Lithium ion battery composite carbon negative polar material and preparation method thereof
Technical field
The present invention relates to a kind of negative material of lithium ion battery, especially relate to a kind of lithium ion battery composite carbon negative polar material and preparation method thereof.
Background technology
Lithium ion battery has characteristics such as high voltage, high-energy-density, long-life, memory-less effect, self discharge be little, has been widely used in various portable type electronic products, and in fields such as hybrid vehicle and pure electric automobiles potential application market has been arranged.Current, business-like lithium ion battery generally adopts graphite-like raw material of wood-charcoal material as negative material, though it has material specific capacity height, relative embedding lithium current potential than characteristics such as height, but the rapid charge characteristic of lithium ion battery that is based on the carbon back negative material is poor, has influenced the extensive application of lithium ion battery in short charging market.Therefore, seek to satisfy the negative material that quick charge uses is the hope of industry always.Why the carbon back negative material can not be used for quick charge, its main cause is because the compatibility and the high magnification charging performance of graphite mould class material with carbon element and electrolyte solution are relatively poor, in order to guarantee the cyclical stability preferably of carbon back negative material, just must on carbon negative pole material, form the stable solid-phase electrolyte film of one deck (Solid Electrolytes Interface, SEI), and the SEI film is slower in the forming process of first charge-discharge cyclic process usually, and in the charge and discharge cycles process, can change, thereby make intergranular electric conductivity variation, influence its chemical property.Therefore, material with carbon element is carried out modification improve its chemical property, particularly the large current charge performance seems particularly important.Normally the method that adopts the surface to coat the amorphous carbon material is improved high rate during charging-discharging ([1] Masaki Yoshio of graphite-like negative material, et al.Carbon-coated natural graphite prepared by thermal vapor decomposition process, a candidate anode material for lithium-ion battery.Journal of Power Sources, 93 (2001) 123-129; [2] Y.F.Zhou, et al.Pyrolytic polyurea encapsulated natural graphite as anode material for lithium ion batteries.Electrochimica Acta 50 (2005) 4728-4735), to fill the degree of performance soon limited but improve battery material, and the current potential terminal point of its indication is also not obvious.The chemical property that has research to be reported in carbon surface metal lining (for example silver, copper, Kufil) in recent years can to improve material with carbon element (people such as [3] Zhou Xiangyang. the chemical silvering crystalline flake graphite is made lithium ion battery negative material. battery, 32 (2002) 255-257; [4] people such as Cheng Xiaoai. graphite surface metalized and detection. sufacing, 35 (2006) 4-7), the result shows, after graphite surface coats layer of metal, not only resistivity reduces, and has improved the variation of electrode graphite volume in charge and discharge process, has reduced the electrode expansion, electrode thermal stability and cyclicity all obtain raising to a certain degree, but it still can't solve the problem of its quick charge.In addition, 2010, people's such as Liu Xingjiang (CN 101728524A) patent " a kind of lithium ion battery/capacitor electrode material and preparation method thereof " once proposed to cover the composite material that titanium oxide prepares tool at carbon surface, but this patent application only is in order to improve the conductivity of titanium oxide, and then the multiplying power discharging property of raising titanium oxide, than the titanium oxide material that carbon coats, because the electric conductivity difference of titanium oxide, the conductivity of this class sandwich does not have fine improvement.
Summary of the invention
The objective of the invention is to exist the shortcoming of high magnification charging performance difference at existing carbon negative pole material, pass through reasonable structural design, a kind of influence of the SEI of minimizing film anticathode material cyclical stability is provided, also can partly avoid simultaneously the influence to its cycle performance behind the negative material surface deposition of anodal dissolved metal ions, lithium ion battery composite carbon negative polar material and preparation method thereof of high-energy-density type still can be provided under big charging current condition.
Lithium ion battery of the present invention is provided with at least 3 layers nuclear shell structure with composite carbon negative polar material, and skin is metal level, alloy-layer or carbon-coating, and the intermediate layer is lithiumation metal oxide layer or metal oxide layer, and internal layer is the material with carbon element layer; By mass percentage, described material with carbon element is 85%~97%, and lithiumation metal oxide or metal oxide are 2.9%~15%, and metal, alloy or carbon are 0.1%~3%.
Described material with carbon element can be selected from a kind of in carbonaceous mesophase spherules (MCMB), graphite, activated carbon, the carbon fiber (VGCF) etc., and the scale size of described material with carbon element is micron or sub-micron.
The lithiumation metal oxide or the metal oxide in described intermediate layer can be selected from the metal oxide with spinel structure, or pure metal oxides, or lithiumation nonmetal oxide and metal oxide etc., described metal can be selected from Ti, Al, Zr, Zn, Nb, Mo, W or their alloy etc., the described nonmetal Si that is selected from, P, Ge, S, Cl etc.; Described outer field thickness can be 1~300nm.
Described lithium ion battery may further comprise the steps with the preparation method of composite carbon negative polar material:
1) raw material that will prepare metal oxide mixes the back drying with material with carbon element;
2), obtain having the lithiumation metal oxide of nucleocapsid structure or the composite material of metal oxide layer and material with carbon element with the heat-agglomerating under atmosphere protection of dried raw material;
3) on the composite material surface plating, have metal, alloy or the carbonaceous conductive layer of reversible machine ductility, make the lithium ion battery composite carbon negative polar material.
In step 1), described drying can adopt spray drying, oven drying or infra-red drying etc.
In step 2) in, the temperature of described heat-agglomerating can be 400~900 ℃, and the time of described heat-agglomerating can be 3~24h;
Described lithiumation metal oxide is a lithium titanate, can adopt solid reaction process and liquid phase sol-gal process to obtain lithium titanate, and the raw material of preparation lithium titanate is lithium carbonate and titanium dioxide, lithium hydroxide and titanium dioxide in the solid phase method.Sol gel precursor is butyl titanate/lithium hydroxide or lithium acetate/absolute ethyl alcohol/glacial acetic acid/water, butyl titanate/lithium acetate/isopropyl alcohol/acetic acid/water, isopropyl titanate/lithium acetate/ethanol, isopropyl titanate or titanium butoxide/absolute ethyl alcohol/lithium metal, drying means is spray drying, oven drying, infra-red drying, and temperature is that 750~900 ℃, time are 16~24h;
Described metal oxide layer is a titanium dioxide, and the raw material of preparation titanium dioxide is a butyl titanate, and drying means is oven drying, infra-red drying, and temperature is 400~500 ℃, and the time is 3~8h;
Described metal oxide layer is an aluminium oxide, and the raw material of preparation aluminium oxide is an aluminum nitrate, and drying means is oven drying, infra-red drying, and temperature is 400~500 ℃, and the time is 3~5h.
In step 3), the method for described plating can be chemical plating, plating, magnetron sputtering, ion/electron beam transpiration or thermal decomposition etc.
Compare with negative material with existing lithium ion battery, the present invention has following outstanding advantage:
Adopt multi-layer compound structure of the present invention as lithium ion battery negative material, have following characteristics: lithiumation metal oxide or metal oxide layer and metal or alloy layer can completely cut off material with carbon element effectively and contact with the direct of electrolyte, suppressed the growth of SEI film under high power charging-discharging or Li formation effectively, improved the chemical property of C-base composte material at electrode surface; Simultaneously intermediate layer otide containing lighium thing for example lithium titanate as the active material of embedding lithium, have very high ionic conductivity and almost do not have volumetric expansion and have good high rate performance; Outermost metal, alloy or carbon coating layer improve intergranular contact electricity effectively and lead whole electronic conductance with material.Therefore, multi-layer compound structure negative material of the present invention can be worked under big electric current, shows high-rate charge-discharge capability preferably, also helps realizing good high rate performance.Simultaneously, because raw material cheapness of the present invention, technology is simple, processing ease, and therefore multilayer materials of the present invention has high cost performance and market potential preferably.With MCMB/LTO/Cu sandwich construction composite material is example, at 75mAg
-1Reversible capability of charging and discharging reaches 300mAhg under the current density
-1At 372mAg
-1Reversible capability of charging and discharging remains on 215mAhg under the current density
-1, embodied high rate performance preferably.
The present invention makes each nuclear, shell brings into play function separately respectively, and then sandwich is reached be applicable to the characteristics of quick charge, height ratio capacity and long circulation life thereof.The negative material of this multi-layer compound structure is characterized in having the metal of multi-layer core-shell structure or the compound of alloy, lithiumation metal oxide or metal oxide layer and material with carbon element.
Description of drawings
Fig. 1 is that lithium ion battery of the present invention is formed schematic diagram with the structure of composite carbon negative polar material embodiment.
Fig. 2 is the sem photograph of MCMB/LTO/Cu sandwich construction composite sample among the embodiment 6.In Fig. 2, scale is: μ m a.5.00, b.500nm.
Fig. 3 is the x-ray diffraction pattern of MCMB/LTO/Cu sandwich construction composite sample among the embodiment 6.In Fig. 3, abscissa is angle of diffraction 2-Theta/degree, and ordinate is diffracted intensity Intensity/a.u..
Fig. 4 is the first charge-discharge curve of battery among the embodiment 11.In Fig. 4, abscissa is Specific capacity/mAhg
-1, ordinate is Voltage/V, current density: a 74mAg
-1B 186mAg
-1C 372mAg
-1
Fig. 5 is the cycle performance of battery among the embodiment 11.In Fig. 5, abscissa is Cycle number, and ordinate is Specific capacity/mAhg
-1Current density: 0.2C=74mAg
-10.5C=186mAg
-11C=372mAg
-1■ is 1C, ● be 0.5C, ▲ be 0.2C.
Fig. 6 is the cycle performance of battery among the embodiment 11.In Fig. 6, abscissa is Cycle number, and left side ordinate is Specific capacity/mAhg
-1, the right ordinate is efficiency/%; Current density is 1116mAg
-1, voltage is 2.5~0.005V; ■ is discharge, ● be charge, ▲ be efficiency/%.
Fig. 7 is the cyclic curve under the various multiplying powers of battery among the embodiment 11.In Fig. 7, abscissa is Cycle number, and left side ordinate is Specific capacity/mAhg
-1, the right ordinate is efficiency/%; Current density is 0.2C=74mAg
-10.5C=186mAg
-11C=372mAg
-13C=1116mAg
-15C=1860mAg
-1■ is charge, ● be discharge, ▲ be efficiency/%.
Fig. 8 is the CV curve of battery among the embodiment 11.In Fig. 8, abscissa is Potential/V, and ordinate is Current/mA, and sweep speed is 0.2mV/s; A is 1st, and b is 2nd, and c is 3th.
Fig. 9 is the first charge-discharge curve of battery among the embodiment 12.In Fig. 9, abscissa is Specific capacity/mAhg
-1, ordinate is Voltage/V; Current density is: a 74mAg
-1B 186mAg
-1C 372mAg
-1D 1116mAg
-1
Figure 10 is for implementing the cyclic curve under the various multiplying powers of battery in 12.In Figure 10, abscissa is Cycle number, and left side ordinate is Specific capacity/mAhg
-1, the right ordinate is efficiency/%, current density: 0.2C=74mAg
-10.5C=186mAg
-11C=372mAg
-13C=1116mAg
-15C=1860mAg
-1■ is discharge, ● be charge, ▲ be efficiency/%.
Figure 11 is for implementing the cycle performance of battery in 12.In Figure 11, abscissa is Cycle number, and left side ordinate is Specific capacity/mAhg
-1, the right ordinate is efficiency/%; Current density is 1116mAg
-1■ is discharge, ● be charge, ▲ be efficiency/%.
Embodiment
The preparation of embodiment 1MCMB/LTO composite material of core-shell structure sol-gal process
Butyl titanate and MCMB are joined in an amount of absolute ethyl alcohol in proportion as A liquid, and lithium acetate adds in the absolute ethyl alcohol, adds a certain amount of deionized water and glacial acetic acid as B liquid, B liquid is joined in the A liquid, at 50 ℃ of water-baths heating, magnetic agitation 3h.The material that mixes is carried out spray drying.Dry back material is put into nitrogen atmosphere protection stove, heats 24h down at 800 ℃, makes the MCMB/LTO composite material with nucleocapsid structure.
The preparation of embodiment 2MCMB/LTO composite material of core-shell structure solid sintering technology
By stoichiometric proportion mixed carbonic acid lithium and anatase-type nanometer titanium dioxide, add a certain proportion of MCMB and proper amount of acetone solvent, ball milling mixing 3h, rotating speed are 300r/min.With the 80 ℃ of vacuumize 2h of material that mix, put into nitrogen atmosphere protection stove, heat 24h down at 800 ℃, make MCMB/LTO composite material with nucleocapsid structure.
Embodiment 3MCMB/TiO
2The preparation of composite material of core-shell structure
Butyl titanate and MCMB are mixed in proportion, and ball milling 3h, rotating speed are 300r/min.Material magnetic agitation drying in air with mixing moves to 60 ℃ of dry 24h in the baking oven.Dry back material is put into nitrogen atmosphere protection stove, at 450 ℃ of following sintering 5h, makes the MCMB/TiO with nucleocapsid structure
2Composite material.
The preparation of embodiment 4MCMB/LTO composite material of core-shell structure two-step method
Mix with lithium carbonate by the MCMB/TiO2 composite material of core-shell structure among the embodiment 3 of stoichiometric proportion, add the proper amount of acetone solvent, ball milling mixing 3h, rotating speed are 300r/min.With the 80 ℃ of vacuumize 2h of material that mix, put into nitrogen atmosphere protection stove, heat 24h down at 800 ℃, make MCMB/LTO composite material with nucleocapsid structure.
Embodiment 5MCMB/Al
2O
3The preparation of composite material of core-shell structure
By stoichiometric proportion mixed nitrate aluminium and MCMB, be solvent with the proper amount of acetone, ball milling mixing 3h, rotating speed are 300r/min.With the 80 ℃ of vacuumize 2h of material that mix, put into nitrogen atmosphere protection stove, heat 4h down at 500 ℃, make MCMB/Al with nucleocapsid structure
2O
3Composite material.
The preparation of embodiment 6MCMB/LTO/Cu sandwich construction composite material
The MCMB/LTO composite material of core-shell structure that embodiment 1 is obtained carries out sensitization, activation, reduction processing.Sensitization technology is: SnCl
220g/L, HCl 2ml/L, the temperature room temperature stirs 10min, and is extremely neutral with distilled water flushing at last; Activating process is: PdCl
20.5g/L HCl 10ml/L boils and stirs 10min down, and is extremely neutral with distilled water flushing at last; Reducing process: NaH
2PO
2H
2O 40g/L, the temperature room temperature stirs 10min, and is extremely neutral with distilled water flushing at last.The sample of handling well is put into plating bath, and the chemical plating process of selecting for use is: CuSO
45H
2O 12g/L, EDTA disodium salt 40g/L, formaldehyde (37%) 6ml/L, NaOH 20g/L, α-α ' bipyridine 100mg/L, pH value 13.5,25~40 ℃ of temperature stir 10min.Material after the copper facing is obtained MCMB/LTO/Cu sandwich construction composite material with the distilled water flushing drying.
Embodiment 7
The MCMB/LTO composite material of core-shell structure that embodiment 2 is obtained carries out the electroless copper processing by the method for embodiment 6, obtains MCMB/LTO/Cu sandwich construction composite material.
Embodiment 8
The MCMB/TiO that embodiment 3 is obtained
2Composite material of core-shell structure carries out electroless copper by the method for embodiment 6 to be handled, and obtains MCMB/TiO
2/ Cu sandwich construction composite material.
Embodiment 9
The MCMB/LTO composite material of core-shell structure that embodiment 4 is obtained carries out the electroless copper processing by the method for embodiment 6, obtains MCMB/LTO/Cu sandwich construction composite material.
Embodiment 10
The MCMB/Al that embodiment 5 is obtained
2O
3Composite material of core-shell structure carries out electroless copper by the method for embodiment 6 to be handled, and obtains MCMB/Al
2O
3/ Cu sandwich construction composite material.
Embodiment 11
The material preparation that embodiment 6 is obtained becomes negative pole, presses composite material: acetylene black: binding agent=85: 5: 10 (mass ratio), and the ball milling mixing is coated on the Copper Foil of handling, and in 120 ℃ of oven dry, compression moulding under 20MPa obtains the chargeable lithium battery negative pole.With negative pole, Cellgard 2400 barrier films and the lithium sheet CR2025 button cell of packing in order, 1molL
-1LiPF
6EC/DMC solution be electrolyte, seal the back and on LAND battery test system (Wuhan blue electric Electronics Co., Ltd.), carry out the constant current charge-discharge performance test and carry out the cyclic voltammetric test at CHI608A electrochemical analyser (Shanghai occasion China instrument company).Voltage range: 2.5-0.005V, current density is respectively 74mAg
-1, 186mAg
-1, 372mAg
-1, 1116mAg
-11860mAg
-1Sweep speed is 0.2mV/s.Test environment: 25 ℃ of constant temperature.Test result is shown in Fig. 4~8.
Embodiment 12
The MCMB material preparation is become negative pole, press material: acetylene black: binding agent=85: 5: 10 (mass ratio), the ball milling mixing is coated on the Copper Foil of handling, and in 120 ℃ of oven dry, compression moulding under 20MPa obtains the chargeable lithium battery negative pole.With negative pole, Cellgard 2400 barrier films and the lithium sheet CR2025 button cell of packing in order, 1molL
-1LiPF
6EC/DMC solution be electrolyte, seal the back and on LAND battery test system (Wuhan blue electric Electronics Co., Ltd.), carry out the constant current charge-discharge performance test and carry out the cyclic voltammetric test at CHI608A electrochemical analyser (Shanghai occasion China instrument company).Voltage range: 2.5~0.005V, current density is respectively 74mAg
-1, 186mAg
-1, 372mAg
-1, 1116mAg
-11860mAg
-1Test environment: 25 ℃ of constant temperature.Test result is shown in Fig. 9~11.