolyte which can be adapted to a lithium iron manganese phosphate battery. The electrolyte provided by the invention can solve the problem that the cycle performance is rapidly deteriorated due to the massive dissolution of transition metal Mn. The invention improves the battery dynamics and the multiplying power performance through the cooperative use of the additives.
Wherein, the additive heptamethyldisilazane (7-HMDS) can react with HF to form a salt compound to participate in the formation of SEI film, thereby reducing the content of HF in the electrolyte and inhibiting the dissolution of transition metal Mn, and improving the cycle performance of the battery; wherein, the additive diphenyl diethoxy silane (DPDS) can carry out preferential electrochemical oxidation polymerization on the anode and the cathode, and the decomposition products are doped in SEl and CEl, which is helpful for forming an interfacial film with good protectiveness and ion conductivity on the two electrodes, and can obviously inhibit the decomposition of electrolyte and the deposition of Mn ions at high temperature; wherein the additive N, N Dimethylformamide (DMF) can capture LiPF 6 Is the decomposition product PF of (2) 5 . DMF self lone electron pair and PF in electrolyte 5 The electronic structure combination of the electrolyte further prevents the side reaction of the electrolyte and the corrosion of electrode materials, and has important significance for promoting the large-scale application of the lithium ion battery at high temperature.
According to one embodiment of the invention, the additive accounts for 1-5% of the total mass of the electrolyte.
According to one embodiment of the invention, the additive comprises heptamethyldisilazane, diphenyl-bisThe mass ratio of the heptamethyldisilazane, the diphenyl diethoxysilane and the N, N-dimethylformamide to the total mass of the electrolyte is 1.5-2%. The addition of an excess of heptamethyldisilazane (7-HMDS) may result in the addition of a nitrogen nucleus of a lone pair of electrons in heptamethyldisilazane to the Lewis acid PF 5 Formation of weak complexes, avoiding PF 5 And the presence of the solvent, thereby improving the stability of the electrolyte. In addition, when the addition amounts of the three additives (heptamethyldisilazane, diphenyldiethoxysilane, and N, N dimethylformamide) in the electrolyte are all 1.5% -2% (preferably 2%), the battery including the electrolyte has the best cycle performance at 25 ℃ and 45 ℃ and can still maintain an extremely high capacity retention rate when stored at 60 ℃ for 35 days; and the DCR of the battery at normal temperature and low temperature can be the lowest, which shows that the multiplying power performance of the battery is also excellent.
According to one embodiment of the invention, the diphenyl diethoxysilane accounts for 0.5% -2% of the total mass of the electrolyte. When the mass ratio of the diphenyl diethoxy silane in the electrolyte to the total mass of the electrolyte is 0.5-2%, the cycle performance of the battery comprising the electrolyte at high and low temperatures is improved along with the improvement of the mass ratio of the diphenyl diethoxy silane.
According to one embodiment of the invention, the diphenyl diethoxysilane accounts for 0.5% -0.6% of the total mass of the electrolyte. When the mass ratio of the diphenyl diethoxy silane in the electrolyte to the total mass of the electrolyte is 0.5-0.6%, the battery comprising the electrolyte has the best cycle performance at high and low temperatures.
According to one embodiment of the present invention, the lithium salt includes at least one of lithium hexafluorophosphate, lithium bis-fluoromethylsulfonimide, lithium difluorooxalato borate, and lithium difluorophosphate.
According to one embodiment of the present invention, the organic solvent includes at least one of ethylene carbonate, propylene carbonate, ethylmethyl carbonate, dimethyl carbonate, and diethyl carbonate.
According to one embodiment of the invention, the mass ratio of the lithium salt to the organic solvent is 10-20:60-85.
In order to solve the second technical problem, the invention adopts the following technical scheme:
a method of preparing the electrolyte comprising the steps of:
mixing lithium salt and additive in organic solvent to obtain the electrolyte.
According to one embodiment of the invention, the method for preparing the electrolyte comprises the following steps: firstly, preparing lithium salt, a solvent and an additive in advance according to a preset mass ratio; secondly, adding lithium salt and an additive into a solvent, and mixing together; and thirdly, uniformly stirring by a stirrer to obtain the electrolyte.
In another aspect of the invention, a lithium iron manganese phosphate battery is also provided. Comprising an electrolyte as described in the embodiment of aspect 1 above. The application adopts all the technical schemes of the electrolyte, so that the electrolyte has at least all the beneficial effects brought by the technical schemes of the embodiment.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Detailed Description
The words "preferably," "more preferably," and the like in the present invention refer to embodiments of the invention that may provide certain benefits in some instances. However, other embodiments may be preferred under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the invention.
When a range of values is disclosed herein, the range is considered to be continuous and includes both the minimum and maximum values for the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values of the range is included. Further, when multiple range description features or characteristics are provided, the ranges may be combined. In other words, unless otherwise indicated, all ranges disclosed herein are to be understood to include any and all subranges subsumed therein.
The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to fall within the scope of the invention.
The reagents, methods and apparatus employed in the present invention, unless otherwise specified, are all conventional in the art.
Example 1
An electrolyte comprising the following components:
a lithium salt;
an organic solvent;
an additive.
Wherein the lithium salt comprises the following components in mass ratio, and the mass ratio is the ratio of the lithium salt to the electrolyte:
lithium hexafluorophosphate (LiPF) 6 ),13%;
Lithium difluorooxalato borate (LiDFOB), 0.5%;
wherein the organic solvent comprises the following components in percentage by mass:
ethylene Carbonate (EC), 35%;
methyl ethyl carbonate (EMC), 39%;
diethyl carbonate (DEC), 10%;
wherein the additive comprises the following components in percentage by mass:
heptamethyldisilazane (7-HMDS), 0.5%;
diphenyldiethoxysilane (DPDS), 0.5%;
n, N Dimethylformamide (DMF), 0.5%;
and a negative film forming additive VC (vanadium oxide) accounting for 1 percent.
The preparation method of the electrolyte comprises the following steps:
firstly, preparing lithium salt, a solvent and an additive in advance according to a preset mass ratio;
a second step of adding a lithium salt and an additive to the solvent;
and thirdly, uniformly stirring by a stirrer to obtain the electrolyte.
Example 2
An electrolyte comprising the following components:
a lithium salt;
an organic solvent;
an additive.
Wherein the lithium salt comprises the following components in mass ratio, and the mass ratio is the ratio of the lithium salt to the electrolyte:
lithium hexafluorophosphate (LiPF) 6 ),13%;
Lithium difluorooxalato borate (LiDFOB), 0.5%;
wherein the organic solvent comprises the following components in percentage by mass:
ethylene Carbonate (EC), 34.5%;
ethyl Methyl Carbonate (EMC), 38.5%;
diethyl carbonate (DEC), 9.5%;
wherein the additive comprises the following components in percentage by mass:
heptamethyldisilazane (7-HMDS), 1%;
diphenyldiethoxysilane (DPDS), 1%;
n, N Dimethylformamide (DMF), 1%;
and a negative film forming additive VC (vanadium oxide) accounting for 1 percent.
The preparation method of the electrolyte comprises the following steps:
firstly, preparing lithium salt, a solvent and an additive in advance according to a preset mass ratio;
a second step of adding a lithium salt and an additive to the solvent;
and thirdly, uniformly stirring by a stirrer to obtain the electrolyte.
Example 3
An electrolyte comprising the following components:
a lithium salt;
an organic solvent;
an additive.
Wherein the lithium salt comprises the following components in mass ratio, and the mass ratio is the ratio of the lithium salt to the electrolyte:
lithium hexafluorophosphate (LiPF) 6 ),13%;
Lithium difluorooxalato borate (LiDFOB), 0.5%;
wherein the organic solvent comprises the following components in percentage by mass:
ethylene Carbonate (EC), 34%;
methyl ethyl carbonate (EMC), 38%;
diethyl carbonate (DEC), 9%;
wherein the additive comprises the following components in percentage by mass:
heptamethyldisilazane (7-HMDS), 1.5%;
diphenyl diethoxysilane (DPDS), 1.5%;
n, N Dimethylformamide (DMF), 1.5%;
and a negative film forming additive VC (vanadium oxide) accounting for 1 percent.
The preparation method of the electrolyte comprises the following steps:
firstly, preparing lithium salt, a solvent and an additive in advance according to a preset mass ratio;
a second step of adding a lithium salt and an additive to the solvent;
and thirdly, uniformly stirring by a stirrer to obtain the electrolyte.
Example 4
An electrolyte comprising the following components:
a lithium salt;
an organic solvent;
an additive.
Wherein the lithium salt comprises the following components in mass ratio, and the mass ratio is the ratio of the lithium salt to the electrolyte:
lithium hexafluorophosphate (LiPF) 6 ),13%;
Lithium difluorooxalato borate (LiDFOB), 0.5%;
wherein the organic solvent comprises the following components in percentage by mass:
ethylene Carbonate (EC), 33.5%;
methyl ethyl carbonate (EMC), 37.5%;
diethyl carbonate (DEC), 8.5%;
wherein the additive comprises the following components in percentage by mass:
heptamethyldisilazane (7-HMDS), 2%;
diphenyldiethoxysilane (DPDS), 2%;
n, N Dimethylformamide (DMF), 2%;
and 2% of a negative film forming additive VC (vanadium oxide).
The preparation method of the electrolyte comprises the following steps:
firstly, preparing lithium salt, a solvent and an additive in advance according to a preset mass ratio;
a second step of adding a lithium salt and an additive to the solvent;
and thirdly, uniformly stirring by a stirrer to obtain the electrolyte.
Example 5
An electrolyte comprising the following components:
a lithium salt;
an organic solvent;
an additive.
Wherein the lithium salt comprises the following components in mass ratio, and the mass ratio is the ratio of the lithium salt to the electrolyte:
lithium hexafluorophosphate (LiPF) 6 ),13%;
Lithium difluorooxalato borate (LiDFOB), 0.5%;
wherein the organic solvent comprises the following components in percentage by mass:
ethylene Carbonate (EC), 33.5%;
methyl ethyl carbonate (EMC), 37.5%;
diethyl carbonate (DEC), 8.5%;
wherein the additive comprises the following components in percentage by mass:
diphenyldiethoxysilane (DPDS), 0.5%;
and a negative film forming additive VC (vanadium oxide) accounting for 1 percent.
The preparation method of the electrolyte comprises the following steps:
firstly, preparing lithium salt, a solvent and an additive in advance according to a preset mass ratio;
a second step of adding a lithium salt and an additive to the solvent;
and thirdly, uniformly stirring by a stirrer to obtain the electrolyte.
Example 6
An electrolyte comprising the following components:
a lithium salt;
an organic solvent;
an additive.
Wherein the lithium salt comprises the following components in mass ratio, and the mass ratio is the ratio of the lithium salt to the electrolyte:
lithium hexafluorophosphate (LiPF) 6 ),13%;
Lithium difluorooxalato borate (LiDFOB), 0.5%;
wherein the organic solvent comprises the following components in percentage by mass:
ethylene Carbonate (EC), 33.5%;
methyl ethyl carbonate (EMC), 37.5%;
diethyl carbonate (DEC), 8.5%;
wherein the additive comprises the following components in percentage by mass:
diphenyldiethoxysilane (DPDS), 1%;
and a negative film forming additive VC (vanadium oxide) accounting for 1 percent.
The preparation method of the electrolyte comprises the following steps:
firstly, preparing lithium salt, a solvent and an additive in advance according to a preset mass ratio;
a second step of adding a lithium salt and an additive to the solvent;
and thirdly, uniformly stirring by a stirrer to obtain the electrolyte.
Example 7
An electrolyte comprising the following components:
a lithium salt;
an organic solvent;
an additive.
Wherein the lithium salt comprises the following components in mass ratio, and the mass ratio is the ratio of the lithium salt to the electrolyte:
lithium hexafluorophosphate (LiPF) 6 ),13%;
Lithium difluorooxalato borate (LiDFOB), 0.5%;
wherein the organic solvent comprises the following components in percentage by mass:
ethylene Carbonate (EC), 33.5%;
methyl ethyl carbonate (EMC), 37.5%;
diethyl carbonate (DEC), 8.5%;
wherein the additive comprises the following components in percentage by mass:
diphenyldiethoxysilane (DPDS), 2%;
and a negative film forming additive VC (vanadium oxide) accounting for 1 percent.
The preparation method of the electrolyte comprises the following steps:
firstly, preparing lithium salt, a solvent and an additive in advance according to a preset mass ratio;
a second step of adding a lithium salt and an additive to the solvent;
and thirdly, uniformly stirring by a stirrer to obtain the electrolyte.
Example 8
An electrolyte comprising the following components:
a lithium salt;
an organic solvent;
an additive.
Wherein the lithium salt comprises the following components in mass ratio, and the mass ratio is the ratio of the lithium salt to the electrolyte:
lithium bis (fluoromethylsulfonyl imide), 13%;
lithium difluorophosphate, 0.5%;
wherein the organic solvent comprises the following components in percentage by mass:
ethylene Carbonate (EC), 35%;
methyl ethyl carbonate (EMC), 39%;
diethyl carbonate (DEC), 10%;
wherein the additive comprises the following components in percentage by mass:
heptamethyldisilazane (7-HMDS), 0.5%;
diphenyldiethoxysilane (DPDS), 0.5%;
n, N Dimethylformamide (DMF), 0.5%;
and a negative film forming additive VC (vanadium oxide) accounting for 1 percent.
The preparation method of the electrolyte comprises the following steps:
firstly, preparing lithium salt, a solvent and an additive in advance according to a preset mass ratio;
a second step of adding a lithium salt and an additive to the solvent;
and thirdly, uniformly stirring by a stirrer to obtain the electrolyte.
Example 9
An electrolyte comprising the following components:
a lithium salt;
an organic solvent;
an additive.
Wherein the lithium salt comprises the following components in mass ratio, and the mass ratio is the ratio of the lithium salt to the electrolyte:
lithium hexafluorophosphate (LiPF) 6 ),13%;
Lithium difluorooxalato borate (LiDFOB), 0.5%;
wherein the organic solvent comprises the following components in percentage by mass:
propylene carbonate (EC), 35%;
dimethyl carbonate (EMC), 39%;
diethyl carbonate (DEC), 10%;
wherein the additive comprises the following components in percentage by mass:
heptamethyldisilazane (7-HMDS), 0.5%;
diphenyldiethoxysilane (DPDS), 0.5%;
n, N Dimethylformamide (DMF), 0.5%;
and a negative film forming additive VC (vanadium oxide) accounting for 1 percent.
The preparation method of the electrolyte comprises the following steps:
firstly, preparing lithium salt, a solvent and an additive in advance according to a preset mass ratio;
a second step of adding a lithium salt and an additive to the solvent;
and thirdly, uniformly stirring by a stirrer to obtain the electrolyte.
Comparative example 1
An electrolyte comprising the following components:
a lithium salt;
an organic solvent;
an additive.
Wherein the lithium salt comprises the following components in mass ratio, and the mass ratio is the ratio of the lithium salt to the electrolyte:
lithium hexafluorophosphate (LiPF) 6 ),13%;
Lithium difluorooxalato borate (LiDFOB), 0.5%;
wherein the organic solvent comprises the following components in percentage by mass:
ethylene Carbonate (EC), 35.5%;
ethyl Methyl Carbonate (EMC), 39.5%;
diethyl carbonate (DEC), 10.5%;
wherein the additive comprises the following components in percentage by mass:
and a negative film forming additive VC (vanadium oxide) accounting for 1 percent.
The preparation method of the electrolyte comprises the following steps:
firstly, preparing lithium salt, a solvent and an additive in advance according to a preset mass ratio;
a second step of adding a lithium salt and an additive to the solvent;
and thirdly, uniformly stirring by a stirrer to obtain the electrolyte.
Comparative example 2
An electrolyte comprising the following components:
a lithium salt;
an organic solvent;
an additive.
Wherein the lithium salt comprises the following components in mass ratio, and the mass ratio is the ratio of the lithium salt to the electrolyte:
lithium hexafluorophosphate (LiPF) 6 ),13%;
Lithium difluorooxalato borate (LiDFOB), 0.5%;
wherein the organic solvent comprises the following components in percentage by mass:
ethylene Carbonate (EC), 35%;
methyl ethyl carbonate (EMC), 39%;
diethyl carbonate (DEC), 10%;
wherein the additive comprises the following components in percentage by mass:
heptamethyldisilazane (7-HMDS), 0.5%;
n, N Dimethylformamide (DMF), 0.5%;
and a negative film forming additive VC (vanadium oxide) accounting for 1 percent.
The preparation method of the electrolyte comprises the following steps:
firstly, preparing lithium salt, a solvent and an additive in advance according to a preset mass ratio;
a second step of adding a lithium salt and an additive to the solvent;
and thirdly, uniformly stirring by a stirrer to obtain the electrolyte.
Comparative example 3
Comparative example 3 differs from example 1 in that: comparative example 3 the diphenyldiethoxysilane of example 1 was replaced by phenyltriethoxysilane, an additive which is also silane.
An electrolyte comprising the following components:
a lithium salt;
an organic solvent;
an additive.
Wherein the lithium salt comprises the following components in mass ratio, and the mass ratio is the ratio of the lithium salt to the electrolyte:
lithium hexafluorophosphate (LiPF) 6 ),13%;
Lithium difluorooxalato borate (LiDFOB), 0.5%;
wherein the organic solvent comprises the following components in percentage by mass:
ethylene Carbonate (EC), 35%;
methyl ethyl carbonate (EMC), 39%;
diethyl carbonate (DEC), 10%;
wherein the additive comprises the following components in percentage by mass:
heptamethyldisilazane (7-HMDS), 0.5%;
phenyl triethoxysilane, 0.5%;
n, N Dimethylformamide (DMF), 0.5%;
and a negative film forming additive VC (vanadium oxide) accounting for 1 percent.
The preparation method of the electrolyte comprises the following steps:
firstly, preparing lithium salt, a solvent and an additive in advance according to a preset mass ratio;
a second step of adding a lithium salt and an additive to the solvent;
and thirdly, uniformly stirring by a stirrer to obtain the electrolyte.
Performance test:
electrolyte solutions prepared in examples 1 to 7 and comparative examples 1 to 3 were sequentially prepared to prepare lithium iron manganese phosphate (LMFP) batteries.
Performance tests were performed on the batteries prepared from the electrolytes of examples 1 to 7 and comparative examples 1 to 3.
The test method is as follows:
normal temperature 1C/1C cycle test experiment: the batteries obtained in examples 1 to 7 and comparative examples 1 to 3 were charged at 1.0C to a limiting voltage of 4.5V, then charged at constant voltage to a cutoff current of 0.01C, left to stand for 5 minutes, and then discharged at 1.0C to a cutoff voltage of 2.5V, left to stand for 5 minutes, and subjected to 1000-cycle according to the above-mentioned steps.
High temperature cycle performance test: the soft pack batteries obtained in each of the examples and comparative examples were subjected to a charge-discharge cycle test at 45.+ -. 2 ℃ at a charge-discharge rate of 1C/C in the range of 2.5-4.2V, and the first-week discharge specific capacity and the discharge specific capacity after 500-week cycle of the batteries were recorded. Capacity retention for 500 weeks = discharge specific capacity for 500 weeks/discharge specific capacity for first week 100%.
High temperature storage performance test: the soft pack batteries obtained in each of the examples and comparative examples were subjected to a charge-discharge test at a charge-discharge rate of 1C/1C in the range of 2.5 to 4.2V at 60±2 ℃ and the first week discharge specific capacity of the battery was recorded, followed by storage at 60±2 ℃ for 35 days, and again subjected to a charge-discharge test and the discharge specific capacity was recorded. High-temperature storage capacity retention = discharge specific capacity after 7 days/first week discharge specific capacity 100%.
Normal temperature DCR test: the secondary batteries 1C obtained in each of the examples and comparative examples were charged to 4.2V at 25±2 ℃, discharged at 1C capacity for 30min, adjusted to 50% SOC, and then subjected to 5C constant current pulse discharge for 10s, and after 50% SOC was adjusted by the above-mentioned SOC adjustment method, the secondary batteries were recharged for 10s, and dcr= (voltage before pulse discharge-voltage after pulse discharge)/discharge current of 100% was calculated. Wherein SOC (state of charge) refers to the current capacity state of the secondary battery. 100% SOC is fully charged within the design operating range.
Low temperature DCR test: the secondary batteries 1C obtained in each of the examples and comparative examples were charged to 4.2V at-20±2 ℃, discharged at 1C capacity for 30min, adjusted to 50% SOC, and then subjected to 0.5C constant current pulse discharge for 10s, and 50% SOC was adjusted according to the above-mentioned SOC adjustment method, and then charged for 10s, to calculate dcr= (voltage before pulse discharge-voltage after pulse discharge)/discharge current of 100%.
The test results are shown in Table 1.
TABLE 1
From the above examples 1, 2, 3, 4 and comparative example 1, it is understood that when the addition amounts of the three additives are all 2%, the battery has the best 25 ℃ cycle and 45 ℃ cycle performance and the capacity retention rate is the highest when stored at 60 ℃ for 35 days; the lowest DCR at normal and low temperatures indicates that the better the rate capability of the battery.
As is clear from examples 1 and 2, the addition of 0.5% diphenyldiethoxysilane (DPDS) can improve the high and low temperature performance of the battery.
As is clear from examples 5, 6, and 7 and comparative example 1, the high and low temperature performance of the battery is more excellent as the amount of diphenyldiethoxysilane (DPDS) added is increased (0.5% -2%).
As is clear from examples 1 and 3, the addition of phenyltriethoxysilane, which is also a siloxane compound, does not achieve the purpose of optimizing the battery cycle performance and the high temperature storage performance.
This is because 7-HMDS not only improves the cycle performance of lithium ion batteries excellently, but also stabilizes the morphology of lithium iron manganese phosphate batteries by suppressing dissolution of Mn by scavenging HF in the electrolyte; the diphenyl diethoxy silane (DPDS) mainly forms a protective film on the surfaces of the positive electrode and the negative electrode, inhibits the dissolution of metal ions of the positive electrode, can obviously inhibit the decomposition of electrolyte and improve the high-temperature storage performance of the battery at high temperature; the lone pair of the N, N Dimethylformamide (DMF) of the additive is combined with the electronic structure of PF5 in the electrolyte, thereby further preventing the side reaction of the electrolyte and the corrosion of electrode materials, and having important significance for promoting the large-scale application of the lithium ion battery at high temperature.
In conclusion, according to analysis, through the synergistic effect generated by using the heptamethyldisilazane (7-HMDS), the diphenyldiethoxysilane (DPDS) and the N, N-Dimethylformamide (DMF), the lithium iron manganese phosphate battery has excellent cycle performance and high and low temperature performance in the voltage range of 2.5V-4.5V, so that the lithium iron manganese phosphate battery has wide application prospect in lithium iron manganese phosphate positive electrode system lithium batteries.
The foregoing is merely exemplary embodiments of the present invention and are not intended to limit the scope of the present invention, and all equivalent modifications made by the present invention or direct or indirect application in the relevant art are intended to be included in the scope of the present invention.

Claims (10)

1. An electrolyte, characterized in that: the composition comprises the following components:
a lithium salt;
an organic solvent;
an additive;
the additive comprises at least one of vanadium oxide, heptamethyldisilazane, diphenyldiethoxysilane, N-dimethylformamide, and at least vanadium oxide and diphenyldiethoxysilane.
2. An electrolyte according to claim 1, wherein: the mass ratio of the additive to the total mass of the electrolyte is 1-5%.
3. An electrolyte according to claim 2, wherein: the additive comprises heptamethyldisilazane, diphenyl diethoxy silane and N, N-dimethylformamide, wherein the mass ratio of the heptamethyldisilazane, the diphenyl diethoxy silane and the N, N-dimethylformamide to the total mass of the electrolyte is 1.5-2%.
4. An electrolyte according to claim 2, wherein: the diphenyl diethoxy silane accounts for 0.5-2% of the total mass of the electrolyte.
5. An electrolyte according to claim 4, wherein: the mass ratio of the diphenyl diethoxy silane to the total mass of the electrolyte is 0.5-0.6%.
6. An electrolyte according to claim 1, wherein: the lithium salt comprises at least one of lithium hexafluorophosphate, lithium bis (fluoromethylsulfonimide), lithium difluoro (oxalato) borate and lithium difluoro (phospho) phosphate.
7. An electrolyte according to claim 1, wherein: the organic solvent includes at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, dimethyl carbonate and diethyl carbonate.
8. An electrolyte according to claim 1, wherein: the mass ratio of the lithium salt to the organic solvent is 10-20:60-85.
9. A method for preparing an electrolyte according to any one of claims 1 to 8, characterized in that: the method comprises the following steps:
mixing lithium salt and additive in organic solvent to obtain the electrolyte.
10. A lithium iron manganese phosphate battery is characterized in that: comprising an electrolyte according to any one of claims 1 to 8.
CN202311812307.7A 2023-12-27 2023-12-27 Lithium iron manganese phosphate battery adaptive electrolyte and preparation method and application thereof Pending CN117650275A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202311812307.7A CN117650275A (en) 2023-12-27 2023-12-27 Lithium iron manganese phosphate battery adaptive electrolyte and preparation method and application thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202311812307.7A CN117650275A (en) 2023-12-27 2023-12-27 Lithium iron manganese phosphate battery adaptive electrolyte and preparation method and application thereof

Publications (1)

Publication Number Publication Date
CN117650275A true CN117650275A (en) 2024-03-05

Family

ID=90045166

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202311812307.7A Pending CN117650275A (en) 2023-12-27 2023-12-27 Lithium iron manganese phosphate battery adaptive electrolyte and preparation method and application thereof

Country Status (1)

Country Link
CN (1) CN117650275A (en)

Similar Documents

Publication Publication Date Title
CN109888389B (en) Ternary lithium ion battery non-aqueous electrolyte and high-nickel ternary lithium ion battery containing electrolyte
CN106058155B (en) Lithium ion battery
CN109148951B (en) Electrolyte and lithium ion battery
CN110970662B (en) Non-aqueous electrolyte and lithium ion battery
CN112216862A (en) High-nickel ternary lithium ion battery electrolyte and ternary lithium ion battery
CN110970664A (en) Non-aqueous electrolyte and lithium ion battery
CN115911560A (en) Electrolyte, secondary battery and electric equipment
EP4228028A1 (en) Positive electrode composite material for lithium ion secondary battery, and lithium ion secondary battery
CN110970652A (en) Non-aqueous electrolyte and lithium ion battery
CN111668547B (en) Nonaqueous electrolyte solution and electricity storage device using same
CN109411815A (en) Lithium secondary battery including electrolyte additive and the method for preparing lithium secondary battery
CN111883841A (en) Lithium ion battery non-aqueous electrolyte and lithium ion battery
CN116914245A (en) Electrolyte and battery comprising same
EP3832771A1 (en) Non-aqueous electrolyte, lithium-ion battery, battery module, battery pack and device
CN116646598A (en) Electrolyte and secondary battery
CN112713304A (en) Electrolyte and lithium ion battery with same
CN113972398B (en) Nonaqueous electrolyte and nonaqueous electrolyte battery using same
CN110970663A (en) Non-aqueous electrolyte and lithium ion battery
CN115332626A (en) Electrolyte and battery comprising same
CN111244550B (en) Lithium ion battery electrolyte additive for high-nickel system, electrolyte and battery
EP3879616B1 (en) Electrolyte for lithium secondary battery and lithium secondary battery including the same
CN117650275A (en) Lithium iron manganese phosphate battery adaptive electrolyte and preparation method and application thereof
CN114464889A (en) Non-aqueous electrolyte for high-voltage lithium ion battery and lithium ion battery thereof
KR20230129746A (en) Nonaqueous electrolyte composition and lithium secondary battery containing the same
CN110970659B (en) Non-aqueous electrolyte and lithium ion battery

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination