CN105244538A - Lithium ion secondary battery and electrolyte thereof - Google Patents
Lithium ion secondary battery and electrolyte thereof Download PDFInfo
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- CN105244538A CN105244538A CN201410322843.3A CN201410322843A CN105244538A CN 105244538 A CN105244538 A CN 105244538A CN 201410322843 A CN201410322843 A CN 201410322843A CN 105244538 A CN105244538 A CN 105244538A
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- rechargeable battery
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The invention provides a lithium ion secondary battery and an electrolyte thereof. The electrolyte of the lithium ion secondary battery comprises lithium salt, a nonaqueous organic solvent and an additive. The additive comprises a diisocyanate compound, containing ether bonds, which is of a formula 1 structure and/or a formula 2 structure; in the formula 1, m, n and p are integers of 1 to 4 respectively; in the formula 2, x and y are integers of 1 to 4 respectively; and the weight percentage content of the diisocyanate compound, containing ether bonds, which is of the formula 1 structure and/or the formula 2 structure in the electrode of the lithium ion secondary battery is 0.1% to 2.5%. The lithium ion secondary battery comprises a positive plate, a negative plate, an isolating membrane arranged between the positive plate and the negative plate at an interval, and the electrode. The lithium ion secondary battery provided by the invention has high high-temperature storage performance, normal-temperature cycle performance and high-temperature cycle performance under high voltage.
Description
Technical field
The present invention relates to cell art, particularly relate to a kind of lithium rechargeable battery and electrolyte thereof.
Background technology
Lithium rechargeable battery has that operating voltage is high, the life-span is long and the advantage such as charging rate is fast, but along with the development of technology, people require that lithium rechargeable battery has higher energy density.At present in order to improve the energy density of lithium rechargeable battery further, mainly improving the charge cutoff voltage of lithium rechargeable battery, make positive pole deviate from more a high proportion of lithium ion thus obtain higher capacity, reach the object improving energy density.When but identical positive active material is charged to higher cut-ff voltage, also can improve the oxidability of positive pole, thus make the problem of oxidation of electrolyte even more serious.Particularly under high voltage fully charged state, the negative pole of lithium rechargeable battery has high reproducibility, just has high oxidative.
In actual use, under the factor such as lasting use heating, ambient temperature rising of electronic product all may make lithium rechargeable battery be in the condition of high temperature.At high temperature, the positive pole of lithium rechargeable battery and the reactivity of negative pole strengthen further, cause the positive pole of lithium rechargeable battery, react between negative pole and electrolyte, produce gas, thus cause lithium rechargeable battery to expand.This not only causes the damage of lithium rechargeable battery, also can cause the damage of the equipment using this lithium rechargeable battery simultaneously, because lithium rechargeable battery dilatancy causes inside battery to be short-circuited or battery packages bursts and causes flammable electrolyte to be revealed time serious, there is the risk causing the security incidents such as fire.Therefore effective technology is needed to solve the decomposition of electrolyte and the problem of lithium rechargeable battery flatulence.
In lithium rechargeable battery, general cyclic carbonate and the linear carbonate of using is as non-aqueous organic solvent, but under high voltage high temperature storage, the non-aqueous organic solvent of lithium rechargeable battery is easily oxidized aerogenesis by positive pole.The Chinese patent application publication No. announced on October 30th, 2013 is that the one that patent discloses of CN103380530A adds hexamethylene diisocyanate (HDI) in the electrolytic solution as additive to improve the method for the high-temperature storage performance of lithium rechargeable battery, but hexamethylene diisocyanate (HDI) can cause the cycle performance of lithium rechargeable battery to be deteriorated.
Summary of the invention
In view of Problems existing in background technology, the object of the present invention is to provide a kind of lithium rechargeable battery and electrolyte thereof, described lithium rechargeable battery has good high-temperature storage performance, normal-temperature circulating performance and high temperature cyclic performance under high voltages.
In order to realize foregoing invention object, in a first aspect of the present invention, the invention provides a kind of electrolyte of lithium rechargeable battery, it comprises: lithium salts; Non-aqueous organic solvent; And additive.Described additive comprises the diisocyanate cpd of the ether-containing key with formula 1 and/or formula 2 structure; In formula 1, m, n, p are respectively the integer of 1 ~ 4; In formula 2, x, y are respectively the integer of 1 ~ 4;
The described mass percentage of diisocyanate cpd in the electrolyte of lithium rechargeable battery with the ether-containing key of formula 1 and/or formula 2 structure is 0.1% ~ 2.5%.
In a second aspect of the present invention, the invention provides a kind of lithium rechargeable battery, it comprises: positive plate, comprises plus plate current-collecting body and is arranged at the positive pole diaphragm containing positive active material on plus plate current-collecting body; Negative plate, comprises negative current collector and is arranged at the cathode membrane containing negative electrode active material on negative current collector; Barrier film, is interval between positive plate and negative plate; And electrolyte.Wherein, described electrolyte is the electrolyte of lithium rechargeable battery according to a first aspect of the present invention.
Beneficial effect of the present invention is as follows:
1. the electrolyte of lithium rechargeable battery of the present invention contains the diisocyanate cpd of the ether-containing key with formula 1 and/or formula 2 structure, it can form one deck passivating film in the pole piece of lithium rechargeable battery, even under high voltages, also effectively can stop the side reaction between pole piece and electrolyte, thus improve the high-temperature storage performance of lithium rechargeable battery.
2. the passivating film that the diisocyanate cpd with the ether-containing key of formula 1 and/or formula 2 structure in the electrolyte of lithium rechargeable battery of the present invention is formed contains more oxygen atom, thus lithium ion can be reduced through resistance during passivating film, improve the interface performance between electrolyte and pole piece, and then improve normal-temperature circulating performance and the high temperature cyclic performance of lithium rechargeable battery.
Embodiment
The following detailed description of lithium rechargeable battery according to the present invention and electrolyte thereof and embodiment, comparative example and test result.
First the electrolyte of lithium rechargeable battery is according to a first aspect of the present invention described.
The electrolyte of lithium rechargeable battery according to a first aspect of the present invention, comprising: lithium salts; Non-aqueous organic solvent; And additive.Described additive comprises the diisocyanate cpd of the ether-containing key with formula 1 and/or formula 2 structure; In formula 1, m, n, p are respectively the integer of 1 ~ 4; In formula 2, x, y are respectively the integer of 1 ~ 4;
The described mass percentage of diisocyanate cpd in the electrolyte of lithium rechargeable battery with the ether-containing key of formula 1 and/or formula 2 structure is 0.1% ~ 2.5%.
Need at this implication of "and/or" of remarking additionally, described in there is the ether-containing key of formula 1 and/or formula 2 structure the mass percentage of diisocyanate cpd in the electrolyte of lithium rechargeable battery refer to the mass percentage of diisocyanate cpd total amount in the electrolyte of lithium rechargeable battery of ether-containing key; In other words, if the diisocyanate cpd of described ether-containing key is only the diisocyanate cpd of the ether-containing key with formula 1 structure, then the mass percentage of diisocyanate cpd in the electrolyte of lithium rechargeable battery with the ether-containing key of formula 1 structure is 0.1% ~ 2.5%; If the diisocyanate cpd of described ether-containing key is only the diisocyanate cpd of the ether-containing key with formula 2 structure, then the mass percentage of diisocyanate cpd in the electrolyte of lithium rechargeable battery with the ether-containing key of formula 2 structure is 0.1% ~ 2.5%; If the diisocyanate cpd of described ether-containing key is the diisocyanate cpd of the ether-containing key with formula 1 structure and formula 2 structure, then the diisocyanate cpd with the ether-containing key of formula 1 structure is 0.1% ~ 2.5% with the mass percentage of summation in the electrolyte of lithium rechargeable battery of the diisocyanate cpd of the ether-containing key with formula 2 structure.
In the present invention, the diisocyanate cpd of the ether-containing key with formula 1 and/or formula 2 structure is joined in the electrolyte of lithium rechargeable battery, lithium rechargeable battery can be made to have good high-temperature storage performance, normal-temperature circulating performance and high temperature cyclic performance.This is that the diisocyanate cpd of ether-containing key owing to having formula 1 and/or formula 2 structure easily forms the comparatively stable passivating film of one deck in pole piece, even under high voltages, also effectively can stop the side reaction between pole piece and electrolyte, thus improve the high-temperature storage performance of lithium rechargeable battery; In addition, the passivating film that the diisocyanate cpd with the ether-containing key of formula 1 and/or formula 2 structure is formed contains more oxygen atom, thus lithium ion can be reduced through resistance during passivating film, improve the interface performance between electrolyte and pole piece, and then improve normal-temperature circulating performance and the high temperature cyclic performance of lithium rechargeable battery.
If there is the mass percentage of the diisocyanate cpd of the ether-containing key of formula 1 and/or formula 2 structure too much (>2.5%) in electrolyte, the diisocyanate cpd then with the ether-containing key of formula 1 and/or formula 2 structure is blocked up at pole piece formation passivating film, the impedance of pole piece is increased, worsen the interface performance between pole piece and electrolyte, reduce the conductibility of lithium ion at the interface of pole piece and electrolyte, thus the normal-temperature circulating performance of deterioration lithium rechargeable battery and high temperature cyclic performance.If the mass percentage in electrolyte with the diisocyanate cpd of the ether-containing key of formula 1 and/or formula 2 structure is very few (<0.1%), the passivation that the diisocyanate cpd then with the ether-containing key of formula 1 and/or formula 2 structure is formed in pole piece is lepthymenia, effectively can not stop the side reaction between electrolyte and pole piece, thus effectively can not improve the high-temperature storage performance of lithium rechargeable battery, normal-temperature circulating performance and high temperature cyclic performance.
In the electrolyte of lithium rechargeable battery described according to a first aspect of the present invention, described lithium salts can be selected from LiN (C
af2
a+1sO
2) (C
bf
2b+1sO
2), LiPF
6, LiBF
4, LiBOB, LiAsF
6, Li (CF
3sO
2)
2n, LiCF
3sO
3and LiClO
4in at least one, wherein, a, b are natural number.
In the electrolyte of lithium rechargeable battery described according to a first aspect of the present invention, the concentration of described lithium salts can be 0.5M ~ 2M.
In the electrolyte of lithium rechargeable battery described according to a first aspect of the present invention, described non-aqueous organic solvent can comprise the combination of cyclic carbonate and linear carbonate.Described cyclic carbonate has higher dielectric constant, can very well and lithium ion form solvation lithium ion molecule; Described linear carbonate has lower viscosity, thus is conducive to the conduction of lithium ion.
In the electrolyte of lithium rechargeable battery described according to a first aspect of the present invention, described cyclic carbonate can be selected from least one in ethylene carbonate (EC), propene carbonate (PC) and butylene (BC); Described linear carbonate can be selected from least one in dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl ethyl carbonate (EMC), methyl propyl carbonate (MPC) and ethyl propyl carbonic acid ester (EPC).
In the electrolyte of lithium rechargeable battery described according to a first aspect of the present invention, the mass percentage of described cyclic carbonate in the electrolyte of lithium rechargeable battery can be 10% ~ 70%; The mass percentage of described linear carbonate in the electrolyte of lithium rechargeable battery can be 15% ~ 80%.
In the electrolyte of lithium rechargeable battery described according to a first aspect of the present invention, described in there is the ether-containing key of formula 1 structure diisocyanate cpd can be selected from and there is molecular formula 1-1 structure at least one in the compound of molecular formula 1-20 structure,
In the electrolyte of lithium rechargeable battery described according to a first aspect of the present invention, described in there is the ether-containing key of formula 2 structure diisocyanate cpd can be selected from and there is molecular formula 2-1 structure at least one in the compound of molecular formula 2-6 structure,
In the electrolyte of lithium rechargeable battery described according to a first aspect of the present invention, described in there is the ether-containing key of formula 1 and/or formula 2 structure the mass percentage of diisocyanate cpd in the electrolyte of lithium rechargeable battery can be 0.2% ~ 2%.Namely, if the diisocyanate cpd of described ether-containing key is only the diisocyanate cpd of the ether-containing key with formula 1 structure, then the mass percentage of diisocyanate cpd in the electrolyte of lithium rechargeable battery with the ether-containing key of formula 1 structure is 0.2% ~ 2%; If the diisocyanate cpd of described ether-containing key is only the diisocyanate cpd of the ether-containing key with formula 2 structure, then the mass percentage of diisocyanate cpd in the electrolyte of lithium rechargeable battery with the ether-containing key of formula 2 structure is 0.2% ~ 2%; If the diisocyanate cpd of described ether-containing key is the diisocyanate cpd of the ether-containing key with formula 1 structure and formula 2 structure, then the diisocyanate cpd with the ether-containing key of formula 1 structure is 0.2% ~ 2% with the mass percentage of summation in the electrolyte of lithium rechargeable battery of the diisocyanate cpd of the ether-containing key with formula 2 structure.
In the electrolyte of lithium rechargeable battery described according to a first aspect of the present invention, also comprise: PS (PS).
In the electrolyte of lithium rechargeable battery described according to a first aspect of the present invention, the mass percentage of described PS in the electrolyte of lithium rechargeable battery can be 0.1% ~ 5%.
Secondly lithium rechargeable battery is according to a second aspect of the present invention described.
Lithium rechargeable battery according to a second aspect of the present invention, comprising: positive plate, comprises plus plate current-collecting body and is arranged at the positive pole diaphragm containing positive active material on plus plate current-collecting body; Negative plate, comprises negative current collector and is arranged at the cathode membrane containing negative electrode active material on negative current collector; Barrier film, is interval between positive plate and negative plate; And electrolyte.Wherein, described electrolyte is the electrolyte of lithium rechargeable battery according to a first aspect of the present invention.
In lithium rechargeable battery described according to a second aspect of the present invention, the charging of described lithium rechargeable battery can be 4.35V ~ 4.9V by voltage.
In lithium rechargeable battery described according to a second aspect of the present invention, described positive active material can be selected from Li
xco
ym
1-ya
2, LiMn
zn
2-zo
4in at least one, wherein, 0.97≤x≤1.06,0≤y≤1,0≤z≤2, M is selected from least one in Ni, Fe, Mg, Al, Ti, V, Ge, Zr, Mn, Cr, A is selected from least one in O, F, S, P, and N is selected from least one in Co, Ni, Fe.The diisocyanate cpd with the ether-containing key of formula 1 and/or formula 2 structure of the present invention easily forms the comparatively stable passivating film of one deck in pole piece, the stripping of transition metal in positive active material (Mn, Co, Ni etc.) can be stoped simultaneously, thus more effectively improve the high-temperature storage performance of lithium rechargeable battery.
Following explanation is according to the embodiment of lithium rechargeable battery of the present invention and electrolyte thereof and comparative example.
Embodiment 1
(1) preparation of the positive plate of lithium rechargeable battery
By positive active material cobalt acid lithium LiCoO
2, conductive agent Super-P, bonding agent PVDF in mass ratio 96:2:2 join in solvent N-methyl pyrilidone (NMP) to mix and make anode sizing agent, anode sizing agent is coated in current collector aluminum foil, afterwards through colding pressing, drying (forming positive pole diaphragm), soldering polar ear, make the positive plate of lithium rechargeable battery.
(2) preparation of the negative plate of lithium rechargeable battery
By negative electrode active material graphite, conductive agent Super-P, thickener CMC, bonding agent SBR in mass ratio 96.5:1.0:1.0:1.5 join in solvent deionized water to mix and make cathode size, cathode size is coated on copper foil of affluxion body, afterwards through colding pressing, drying (formation cathode membrane), soldering polar ear, make the negative plate of lithium rechargeable battery.
(3) preparation of the electrolyte of lithium rechargeable battery
The electrolyte of lithium rechargeable battery take concentration as 1M lithium hexafluoro phosphate (LiPF
6) be lithium salts, with the mixture of ethylene carbonate (EC), propene carbonate (PC) and diethyl carbonate (DEC) for non-aqueous organic solvent, wherein the mass ratio of each carbonic ester is EC:PC:DEC=30:30:40.In addition, also containing additive in electrolyte, additive to be the mass percentage in the electrolyte of lithium rechargeable battery be 0.1% the compound with molecular formula 1-2 structure.
(4) preparation of lithium rechargeable battery
By the positive plate of the lithium rechargeable battery of preparation, negative plate and barrier film (polyethylene, PE) battery core is made into through winding process, inject electrolyte after vacuum bakeout, leave standstill 24 hours, use the constant current charge of 0.1C to 4.4V (charge cutoff voltage) afterwards, then drop to 0.05C with 4.4V constant voltage charge to electric current; Then be discharged to 3.0V with the constant current of 0.5C, repeat 2 discharge and recharges, finally again with the constant current charge of 0.5C to 3.9V, complete the preparation of lithium rechargeable battery.
Embodiment 2
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive to be the mass percentage in the electrolyte of lithium rechargeable battery be 0.2% the compound with molecular formula 1-2 structure.
Embodiment 3
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive to be the mass percentage in the electrolyte of lithium rechargeable battery be 0.5% the compound with molecular formula 1-2 structure.
Embodiment 4
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive to be the mass percentage in the electrolyte of lithium rechargeable battery be 1.0% the compound with molecular formula 1-2 structure.
Embodiment 5
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive to be the mass percentage in the electrolyte of lithium rechargeable battery be 1.5% the compound with molecular formula 1-2 structure.
Embodiment 6
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive to be the mass percentage in the electrolyte of lithium rechargeable battery be 2.0% the compound with molecular formula 1-2 structure.
Embodiment 7
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive to be the mass percentage in the electrolyte of lithium rechargeable battery be 2.5% the compound with molecular formula 1-2 structure.
Embodiment 8
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive to be the mass percentage in the electrolyte of lithium rechargeable battery be 1.0% the compound with molecular formula 2-1 structure.
Embodiment 9
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive to be the mass percentage in the electrolyte of lithium rechargeable battery be 1.0% the compound with molecular formula 2-6 structure.
Embodiment 10
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive to be the mass percentage in the electrolyte of lithium rechargeable battery be 1.0% the compound with molecular formula 1-7 structure.
Embodiment 11
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive to be the mass percentage in the electrolyte of lithium rechargeable battery be 1.0% the compound with molecular formula 1-9 structure.
Embodiment 12
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive to be the mass percentage in the electrolyte of lithium rechargeable battery be 1.0% the compound with molecular formula 1-16 structure.
Embodiment 13
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive is the mass percentage in the electrolyte of lithium rechargeable battery to be the compound with molecular formula 1-2 structure of 0.5% and the mass percentage in the electrolyte of lithium rechargeable battery be 0.5% the compound with molecular formula 2-1 structure.
Embodiment 14
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive is the mass percentage in the electrolyte of lithium rechargeable battery to be the compound with molecular formula 1-2 structure of 0.5% and the mass percentage in the electrolyte of lithium rechargeable battery be 0.5% the compound with molecular formula 2-6 structure.
Embodiment 15
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive is the mass percentage in the electrolyte of lithium rechargeable battery to be the compound with molecular formula 1-2 structure of 0.5% and the mass percentage in the electrolyte of lithium rechargeable battery be 0.5% the compound with molecular formula 1-7 structure.
Embodiment 16
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive is the mass percentage in the electrolyte of lithium rechargeable battery to be the compound with molecular formula 1-2 structure of 0.5% and the mass percentage in the electrolyte of lithium rechargeable battery be 0.5% the compound with molecular formula 1-9 structure.
Embodiment 17
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive is the mass percentage in the electrolyte of lithium rechargeable battery to be the compound with molecular formula 1-2 structure of 0.5% and the mass percentage in the electrolyte of lithium rechargeable battery be 0.5% the compound with molecular formula 1-16 structure.
Embodiment 18
Method according to embodiment 1 prepares lithium rechargeable battery, and just in the preparation (i.e. step (1)) of the positive plate of lithium rechargeable battery, positive active material is LiNi
1/3co
1/3mn
1/3o
2.
Embodiment 19
Method according to embodiment 2 prepares lithium rechargeable battery, and just in the preparation (i.e. step (1)) of the positive plate of lithium rechargeable battery, positive active material is LiNi
1/3co
1/3mn
1/3o
2.
Embodiment 20
Method according to embodiment 3 prepares lithium rechargeable battery, and just in the preparation (i.e. step (1)) of the positive plate of lithium rechargeable battery, positive active material is LiNi
1/3co
1/3mn
1/3o
2.
Embodiment 21
Method according to embodiment 4 prepares lithium rechargeable battery, and just in the preparation (i.e. step (1)) of the positive plate of lithium rechargeable battery, positive active material is LiNi
1/3co
1/3mn
1/3o
2.
Embodiment 22
Method according to embodiment 5 prepares lithium rechargeable battery, and just in the preparation (i.e. step (1)) of the positive plate of lithium rechargeable battery, positive active material is LiNi
1/3co
1/3mn
1/3o
2.
Embodiment 23
Method according to embodiment 6 prepares lithium rechargeable battery, and just in the preparation (i.e. step (1)) of the positive plate of lithium rechargeable battery, positive active material is LiNi
1/3co
1/3mn
1/3o
2.
Embodiment 24
Method according to embodiment 7 prepares lithium rechargeable battery, and just in the preparation (i.e. step (1)) of the positive plate of the electrolyte of lithium rechargeable battery, positive active material is LiNi
1/3co
1/3mn
1/3o
2.
Embodiment 25
Method according to embodiment 8 prepares lithium rechargeable battery, and just in the preparation (i.e. step (1)) of the positive plate of lithium rechargeable battery, positive active material is LiNi
1/3co
1/3mn
1/3o
2.
Embodiment 26
Method according to embodiment 9 prepares lithium rechargeable battery, and just in the preparation (i.e. step (1)) of the positive plate of lithium rechargeable battery, positive active material is LiNi
1/3co
1/3mn
1/3o
2.
Embodiment 27
Method according to embodiment 10 prepares lithium rechargeable battery, and just in the preparation (i.e. step (1)) of the positive plate of lithium rechargeable battery, positive active material is LiNi
1/3co
1/3mn
1/3o
2.
Embodiment 28
Method according to embodiment 11 prepares lithium rechargeable battery, and just in the preparation (i.e. step (1)) of the positive plate of lithium rechargeable battery, positive active material is LiNi
1/3co
1/3mn
1/3o
2.
Embodiment 29
Method according to embodiment 12 prepares lithium rechargeable battery, and just in the preparation (i.e. step (1)) of the positive plate of lithium rechargeable battery, positive active material is LiNi
1/3co
1/3mn
1/3o
2.
Embodiment 30
Method according to embodiment 3 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, the electrolyte of lithium rechargeable battery is with the mixture of ethylene carbonate (EC), propene carbonate (PC), diethyl carbonate (DEC) and methyl ethyl carbonate (EMC) for non-aqueous organic solvent, and wherein the mass ratio of each carbonic ester is EC:PC:DEC:EMC=20:20:20:40.
Embodiment 31
Method according to embodiment 4 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, the electrolyte of lithium rechargeable battery is with the mixture of ethylene carbonate (EC), propene carbonate (PC), diethyl carbonate (DEC) and methyl ethyl carbonate (EMC) for non-aqueous organic solvent, and wherein the mass ratio of each carbonic ester is EC:PC:DEC:EMC=20:20:20:40.
Embodiment 32
Method according to embodiment 5 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, the electrolyte of lithium rechargeable battery is with the mixture of ethylene carbonate (EC), propene carbonate (PC), diethyl carbonate (DEC) and methyl ethyl carbonate (EMC) for non-aqueous organic solvent, and wherein the mass ratio of each carbonic ester is EC:PC:DEC:EMC=20:20:20:40.
Embodiment 33
Method according to embodiment 6 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, the electrolyte of lithium rechargeable battery is with the mixture of ethylene carbonate (EC), propene carbonate (PC), diethyl carbonate (DEC) and methyl ethyl carbonate (EMC) for non-aqueous organic solvent, and wherein the mass ratio of each carbonic ester is EC:PC:DEC:EMC=20:20:20:40.
Embodiment 34
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive is the mass percentage in the electrolyte of lithium rechargeable battery be the compound with molecular formula 1-2 structure of 0.5% and the mass percentage in the electrolyte of lithium rechargeable battery is the PS of 0.1%.
Embodiment 35
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive is the mass percentage in the electrolyte of lithium rechargeable battery be the compound with molecular formula 1-2 structure of 0.5% and the mass percentage in the electrolyte of lithium rechargeable battery is the PS of 1.0%.
Embodiment 36
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive is the mass percentage in the electrolyte of lithium rechargeable battery be the compound with molecular formula 1-2 structure of 0.5% and the mass percentage in the electrolyte of lithium rechargeable battery is the PS of 3.0%.
Embodiment 37
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive is the mass percentage in the electrolyte of lithium rechargeable battery be the compound with molecular formula 1-2 structure of 0.5% and the mass percentage in the electrolyte of lithium rechargeable battery is the PS of 5.0%.
Embodiment 38
Method according to embodiment 21 prepares lithium rechargeable battery, except following difference:
In the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, the mass ratio of each carbonic ester is EC:PC:DEC=20:20:60;
In the preparation (i.e. step (4)) of lithium rechargeable battery, the charge cutoff voltage of lithium rechargeable battery is 4.35V.
Embodiment 39
Method according to embodiment 38 prepares lithium rechargeable battery, and just in the preparation (i.e. step (4)) of lithium rechargeable battery, the charge cutoff voltage of lithium rechargeable battery is 4.4V.
Embodiment 40
Method according to embodiment 38 prepares lithium rechargeable battery, and just in the preparation (i.e. step (4)) of lithium rechargeable battery, the charge cutoff voltage of lithium rechargeable battery is 4.5V.
Embodiment 41
Method according to embodiment 38 prepares lithium rechargeable battery, and just in the preparation (i.e. step (4)) of lithium rechargeable battery, the charge cutoff voltage of lithium rechargeable battery is 4.6V.
Embodiment 42
Method according to embodiment 38 prepares lithium rechargeable battery, except following difference:
In the preparation (i.e. step (1)) of the positive plate of lithium rechargeable battery, positive active material is LiNi
0.5mn
1.5o
4;
In the preparation (i.e. step (4)) of lithium rechargeable battery, the charge cutoff voltage of lithium rechargeable battery is 4.7V.
Embodiment 43
Method according to embodiment 42 prepares lithium rechargeable battery, and just in the preparation (i.e. step (4)) of lithium rechargeable battery, the charge cutoff voltage of lithium rechargeable battery is 4.8V.
Embodiment 44
Method according to embodiment 42 prepares lithium rechargeable battery, and just in the preparation (i.e. step (4)) of lithium rechargeable battery, the charge cutoff voltage of lithium rechargeable battery is 4.9V.
Comparative example 1
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, does not add any additive.
Comparative example 2
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive to be the mass percentage in the electrolyte of lithium rechargeable battery be 0.01% the compound with molecular formula 1-2 structure.
Comparative example 3
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive to be the mass percentage in the electrolyte of lithium rechargeable battery be 5.0% the compound with molecular formula 1-2 structure.
Comparative example 4
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive to be the mass percentage in the electrolyte of lithium rechargeable battery be 1.0% hexamethylene diisocyanate (HDI).
Comparative example 5
Method according to embodiment 18 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, does not add any additive.
Comparative example 6
Method according to embodiment 18 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive to be the mass percentage in the electrolyte of lithium rechargeable battery be 0.01% the compound with molecular formula 1-2 structure.
Comparative example 7
Method according to embodiment 18 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive to be the mass percentage in the electrolyte of lithium rechargeable battery be 5.0% the compound with molecular formula 1-2 structure.
Comparative example 8
Method according to embodiment 18 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive to be the mass percentage in the electrolyte of lithium rechargeable battery be 1.0% hexamethylene diisocyanate (HDI).
Comparative example 9
Method according to embodiment 1 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive is the mass percentage in the electrolyte of lithium rechargeable battery is the PS of 1.0%.
Comparative example 10
Method according to embodiment 38 prepares lithium rechargeable battery, in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive is the mass percentage in the electrolyte of lithium rechargeable battery is the PS of 2.0%.
Comparative example 11
Method according to embodiment 39 prepares lithium rechargeable battery, except following difference:
In the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive is the mass percentage in the electrolyte of lithium rechargeable battery is the PS of 2.0%.
Comparative example 12
Method according to embodiment 40 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive is the mass percentage in the electrolyte of lithium rechargeable battery is the PS of 2.0%.
Comparative example 13
Method according to embodiment 41 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive is the mass percentage in the electrolyte of lithium rechargeable battery is the PS of 2.0%.
Comparative example 14
Method according to embodiment 42 prepares lithium rechargeable battery, just in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive is the mass percentage in the electrolyte of lithium rechargeable battery is the PS of 2.0%.
Comparative example 15
Method according to embodiment 43 prepares lithium rechargeable battery, in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive is the mass percentage in the electrolyte of lithium rechargeable battery is the PS of 2.0%.
Comparative example 16
Method according to embodiment 44 prepares lithium rechargeable battery, in the preparation (i.e. step (3)) of the electrolyte of lithium rechargeable battery, additive is the mass percentage in the electrolyte of lithium rechargeable battery is the PS of 2.0%.
Finally provide the lithium rechargeable battery of embodiment 1-44 and comparative example 1-16 and the performance test process of electrolyte thereof and test result.
(1) the high-temperature storage performance test of lithium rechargeable battery
At 25 DEG C, first with the constant current of 0.5C, its respective charge cutoff voltage is charged to lithium rechargeable battery, under its respective charge cutoff voltage, constant voltage charge is less than 0.05C to electric current further, test its thickness, be designated as the thickness before lithium rechargeable battery high temperature storage, then in 85 DEG C of environment, store 24 hours, again test its thickness, be designated as the thickness after lithium rechargeable battery high temperature storage.
Thickness swelling (%) after lithium rechargeable battery 85 DEG C/24h stores=[thickness before (thickness before the thickness-storage after storage)/storage] × 100%.
At 25 DEG C, first with the constant current of 0.5C, its respective charge cutoff voltage is charged to lithium rechargeable battery, under its respective charge cutoff voltage, constant voltage charge is less than 0.05C to electric current further, test its thickness, be designated as the thickness before lithium rechargeable battery high temperature storage, then in 60 DEG C of environment, store 15 days, again test its thickness, be designated as the thickness after lithium rechargeable battery high temperature storage.
Thickness swelling (%) after lithium rechargeable battery 60 DEG C/15day stores=[thickness before (thickness before the thickness-storage after storage)/storage] × 100%.
(2) the cycle performance test of lithium rechargeable battery
Under 25 DEG C and 45 DEG C of conditions, with the constant current of 0.5C, its respective charge cutoff voltage is charged to lithium rechargeable battery respectively, under its respective charge cutoff voltage, constant voltage charge is less than 0.05C to electric current further, then be discharged to 3.0V with the constant current of 0.5C to lithium rechargeable battery, current discharge capacity is designated as the discharge capacity of lithium rechargeable battery first time circulation; In a manner described cycle charge discharge electrical testing is carried out to lithium rechargeable battery, records the discharge capacity of the 300th circulation.
Capability retention after lithium rechargeable battery 300 circulations=(discharge capacity of the discharge capacity/first time circulation of the 300th circulation) × 100%.
Table 1 provides relevant parameter and the performance test results of embodiment 1-44 and comparative example 1-16.
Next the performance test results of lithium rechargeable battery is analyzed.
(1) test result analysis of the high-temperature storage performance of lithium rechargeable battery
(any additive is not added from embodiment 1-17 and comparative example 1, thickness swelling after 4.4V/85 DEG C/24h stores is 92%, 4.4V/60 DEG C/15day store after thickness swelling be 140%) contrast in can find out, the lithium rechargeable battery that with the addition of the diisocyanate cpd of the ether-containing key with formula 1 and/or formula 2 structure in the electrolyte of lithium rechargeable battery has lower thickness swelling.This is owing to not adding any additive in comparative example 1, very strong oxidizability is just had under high-voltage state, can non-aqueous organic solvent in oxidation electrolyte, cause lithium rechargeable battery aerogenesis, and then lithium rechargeable battery store after thickness swelling too high.And the diisocyanate cpd with the ether-containing key of formula 1 and/or formula 2 structure can form the passivating film of one deck densification in pole piece, active material in prevention pole piece and the side reaction between electrolyte, reduce aerogenesis, thus make lithium rechargeable battery have lower thickness swelling; And the diisocyanate cpd with the ether-containing key of formula 1 and/or formula 2 structure can also react with the water in electrolyte, HF, thus reduce water, side reaction between HF and electrolyte, and then minimizing aerogenesis, therefore lithium rechargeable battery has lower thickness swelling.
As can be seen from the contrast of embodiment 1-7, the compound with molecular formula 1-2 structure of 0.1% ~ 2.5% is added in the electrolyte of lithium rechargeable battery, the passivating film of one deck densification can be formed in pole piece, active material in prevention pole piece and the side reaction between electrolyte, therefore lithium rechargeable battery has lower thickness swelling, and along with have molecular formula 1-2 structure compound mass percentage increase, slightly increase after thickness swelling after thickness swelling after lithium rechargeable battery 4.4V/85 DEG C/24h stores and 4.4V/60 DEG C/15day store all first reduces.But, when the mass percentage of the compound with molecular formula 1-2 structure is too small (comparative example 2), although the high-temperature storage performance of lithium rechargeable battery can be improved, but also do not reach desirable effect, this may be the mass percentage of compound owing to having molecular formula 1-2 structure very little, cause formed passivating film fine and close not, effectively can not stop the side reaction in pole piece between active material and electrolyte, and then thickness swelling after lithium rechargeable battery high temperature storage is still higher.When the mass percentage of the compound with molecular formula 1-2 structure is too high (comparative example 3), the high-temperature storage performance of lithium rechargeable battery worsens, this may be because the too much compound with molecular formula 1-2 structure causes at the passivating film of pole piece formation blocked up, cause interface impedance excessive, effectively can not stop the side reaction between active material in pole piece and electrolyte, cause the thickness swelling after lithium rechargeable battery high temperature storage higher.
As can be seen from the contrast of embodiment 4 and embodiment 8-12, the diisocyanate cpd with the ether-containing key of formula 1 or formula 2 structure of 1% is added in the electrolyte of lithium rechargeable battery, owing to defining fine and close passivating film, prevent the side reaction between active material in pole piece and electrolyte, therefore lithium rechargeable battery has lower thickness swelling, thickness swelling after 4.4V/85 DEG C/24h stores is below 26%, and the thickness swelling after 4.4V/60 DEG C/15day stores is below 32%.
As can be seen from the contrast of embodiment 13-17, the mixture with the diisocyanate cpd of the ether-containing key of formula 1 and formula 2 structure of 1% is added in the electrolyte of lithium rechargeable battery, owing to defining fine and close passivating film, prevent the side reaction between active material in pole piece and electrolyte, therefore lithium rechargeable battery has lower thickness swelling, thickness swelling after 4.4V/85 DEG C/24h stores is below 25%, and the thickness swelling after 4.4V/60 DEG C/15day stores is below 31%.
(any additive is not added from embodiment 18-29 and comparative example 5, thickness swelling after 4.4V/85 DEG C/24h stores is 142%, 4.4V/60 DEG C/15day store after thickness swelling be 98%) contrast in can find out, the lithium rechargeable battery adding the diisocyanate cpd of the ether-containing key with formula 1 or formula 2 structure in the electrolyte of lithium rechargeable battery has lower thickness swelling.This is owing to not adding any additive in comparative example 5, very strong oxidizability is just had under high-voltage state, can non-aqueous organic solvent in oxidation electrolyte, cause lithium rechargeable battery aerogenesis, and then lithium rechargeable battery store after thickness swelling too high.And the diisocyanate cpd with the ether-containing key of formula 1 or formula 2 structure can form the passivating film of one deck densification in pole piece, active material in prevention pole piece and the side reaction between electrolyte, reduce aerogenesis, thus make lithium rechargeable battery have lower thickness swelling; The diisocyanate cpd with the ether-containing key of formula 1 or formula 2 structure effectively can also stop the stripping of transition metal (Mn, Co, Ni etc.) at the passivating film that pole piece is formed, lithium rechargeable battery also can be made to have lower thickness swelling; The diisocyanate cpd with the ether-containing key of formula 1 or formula 2 structure can also react with the water in electrolyte, HF, thus reduces water, side reaction between HF and electrolyte, reduces aerogenesis, lithium rechargeable battery also can be made to have lower thickness swelling; Have after the diisocyanate cpd of the ether-containing key of formula 1 and/or formula 2 structure and HF react, the side reaction between HF and pole piece can also be reduced, reduce the stripping of transition metal (Mn, Co, Ni etc.), make lithium rechargeable battery have lower thickness swelling.
As can be seen from the contrast of embodiment 18-24, the compound with molecular formula 1-2 structure of 0.1% ~ 2.5% is added in the electrolyte of lithium rechargeable battery, the passivating film of one deck densification can be formed in pole piece, active material in prevention pole piece and the side reaction between electrolyte, therefore lithium rechargeable battery has lower thickness swelling, and along with have molecular formula 1-2 structure compound mass percentage increase, slightly increase after thickness swelling after thickness swelling after lithium rechargeable battery 4.4V/85 DEG C/24h stores and 4.4V/60 DEG C/15day store all first reduces.But, when the mass percentage of the compound with molecular formula 1-2 structure is too small (comparative example 6), although the high-temperature storage performance of lithium rechargeable battery can be improved, but also do not reach desirable effect, this may be the mass percentage of compound owing to having molecular formula 1-2 structure very little, cause formed passivating film fine and close not, effectively can not stop the side reaction between active material in pole piece and electrolyte, and due to passivating film fine and close not, can not effectively stop transition metal (Mn, Co, Ni etc.) stripping, and then thickness swelling after lithium rechargeable battery high temperature storage is higher.When the mass percentage of the compound with molecular formula 1-2 structure is too high (comparative example 7), the high-temperature storage performance of lithium rechargeable battery worsens, this may be because the too much compound with molecular formula 1-2 structure causes at the passivating film of pole piece formation blocked up, cause interface impedance excessive, effectively can not stop the side reaction between active material in pole piece and electrolyte, cause the thickness swelling after lithium rechargeable battery high temperature storage higher.
As can be seen from the contrast of embodiment 21 and embodiment 25-29, the diisocyanate cpd with the ether-containing key of formula 1 or formula 2 structure of 1% is added in the electrolyte of lithium rechargeable battery, owing to defining fine and close passivating film, prevent the side reaction between active material in pole piece and electrolyte, therefore lithium rechargeable battery has lower thickness swelling, thickness swelling after 4.4V/85 DEG C/24h stores is below 30%, and the thickness swelling after 4.4V/60 DEG C/15day stores is below 25%.
As can be seen from embodiment 30 with embodiment 3, embodiment 31 with embodiment 4, embodiment 32 with embodiment 5, embodiment 33 with the contrast of embodiment 6, the thickness swelling after the lithium rechargeable battery high temperature storage of embodiment 30-33 is lower.This may be owing to adding EMC in the electrolyte of embodiment 30-33, it has good stability under high temperature high voltage condition, and EC, PC and DEC easy oxidation Decomposition under high temperature high voltage condition, so the high-temperature storage performance of lithium rechargeable battery can be improved to a certain extent with EMC Substitute For Partial EC, PC and DEC.
As can be seen from the contrast of embodiment 3, embodiment 34-37 and comparative example 9, containing have formula 1 structure ether-containing key diisocyanate cpd lithium rechargeable battery electrolyte in add PS again, the high-temperature storage performance of lithium rechargeable battery can be improved.And the high-temperature storage performance containing the lithium rechargeable battery of independent PS is poor, but PS can form passivating film basis at the diisocyanate cpd by the ether-containing key with formula 1 structure forms the stable passivating film of one deck again, passivating film is made to become composite passivation film, this composite passivation film can make the interface between pole piece and electrolyte more stable, and then can improve the high-temperature storage performance of lithium rechargeable battery.It can also be seen that from embodiment 34-37 contrast, along with the mass percentage of the PS added increases, the thickness swelling after the thickness swelling after lithium rechargeable battery 4.4V/85 DEG C/24h stores and 4.4V/60 DEG C/15day store all has obvious reduction.
As can be seen from embodiment 38 with comparative example 10, embodiment 39 with comparative example 11, embodiment 40 with comparative example 12, embodiment 41 with comparative example 13, embodiment 42 with comparative example 14, embodiment 43 with comparative example 15, embodiment 44 with the contrast of comparative example 16, the lithium rechargeable battery adding the diisocyanate cpd of the ether-containing key with formula 1 structure in the electrolyte of lithium rechargeable battery than the lithium rechargeable battery only containing PS under high voltages (4.35V ~ 4.90V) there is better high-temperature storage performance.This may be the diisocyanate cpd of ether-containing key owing to having formula 1 structure can form one deck densification passivating film in pole piece, active material in prevention pole piece and the side reaction between electrolyte, reduce aerogenesis, so lithium rechargeable battery has lower thickness swelling; And the diisocyanate cpd with the ether-containing key of formula 1 structure can also react with the water in electrolyte, HF, reduce water, reaction between HF and electrolyte, reduce aerogenesis, lithium rechargeable battery also can be made to have lower thickness swelling.And the passivating film that independent PS is formed in pole piece is fine and close not and stable under high voltage condition, cause the high-temperature storage performance of lithium rechargeable battery poor.
(2) test result analysis of the cycle performance of lithium rechargeable battery
(any additive is not added from embodiment 1-17 and comparative example 1, capability retention after 25 DEG C of circulations is 20%, capability retention after 45 DEG C of circulations is 13%) contrast in can find out, the lithium rechargeable battery that with the addition of the diisocyanate cpd of the ether-containing key with formula 1 and/or formula 2 structure in the electrolyte of lithium rechargeable battery has capability retention after higher circulation.This is owing to not adding any additive in comparative example 1, and non-aqueous organic solvent in negative terminal surface, more side reaction can occur, and the capability retention after causing lithium rechargeable battery to circulate is lower.And the diisocyanate cpd with the ether-containing key of formula 1 and/or formula 2 structure can form the passivating film of one deck densification on positive plate surface, and there is high chemical reactivity due to the isocyanate functional group of the diisocyanate cpd of the ether-containing key with formula 1 and/or formula 2 structure, therefore it can biochemical reaction anti-with the functional group on negative plate surface, thus also form one deck passivating film on negative plate surface, active material in prevention pole piece and the side reaction between electrolyte, improve normal-temperature circulating performance and the high temperature cyclic performance of lithium rechargeable battery; And the passivating film formed by the diisocyanate cpd of the ether-containing key with formula 1 and/or formula 2 structure contains more oxygen atom, lithium ion can be reduced through resistance during passivating film, improve the interface performance between electrolyte and pole piece, thus improve normal-temperature circulating performance and the high temperature cyclic performance of lithium rechargeable battery.
As can be seen from the contrast of embodiment 1-7, the compound with molecular formula 1-2 structure of 0.1% ~ 2.5% is added in the electrolyte of lithium rechargeable battery, the passivating film of one deck densification can be formed in pole piece, active material in prevention pole piece and the side reaction between electrolyte, therefore lithium rechargeable battery has capability retention after higher circulation, and increase along with the mass percentage of the compound with molecular formula 1-2 structure, the capability retention after lithium rechargeable battery 25 DEG C and 45 DEG C circulate all first raises and omits reduction afterwards.But, when the mass percentage of the compound with molecular formula 1-2 structure is very few (comparative example 2), although normal-temperature circulating performance and the high temperature cyclic performance of lithium rechargeable battery can be improved, but also do not reach desirable effect, this may be the mass percentage of compound owing to having molecular formula 1-2 structure very little, the passivating film formed is fine and close not, effectively can not stop the side reaction between active material in pole piece and electrolyte, so the normal-temperature circulating performance of lithium rechargeable battery and high temperature cyclic performance poor.When the mass percentage of the compound with molecular formula 1-2 structure is too high (comparative example 3), 25 DEG C of lithium rechargeable battery and 45 DEG C circulation after capability retention all significantly reduce, this may be because the too much compound with molecular formula 1-2 structure causes the passivating film of formation blocked up, cause interface impedance larger, interface performance between pole piece and electrolyte is poor, and then the normal-temperature circulating performance of lithium rechargeable battery and high temperature cyclic performance worsen.
As can be seen from the contrast of embodiment 4 and embodiment 8-12, the diisocyanate cpd with the ether-containing key of formula 1 or formula 2 structure of 1% is added in the electrolyte of lithium rechargeable battery, owing to defining fine and close passivating film, prevent the side reaction between active material in pole piece and electrolyte, therefore lithium rechargeable battery has capability retention after higher circulation, capability retention after 25 DEG C of circulations is more than 80%, and the capability retention after 45 DEG C of circulations is more than 71%.
As can be seen from the contrast of embodiment 13-17, the mixture with the diisocyanate cpd of the ether-containing key of formula 1 and formula 2 structure of 1% is added in the electrolyte of lithium rechargeable battery, owing to defining fine and close passivating film, prevent the side reaction between active material in pole piece and electrolyte, therefore lithium rechargeable battery has capability retention after higher circulation, capability retention after 25 DEG C of circulations is more than 80%, and the capability retention after 45 DEG C of circulations is more than 72%.
It can also be seen that from the contrast of embodiment 8 and comparative example 4, the diisocyanate cpd with the ether-containing key of formula 1 structure adding 1% in the electrolyte of lithium rechargeable battery is better than the normal-temperature circulating performance of hexamethylene diisocyanate (HDI) and high temperature cyclic performance adding 1%.This passivating film that may be the diisocyanate cpd of ether-containing key owing to having formula 1 structure is formed contains more oxygen atom, lithium ion can be reduced through resistance during passivating film, show lower impedance, improve the interface performance between electrolyte and pole piece, thus improve normal-temperature circulating performance and the high temperature cyclic performance of lithium rechargeable battery.And the impedance of the passivating film formed by hexamethylene diisocyanate (HDI) is comparatively large, the interface performance between pole piece and electrolyte can be worsened, cause the normal-temperature circulating performance of lithium rechargeable battery and high temperature cyclic performance to worsen; And the deterioration of cycle performance at 25 DEG C is relatively more serious, this may be because at 25 DEG C, lithium ion is more difficult through passivating film, and lithium ion to be compared under 25 DEG C of conditions easily through passivating film at 45 DEG C.
(any additive is not added from embodiment 18-29 and comparative example 5, capability retention after 25 DEG C of circulations is 15%, capability retention after 45 DEG C of circulations is 10%) contrast in can find out, the lithium rechargeable battery adding the diisocyanate cpd of the ether-containing key with formula 1 or formula 2 structure in the electrolyte of lithium rechargeable battery has capability retention after higher circulation.This is owing to not adding any additive in comparative example 5, and non-aqueous organic solvent in negative terminal surface, more side reaction can occur, and the capability retention after causing lithium rechargeable battery to circulate is lower.And the diisocyanate cpd with the ether-containing key of formula 1 or formula 2 structure can form the passivating film of one deck densification on positive plate surface, and the isocyanate functional group with the diisocyanate cpd of the ether-containing key of formula 1 or formula 2 structure has high chemical reactivity, can biochemical reaction anti-with the functional group on negative plate surface, thus also can form one deck passivating film on negative plate surface, the active material in prevention pole piece and the side reaction between electrolyte; The passivating film that the diisocyanate cpd with the ether-containing key of formula 1 or formula 2 structure is formed can also stop the stripping of transition metal (Mn, Co, Ni etc.), thus improves normal-temperature circulating performance and the high temperature cyclic performance of lithium rechargeable battery; The passivating film that the diisocyanate cpd with the ether-containing key of formula 1 or formula 2 structure is formed contains more oxygen atom, lithium ion can be reduced through resistance during passivating film, show lower impedance, improve the interface performance between electrolyte and pole piece, thus improve normal-temperature circulating performance and the high temperature cyclic performance of lithium rechargeable battery.
As can be seen from the contrast of embodiment 18-24, the compound with molecular formula 1-2 structure of 0.1% ~ 2.5% is added in the electrolyte of lithium rechargeable battery, the passivating film of one deck densification can be formed in pole piece, active material in prevention pole piece and the side reaction between electrolyte, therefore lithium rechargeable battery has the capability retention after higher circulation, and increase along with the mass percentage of the compound with molecular formula 1-2 structure, small size reduction after the capability retention after lithium rechargeable battery 25 DEG C and 45 DEG C of circulations all first raises).But, when the mass percentage of the compound with molecular formula 1-2 structure is very few (comparative example 6), although normal-temperature circulating performance and the high temperature cyclic performance of lithium rechargeable battery can be improved, but also do not reach desirable effect, this may be the mass percentage of compound owing to having molecular formula 1-2 structure very little, cause formed passivating film fine and close not, effectively can not stop the side reaction between active material in pole piece and electrolyte, can not effectively stop transition metal (Mn, Co, Ni etc.) stripping, therefore the normal-temperature circulating performance of lithium rechargeable battery and high temperature cyclic performance do not reach desirable effect.When the mass percentage of the compound with molecular formula 1-2 structure is too high (comparative example 7), lithium rechargeable battery 25 DEG C and 45 DEG C circulation after capability retention all significantly reduce, this may be because the too much compound with molecular formula 1-2 structure causes the passivating film of formation blocked up, cause interface impedance comparatively large, cause the interface performance between pole piece and electrolyte poor; And the deterioration of cycle performance at 25 DEG C is relatively more serious, this may be because at 25 DEG C, lithium ion is more difficult through passivating film, and lithium ion to be compared under 25 DEG C of conditions easily through passivating film at 45 DEG C.
As can be seen from the contrast of embodiment 21 and embodiment 25-29, the diisocyanate cpd with the ether-containing key of formula 1 or formula 2 structure of 1% is added in the electrolyte of lithium rechargeable battery, owing to defining fine and close passivating film, prevent the side reaction between active material in pole piece and electrolyte, therefore lithium rechargeable battery has capability retention after higher circulation, capability retention after 25 DEG C of circulations is more than 84%, and the capability retention after 45 DEG C of circulations is more than 68%.
As can be seen from the contrast of embodiment 21 and comparative example 8, the lithium rechargeable battery with the diisocyanate cpd of the ether-containing key of formula 1 structure adding 1% in the electrolyte of lithium rechargeable battery is better than the normal-temperature circulating performance of lithium rechargeable battery of hexamethylene diisocyanate (HDI) and high temperature cyclic performance adding 1%.This passivating film that may be the diisocyanate cpd of ether-containing key owing to having formula 1 structure is formed contains more oxygen atom, lithium ion can be reduced through resistance during passivating film, show lower impedance, improve the interface performance between electrolyte and pole piece, thus improve normal-temperature circulating performance and the high temperature cyclic performance of lithium rechargeable battery.And the impedance of the passivating film formed by hexamethylene diisocyanate (HDI) is comparatively large, be degrading the interface performance between pole piece and electrolyte, cause the normal-temperature circulating performance of lithium rechargeable battery and high temperature cyclic performance to worsen; And the deterioration of cycle performance at 25 DEG C is relatively more serious, this may be because at 25 DEG C, lithium ion is more difficult through passivating film, and lithium ion to be compared under 25 DEG C of conditions easily through passivating film at 45 DEG C.
As can be seen from embodiment 30 with embodiment 3, embodiment 31 with embodiment 4, embodiment 32 with embodiment 5, embodiment 33 with the contrast of embodiment 6, capability retention after 45 DEG C of circulations is in suitable level, and the result of the capability retention embodiment 30-33 of 25 DEG C of circulations is better than embodiment 3-6.This may be that its viscosity is lower owing to adding EMC in the electrolyte of embodiment 30-33, the favourable conduction with lithium ion.The passivating film formed by the diisocyanate cpd of the ether-containing key with formula 1 structure still has certain impedance, and replace full-bodied PC, EC and DEC by the EMC part that viscosity is lower, the conduction of lithium ion between electrolyte and pole piece interface can be improved, further reduction impedance, improves normal-temperature circulating performance and the high temperature cyclic performance of lithium rechargeable battery further.But at 45 DEG C, little at the impedance ratio 25 DEG C of the passivating film formed by the diisocyanate cpd of the ether-containing key with formula 1 structure, so it is little to replace PC, EC and DEC impact on the capability retention after 45 DEG C of circulations by EMC part.
As can be seen from the contrast of embodiment 3, embodiment 34-37 and comparative example 9, containing have formula 1 structure ether-containing key diisocyanate cpd lithium rechargeable battery electrolyte in add PS again, normal-temperature circulating performance and the high temperature cyclic performance of lithium rechargeable battery can be improved.The normal-temperature circulating performance of the lithium rechargeable battery containing independent PS and high temperature cyclic performance are all poor, but the basis of the passivating film that PS can be formed at the diisocyanate cpd by the ether-containing key with formula 1 structure forms the stable passivating film of one deck again, passivating film is made to become composite passivation film, this composite passivation film can make the interface between pole piece and electrolyte more stable, and then improves normal-temperature circulating performance and the high temperature cyclic performance of lithium rechargeable battery.It can also be seen that from embodiment 34-37 contrast, along with the increase of the PS content added, the capability retention after 25 DEG C of lithium rechargeable battery and 45 DEG C of circulations all first increases and reduces afterwards, and normal-temperature circulating performance variation is more obvious.This may be due to too much PS used in combination with the diisocyanate cpd of ether-containing key with formula 1 structure time, cause the impedance of the composite passivation film formed larger, and the conduction of lithium ion is at normal temperatures responsive to impedance comparison, the increase of impedance is degrading the dynamic performance of lithium ion, is degrading the interface performance between pole piece and electrolyte simultaneously; And at 45 DEG C, the conduction ratio of lithium ion is easier to, the impact of increase on the dynamic performance of lithium ion of impedance is less, so also less on the impact of the capability retention after 45 DEG C of circulations.
As can be seen from embodiment 38 with comparative example 10, embodiment 39 with comparative example 11, embodiment 40 with comparative example 12, embodiment 41 with comparative example 13, embodiment 42 with comparative example 14, embodiment 43 with comparative example 15, embodiment 44 with the contrast of comparative example 16, the lithium rechargeable battery adding the diisocyanate cpd of the ether-containing key with formula 1 structure in the electrolyte of lithium rechargeable battery than the lithium rechargeable battery only containing PS under high voltages (4.35V ~ 4.90V) there is better normal-temperature circulating performance and high temperature cyclic performance.This may be the diisocyanate cpd of ether-containing key owing to having formula 1 structure can form one deck densification passivating film on positive plate surface, and the isocyanate functional group with the diisocyanate cpd of the ether-containing key of formula 1 structure has high chemical reactivity, can biochemical reaction anti-with the functional group on negative plate surface, thus also can form one deck passivating film on negative plate surface, active material in prevention pole piece and the side reaction between electrolyte, thus improve normal-temperature circulating performance and the high temperature cyclic performance of lithium rechargeable battery; And the passivating film formed by the diisocyanate cpd of the ether-containing key with formula 1 structure contains more oxygen atom, lithium ion can be reduced through resistance during passivating film, show lower impedance, improve the interface performance between electrolyte and pole piece, thus improve normal-temperature circulating performance and the high temperature cyclic performance of lithium rechargeable battery.And the passivating film that independent PS is formed in pole piece is fine and close not and stable in high voltage condition, therefore the normal-temperature circulating performance of lithium rechargeable battery and high temperature cyclic performance poor.
To sum up, the lithium rechargeable battery of diisocyanate cpd of the ether-containing key containing having formula 1 and/or formula 2 structure of the present invention has good high-temperature storage performance, normal-temperature circulating performance and high temperature cyclic performance under high voltages.
Claims (10)
1. an electrolyte for lithium rechargeable battery, comprising:
Lithium salts;
Non-aqueous organic solvent; And
Additive;
It is characterized in that,
Described additive comprises the diisocyanate cpd of the ether-containing key with formula 1 and/or formula 2 structure; In formula 1, m, n, p are respectively the integer of 1 ~ 4; In formula 2, x, y are respectively the integer of 1 ~ 4;
The described mass percentage of diisocyanate cpd in the electrolyte of lithium rechargeable battery with the ether-containing key of formula 1 and/or formula 2 structure is 0.1% ~ 2.5%.
2. the electrolyte of lithium rechargeable battery according to claim 1, is characterized in that,
Described non-aqueous organic solvent comprises the combination of cyclic carbonate and linear carbonate;
Described cyclic carbonate is selected from least one in ethylene carbonate (EC), propene carbonate (PC) and butylene (BC);
Described linear carbonate is selected from least one in dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl ethyl carbonate (EMC), methyl propyl carbonate (MPC) and ethyl propyl carbonic acid ester (EPC).
3. the electrolyte of lithium rechargeable battery according to claim 1, is characterized in that, described in there is the ether-containing key of formula 1 structure diisocyanate cpd be selected from and there is molecular formula 1-1 structure at least one in the compound of molecular formula 1-20 structure,
4. the electrolyte of lithium rechargeable battery according to claim 1, is characterized in that, described in there is the ether-containing key of formula 2 structure diisocyanate cpd be selected from and there is molecular formula 2-1 structure at least one in the compound of molecular formula 2-6 structure,
5. the electrolyte of lithium rechargeable battery according to claim 1, is characterized in that, described in there is the ether-containing key of formula 1 and/or formula 2 structure the mass percentage of diisocyanate cpd in the electrolyte of lithium rechargeable battery be 0.2% ~ 2%.
6. the electrolyte of lithium rechargeable battery according to claim 1, is characterized in that, described additive also comprises PS (PS).
7. the electrolyte of lithium rechargeable battery according to claim 6, is characterized in that, the mass percentage of described PS (PS) in the electrolyte of lithium rechargeable battery is 0.1% ~ 5%.
8. a lithium rechargeable battery, comprising:
Positive plate, comprises plus plate current-collecting body and is arranged at the positive pole diaphragm containing positive active material on plus plate current-collecting body;
Negative plate, comprises negative current collector and is arranged at the cathode membrane containing negative electrode active material on negative current collector;
Barrier film, is interval between positive plate and negative plate; And
Electrolyte;
It is characterized in that,
Described electrolyte is the electrolyte of the lithium rechargeable battery according to any one of claim 1-7.
9. lithium rechargeable battery according to claim 8, is characterized in that, the charging of described lithium rechargeable battery by voltage be 4.35V ~ 4.9V.
10. lithium rechargeable battery according to claim 8, is characterized in that, described positive active material is selected from Li
xco
ym
1-ya
2, LiMn
zn
2-zo
4in at least one, wherein, 0.97≤x≤1.06,0≤y≤1,0≤z≤2, M is selected from least one in Ni, Fe, Mg, Al, Ti, V, Ge, Zr, Mn, Cr, A is selected from least one in O, F, S, P, and N is selected from least one in Co, Ni, Fe.
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