CN104733783A - Preparation method of lithium ion battery - Google Patents

Abstract

The present invention belongs to the technical field of lithium-ion batteries, and particularly relates to a method for preparing a lithium-ion battery, including the steps of electrode preparation, lithium-rich layer arrangement, liquid injection formation (forming SEI film), lithium embedding in the lithium-rich layer, and finished battery cell preparation. When the lithium-rich layer is prepared by the method, the lithium-rich material layer is lightly (compounding pressure is not greater than 0.5MPa) compounded on the anode surface when the lithium is rich, and the contact between the lithium-rich material layer and the electrode surface is minimized and avoided, thereby reducing and avoiding the lithium in the lithium-rich material layer after electrolyte infiltration to be embedded in the anode active material and forming an SEI film with poor structural performance consistency, so that the prepared battery cell has more excellent electrochemical performance.

Description

A kind of preparation method of lithium ion battery

technical field

The invention belongs to the technical field of lithium ion batteries, in particular to a preparation method of lithium ion batteries.

Background technique

Lithium-ion batteries have the advantages of high energy density, high voltage, low self-discharge and light weight, so they are widely used in various portable mobile electronic devices such as notebook computers, digital cameras, mobile phones, and MP3 players. With the miniaturization and multi-function development of portable mobile electronic devices, people have higher and higher requirements on the energy density of lithium-ion secondary batteries. During the formation process of lithium-ion batteries, a solid electrolyte (SEI) film needs to be formed, which consumes Li ⁺ provided by the cathode, resulting in a loss of battery capacity and affecting the improvement of energy density. For the graphite system, the first conversion will bring about 10% energy loss; for some high-capacity alloy anode materials, such as silicon-based, tin-based and Sn-Co-Al composite materials, the first-time efficiency is even only 60%~ 80%, which has seriously affected the practical application and promotion of alloy materials.

In order to greatly increase the energy density of the cell, it is necessary to increase the first Coulombic efficiency of the cell. Therefore, experts at home and abroad have carried out extensive research and achieved some results: the patent of the Chinese patent application publication number CN1177417A uses metal lithium sheets to cover the surface of the anode sheet (using the entire sheet of foil as a current collector), and then winding A lithium-rich lithium-ion battery is prepared by forming a battery and then perfusing the electrolyte. When using this method to replenish lithium, since the existing process cannot produce thinner lithium metal sheets, the amount of lithium that the anode sheet can absorb is far less than the amount of lithium provided by the metal lithium sheet, resulting in excessive lithium replenishment and battery failure. Lithium analysis, poor cycle performance and other problems. The Chinese patent with the publication number CN103199217A proposes that the perforated metal lithium sheet is used to cover the surface of the anode sheet, then wound to form a battery, and then filled with an electrolyte to prepare a lithium-rich lithium-ion battery, which effectively solves the problem of being unable to produce The problem of thin enough lithium metal sheets.

However, the above-mentioned methods of improving the first-time efficiency of the battery through lithium-rich means, and then increasing the battery capacity, in the battery preparation process, after the liquid injection, with the infiltration of the electrolyte, ion channels and electrons are formed between the lithium-rich material and the lithium-rich electrode. When channeling, a solid electrolyte film (SEI film) will be spontaneously formed on the surface of the lithium-rich material particles. The film formation process of the SEI film is an uncontrollable process, and the formed SEI film has poor composition and structure consistency. Cycle performance is poor.

In view of this, it is necessary to develop a new lithium-ion battery and its preparation method, which can not only enrich the entire battery system with lithium, but also form an SEI film with good consistency in structure and performance, and finally prepare a battery with excellent performance. .

Contents of the invention

The object of the present invention is to provide a preparation method of lithium-ion battery in view of the deficiencies of the prior art: the method mainly includes electrode preparation, lithium-rich layer arrangement, liquid injection and chemical formation (formation of SEI film), lithium-rich layer embedding Lithium, finished battery cell preparation and other steps. Using this method to prepare lithium-ion batteries, when lithium is enriched, the lithium-rich material layer is lightly compounded (the composite pressure is not greater than 0.5MPa) on the surface of the anode, and the contact between the lithium-rich material layer and the electrode surface is minimized and avoided, thereby reducing, Avoid lithium intercalation in the anode active material in the lithium-rich material layer after the electrolyte is infiltrated and form an SEI film with poor consistency in structure and performance, so the prepared battery cell has more excellent electrochemical performance.

In order to achieve the above object, the present invention adopts the following technical solutions:

A preparation method for a lithium ion battery, comprising the steps of:

Step 1, preparation of the lithium-rich electrode: coating the slurry containing the anode active material on the current collector, and drying under cold pressure to obtain the lithium-rich electrode;

Step 2, preparation of batteries to be formed: lightly attach the lithium-rich substance to the surface of the electrode obtained in step 1, and form a layer of lithium-rich substance on the surface of the anode, the lithium-rich substance layer is a porous structure layer composed of lithium-rich substances, And the lithium-rich material layer forms as few electron channels as possible with the surface of the anode active material, and the pressure used when attaching is 0-0.5MPa; after that, it is assembled with the dried cathode sheet and separator to form a bare battery cell, which is put into the shell Inject liquid into the back of the bag and let stand;

Or: step 2, preparation of cells to be formed: the anode obtained in step 1, the dried cathode sheet (containing cathode active material), and the separator are assembled into a bare cell. A lithium-rich material layer is arranged between the film and the anode sheet, and at this time, the precise alignment between the two layers can be ensured under the small adhesive force between the anode and the lithium-rich material layer; then the bare cell is put into the case/bag After injection, let stand;

Step 3, Solid Electrolyte Membrane (SEI Membrane) Formation: Perform chemical conversion on the cells fully soaked with the electrolyte solution obtained in Step 2, the conversion temperature is 10°C-90°C, and the charging current is 0.01-5C (C is the battery capacity value, for example , if the battery capacity is 1500mAh, then 1C is the current of 1500mA), the pressure applied to the battery cell during formation is 0-0.5MPa, and the charging SOC (that is, the state of charge, 10% SOC is when the battery is charged to 10% of its capacity) state) is 3% to 90%;

Step 4, lithium intercalation: Apply a surface pressure of 0.5MPa to 5.0MPa to the cell obtained in step 3, so that the lithium-rich material layer is in full contact with the anode surface after the SEI film is formed (forms an electron channel). There is a potential difference between the anodes, and the lithium in the lithium-rich material layer will spontaneously embed into the anode active material layer, and finally achieve the effect of lithium supplementation;

Step 5, production of finished batteries: shaping and degassing the batteries prepared in step 4 to make finished batteries.

As an improvement of the preparation method of the lithium ion battery of the present invention, the anode sheet in step 1 is composed of an anode coating containing an anode active material and an anode current collector; the cathode sheet in step 2 is composed of a cathode coating containing a cathode active material and a current collector; the cathode coating or/and anode coating is a lithium-deficient layer; specifically, the anode active material includes carbon materials (graphite, disordered carbon), carbon-containing compounds (B～C～N series , C～Si～O series), non-carbon materials (metal oxides, lithium-transition metal nitrides, lithium alloys); the cathode active material includes lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium At least one of iron oxide, lithium vanadium oxide, ternary or multiple composite compound, sulfur or sulfide/sulfur composite cathode material and polyanion cathode material.

As an improvement to the preparation method of the lithium-ion battery of the present invention, the lithium-rich substance described in step 2 is a substance that can provide a lithium source for anode lithium supplementation, including lithium powder, lithium powder slurry, lithium tape, and perforated lithium tape , At least one of lithium-rich organic compounds (such as 1,4-butyl dilithium, 1,6-hexyl dilithium, etc.).

As an improvement of the preparation method of the lithium-ion battery of the present invention, the equivalent pore diameter of the porous structure layer composed of the lithium-rich substance described in step 2 (the equivalent pore diameter refers to when the pore area is converted into a circle area, the The diameter of the circle) is not more than 4cm; the width of the continuous lithium-rich layer between two holes (hole spacing) is not more than 4cm.

As an improvement of the preparation method of the lithium-ion battery of the present invention, the equivalent pore diameter of the porous structure layer composed of the lithium-rich substance described in step 2 is preferably no more than 2 cm; the width of the continuous lithium-rich layer between the two holes (pore spacing ) is preferably not more than 2 cm.

As an improvement of the preparation method of the lithium-ion battery of the present invention, the pressure used in step 2 of attachment is preferably 0-0.1 MPa.

As an improvement of the preparation method of the lithium-ion battery of the present invention, the attachment method described in step 2 is attached to one side of the anode to be enriched with lithium or attached to both sides of the anode to be enriched with lithium.

As an improvement to the preparation method of the lithium-ion battery of the present invention, the cell assembly method described in step 2 is winding or/and lamination; the bare cell is put into the shell with an aluminum shell or steel shell, and the bare cell into the bag is made of aluminum Plastic film or rust-free steel film; the liquid injection method is ordinary liquid injection or vacuum liquid injection; the static temperature is 10°C-100°C, and the time is 1min-72h.

As an improvement to the preparation method of the lithium-ion battery of the present invention, the formation temperature in step 3 is preferably 35°C-85°C, the charging current is preferably 0.01-1C, and the pressure applied to the cell during formation is preferably 0-0.1MPa , The charging SOC is 3% to 60%.

As an improvement to the preparation method of the lithium-ion battery of the present invention, the surface pressure applied to the cell in step 4 is preferably 0.5MPa-2.0MPa, the temperature is 20°C-100°C, and the time is 10min-48h.

Using this method to prepare lithium-ion batteries can effectively slow down/inhibit the lithium in the lithium-rich material layer from intercalating into the anode active material particles during the electrolyte infiltration process, and reduce/eliminate the formation of SEI films with poor consistency in the internal structure and performance of the anode (Because this kind of direct contact lithium intercalation process is an uncontrollable process); at the same time, through the controllable charge formation process, a SEI film with uniform structure and properties is formed on the surface of the fully wetted anode active material; when the SEI film passes through the controllable After the charging process is formed, pressure is applied to the battery cell, so that the lithium-rich material layer and the anode active material are in full contact to form electrons. Driven by the potential difference between the anode and the lithium-rich material layer, the lithium-rich material The lithium in the layer is spontaneously intercalated between the anode active materials; finally, a lithium-rich lithium-ion battery with high capacity and better cycle performance is obtained.

Detailed ways

The present invention and its beneficial effects will be described in detail below in conjunction with specific embodiments, but the embodiments of the present invention are not limited thereto.

Comparative example 1, preparation of lithium-rich bare cells: select silicon-carbon composites as the anode active material, stir with conductive agent, adhesive and deionized water to obtain a slurry, and then coat it on the copper current collector, cold press , slitting, welding, pasting and drying for later use; choose lithium cobaltate as the cathode active material and stir evenly with conductive agent, adhesive and nitrogen methyl pyrrolidone to obtain a slurry, and then apply it on the aluminum fluid, Drying after cold pressing, stripping, welding, and pasting glue for use; use metal lithium strips as the lithium-rich source, select the lithium strips according to the capacity relationship of the first full battery efficiency of 95%, and then use 2MPa surface pressure to compound the lithium strips The surface of the anode after drying; the above-mentioned cathode sheet and lithium-rich anode sheet are wound to obtain a bare cell.

Formation of SEI film: Encapsulate the above-mentioned bare cell in an aluminum-plastic film to obtain a top-sealed cell; according to EC:DEC:PC:VC:FEC=35:35:30:1:5 (VC and FEC are additives ), choose LiPF ₆ as the lithium salt to configure the electrolyte for backup; inject the above electrolyte into the above-mentioned top-sealed battery cell for vacuum packaging; place it in an environment of 35°C for 24 hours to fully infiltrate the electrolyte; The infiltration of the liquid, due to the voltage difference between the lithium-rich material attached to the surface of the anode and the anode active material, will automatically promote the generation of SEI on the surface of the anode active material particles;

Preparation of finished battery cells: Reshaping and degassing the above prepared battery cells to make finished battery cells.

Comparative example 2, preparation of lithium-rich bare cells: select silicon-carbon composites as the anode active material, stir evenly with conductive agent, adhesive and deionized water to obtain a slurry, and then coat it on the copper current collector, cold press , slitting, welding, pasting and drying for later use; choose lithium cobaltate as the cathode active material and stir evenly with conductive agent, adhesive and nitrogen methyl pyrrolidone to obtain a slurry, and then apply it on the aluminum fluid, Drying after cold pressing, slitting, welding, and gluing for use; the porous metal lithium strip is used as the lithium-rich source (the hole shape is circular, the hole diameter is 0.4cm, and the hole spacing is 1cm), and the first-time efficiency of the full battery is 95 According to the capacity relationship of %, the lithium strip is selected, and then the lithium strip is compounded on the surface of the dried anode with a surface pressure of 2 MPa; the above-mentioned cathode sheet and lithium-rich anode sheet are wound to obtain a bare cell.

Formation of SEI film: Encapsulate the above-mentioned bare cell in an aluminum-plastic film to obtain a top-sealed cell; according to EC:DEC:PC:VC:FEC=35:35:30:1:5 (VC and FEC are additives ), choose LiPF ₆ as the lithium salt to configure the electrolyte for backup; inject the above electrolyte into the above-mentioned top-sealed battery cell for vacuum packaging; place it in an environment of 35°C for 24 hours to fully infiltrate the electrolyte; The infiltration of the liquid, due to the voltage difference between the lithium-rich material attached to the surface of the anode and the anode active material, will automatically promote the generation of SEI on the surface of the anode active material particles;

Preparation of finished battery cells: Reshaping and degassing the above prepared battery cells to make finished battery cells.

Example 1, the preparation of the lithium-rich electrode: select the silicon-carbon composite as the anode active material, stir it with the conductive agent, the adhesive and the deionized water to obtain the slurry, and then coat it on the continuous copper current collector, cool After pressing, slitting, welding, and gluing, dry it for use;

Preparation of battery cells to be formed: choose lithium cobaltate as the cathode active material, stir with conductive agent, adhesive and nitrogen methyl pyrrolidone to obtain a slurry, and then apply it on the aluminum fluid, cold press, slitting, welding , dry after gluing and stand-by; the anode obtained above is wound into a bare cell with the cathode sheet and the separator, and in the assembly process of the bare cell, a lithium-rich material layer is arranged between the separator and the anode sheet (with The metal lithium strip is the lithium-rich source, and the thickness of the lithium strip is selected according to the capacity relationship of the first full battery efficiency of 95%. Precise alignment of cathode, anode, separator and lithium strip; then aluminum-plastic film is selected as the outer packaging material for packaging, liquid injection, and standing.

Formation of SEI film: chemically form the above-mentioned fully wetted cell at 45°C, apply a pressure of 0 MPa, charge current of 0.05C, and charge SOC of 30%, so that an SEI film is formed on the surface of the anode.

Lithium intercalation: Apply a surface pressure of 1.0 MPa to the above-mentioned cells with SEI film, and then place them in an environment of 45°C for 12 hours, so that a tight electronic channel is formed between the lithium ribbon and the anode sheet. At this time, the lithium ribbon and the anode sheet Under the action of the potential difference between the anodes, metal lithium will be automatically embedded in the anode sheet to supplement the anode with lithium.

Production of finished battery cells: shaping and degassing the above-mentioned battery cells to make finished battery cells.

Embodiment 2, different from Embodiment 1, this embodiment includes the following steps:

Preparation of lithium-rich electrode: same as Example 1.

Preparation of battery cells to be formed: choose lithium cobaltate as the cathode active material, stir with conductive agent, adhesive and nitrogen methyl pyrrolidone to obtain a slurry, and then apply it on the aluminum fluid, cold press, slitting, welding 1. After pasting the glue, dry it for use; choose the porous lithium strip as the lithium-rich source, the hole shape is circular, the hole diameter is 0.4cm, and the hole spacing is 1cm. Use 0.05MPa surface pressure to compound the porous lithium strip on the coating layer of the anode sheet Lithium anode composite electrodes are obtained on both sides, and then wound with cathode sheets and separators to form bare cells; after that, aluminum-plastic film is selected as the outer packaging material for packaging, liquid injection, and standing.

SEI film formation: chemically form the above-mentioned fully wetted cells at 70°C, apply a pressure of 0.05MPa, charge a current of 0.2C, and charge a SOC of 40%, so that an SEI film is formed on the surface of the anode.

Lithium intercalation: Apply a surface pressure of 0.8 MPa to the above-mentioned cells forming the SEI film, and then place them in an environment of 60°C for 8 hours, so that a tight electronic channel is formed between the lithium ribbon and the anode sheet. Under the action of the potential difference between the anodes, metal lithium will be automatically embedded in the anode sheet to supplement the anode with lithium.

The rest are the same as in Embodiment 1 and will not be repeated here.

Embodiment 3, different from Embodiment 2, this embodiment includes the following steps:

Preparation of lithium-rich electrode: same as Example 1.

Preparation of battery cells to be formed: choose lithium cobaltate as the cathode active material, stir with conductive agent, adhesive and nitrogen methyl pyrrolidone to obtain a slurry, and then apply it on the aluminum fluid, cold press, slitting, welding , After pasting the glue, dry it for use; choose the porous lithium strip as the lithium-rich source. The lithium anode composite electrode is obtained from the side, and then wound with the cathode sheet and the separator to form a bare cell; after that, the aluminum-plastic film is selected as the outer packaging material for packaging, liquid injection, and standing.

SEI film formation: chemically form the above-mentioned fully wetted cells at 90°C, apply a pressure of 0.5MPa, charge a current of 5C, and charge a SOC of 60%, so that an SEI film is formed on the surface of the anode.

Lithium intercalation: Apply a surface pressure of 5 MPa to the above-mentioned cells forming the SEI film, and then place them in an environment of 100°C for 1 hour, so that a tight electronic channel is formed between the lithium ribbon and the anode sheet. At this time, the lithium ribbon and the anode sheet Under the action of the potential difference between them, metal lithium will be automatically embedded in the anode sheet to supplement the anode with lithium.

The rest are the same as in Embodiment 2 and will not be repeated here.

Embodiment 4 is different from Embodiment 2 in that this embodiment includes the following steps:

Preparation of lithium-rich electrode: same as Example 1.

Preparation of battery cells to be formed: choose lithium cobaltate as the cathode active material, stir with conductive agent, adhesive and nitrogen methyl pyrrolidone to obtain a slurry, and then apply it on the aluminum fluid, cold press, slitting, welding , After pasting the glue, dry it for use; choose the porous lithium strip as the lithium-rich source, the hole shape is circular, the hole diameter is 2cm, and the hole spacing is 2cm. The lithium anode composite electrode is obtained from the side, and then wound with the cathode sheet and the separator to form a bare cell; after that, the aluminum-plastic film is selected as the outer packaging material for packaging, liquid injection, and standing.

SEI film formation: chemically form the above-mentioned fully wetted cells at 85°C, apply a pressure of 0.1MPa, charge a current of 1C, and charge a SOC of 50%, so that an SEI film is formed on the surface of the anode.

Lithium intercalation: Apply a surface pressure of 2 MPa to the above-mentioned cells forming the SEI film, and then place them in an environment of 70°C for 4 hours, so that a tight electronic channel is formed between the lithium ribbon and the anode sheet. At this time, the lithium ribbon and the anode sheet Under the action of the potential difference between them, metal lithium will be automatically embedded in the anode sheet to supplement the anode with lithium.

The rest are the same as in Embodiment 2 and will not be repeated here.

Embodiment 5, different from Embodiment 2, this embodiment includes the following steps:

Preparation of lithium-rich electrode: same as Example 1.

Preparation of battery cells to be formed: choose lithium cobaltate as the cathode active material, stir with conductive agent, adhesive and nitrogen methyl pyrrolidone to obtain a slurry, and then apply it on the aluminum fluid, cold press, slitting, welding , After pasting the glue, dry it for use; choose the porous lithium strip as the lithium-rich source, the hole shape is square, the equivalent hole diameter is 0.9cm, the hole spacing is 1.6cm, and the porous lithium strip is coated on the anode sheet with a surface pressure of 0.07MPa Lithium anode composite electrodes are obtained on both sides of the cladding layer, and then wound with cathode sheets and separators to form bare cells; then aluminum-plastic film is selected as the outer packaging material for packaging, liquid injection, and standing.

SEI film formation: chemically form the above-mentioned fully wetted cells at 70°C, apply a pressure of 0.07MPa, charge a current of 0.5C, and charge a SOC of 40%, so that an SEI film is formed on the surface of the anode.

Lithium intercalation: Apply a surface pressure of 1 MPa to the above-mentioned cells forming the SEI film, and then place them in an environment of 20°C for 48 hours, so that a tight electronic channel is formed between the lithium ribbon and the anode sheet. At this time, the lithium ribbon and the anode sheet Under the action of the potential difference between them, metal lithium will be automatically embedded in the anode sheet to supplement the anode with lithium.

The rest are the same as in Embodiment 2 and will not be repeated here.

Embodiment 6, different from Embodiment 2, this embodiment includes the following steps:

Preparation of lithium-rich electrode: same as Example 1.

Preparation of battery cells to be formed: choose lithium cobaltate as the cathode active material, stir with conductive agent, adhesive and nitrogen methyl pyrrolidone to obtain a slurry, and then apply it on the aluminum fluid, cold press, slitting, welding , After sticking the glue, dry it for use; choose the porous lithium strip as the lithium-rich source, the hole shape is triangular, the equivalent hole diameter is 0.1cm, the hole spacing is 0.5cm, and the porous lithium strip is coated on the anode sheet with a surface pressure of 0.02MPa Lithium anode composite electrodes are obtained on both sides of the cladding layer, and then wound with cathode sheets and separators to form bare cells; then aluminum-plastic film is selected as the outer packaging material for packaging, liquid injection, and standing.

SEI film formation: chemically form the above-mentioned fully wetted cells at 10°C, apply a pressure of 0.04MPa, charge a current of 0.01C, and charge a SOC of 40%, so that an SEI film is formed on the surface of the anode.

Lithium intercalation: Apply a surface pressure of 0.5MPa to the above-mentioned cells forming the SEI film, and then place them in a 40°C environment for 24 hours, so that a tight electronic channel is formed between the lithium ribbon and the anode sheet. At this time, the lithium ribbon and the anode sheet Under the action of the potential difference between the anodes, metal lithium will be automatically embedded in the anode sheet to supplement the anode with lithium.

The rest are the same as in Embodiment 2 and will not be repeated here.

Embodiment 7, different from Embodiment 2, this embodiment includes the following steps:

Preparation of lithium-rich electrodes: choose graphite as the anode active material, stir it with conductive agent, adhesive and deionized water to obtain a slurry, and then apply it on the porous copper current collector, cold press, slitting, welding, Dry after sticking.

Preparation of battery cells to be formed: choose lithium iron phosphate as the cathode active material, stir with conductive agent, adhesive and nitrogen methyl pyrrolidone to obtain a slurry, and then apply it on the aluminum fluid, cold press, slitting, welding 1. After pasting the glue, dry it for use; choose the porous lithium strip as the lithium-rich source, the hole shape is circular, the hole diameter is 0.4cm, and the hole spacing is 1cm. Use 0.05MPa surface pressure to compound the porous lithium strip on the coating layer of the anode sheet The lithium anode composite electrode is obtained on one side, and then wound with the cathode sheet and the separator to form a bare cell; after that, the aluminum-plastic film is selected as the outer packaging material for packaging, liquid injection, and standing.

SEI film formation: chemically form the above-mentioned fully wetted cells at 70°C, apply a pressure of 0.05MPa, charge a current of 0.2C, and charge a SOC of 90%, so that an SEI film is formed on the surface of the anode.

Lithium intercalation: Apply a surface pressure of 0.8 MPa to the above-mentioned cells forming the SEI film, and then place them in an environment of 60°C for 8 hours, so that a tight electronic channel is formed between the lithium ribbon and the anode sheet. Under the action of the potential difference between the anodes, metal lithium will be automatically embedded in the anode sheet to supplement the anode with lithium.

The rest are the same as in Embodiment 2 and will not be repeated here.

Embodiment 8, different from Embodiment 2, this embodiment includes the following steps:

Preparation of lithium-rich electrodes: choose graphite as the anode active material, stir it with conductive agent, adhesive and deionized water to obtain a slurry, and then apply it on the porous copper current collector, cold press, slitting, welding, Dry after sticking.

Preparation of battery cells to be formed: choose sulfur-carbon composite as the cathode active material, stir evenly with conductive agent, adhesive and nitrogen methyl pyrrolidone to obtain a slurry, and then apply it on the aluminum fluid, cold press, slitting, Welding and gluing, using the lithium strip lithium-rich technology to enrich the obtained sulfur cathode with lithium, and then use it; choose metal lithium powder as the lithium-rich source, and the particle size of the lithium powder is 50um; use 0.05MPa surface pressure to compound the lithium powder on the The lithium anode composite electrode is obtained on one side of the coating layer of the anode sheet, and then laminated with the cathode sheet and the separator to form a bare cell; after that, the aluminum-plastic film is selected as the outer packaging material for packaging, liquid injection, and standing.

SEI film formation: chemically form the above-mentioned fully wetted cells at 70°C, apply a pressure of 0.05MPa, charge a current of 0.2C, and charge a SOC of 90%, so that an SEI film is formed on the surface of the anode.

Lithium intercalation: Apply a surface pressure of 0.8 MPa to the above-mentioned cells forming the SEI film, and then place them in a 60°C environment for 8 hours, so that a tight electronic channel is formed between the lithium powder and the anode sheet. At this time, the lithium powder and the anode sheet Under the action of the potential difference between the anodes, metal lithium will be automatically embedded in the anode sheet to supplement the anode with lithium.

The rest are the same as in Embodiment 2 and will not be repeated here.

Characterization and Testing:

Capacity test: Take 100 batteries from Comparative Examples 1 and 2 and Examples 1 to 7 each, and conduct capacity tests on the batteries in an environment of 35°C according to the following procedure: stand for 3 minutes; 0.5C constant current Charge to 4.2V, constant voltage charge to 0.05C; stand still for 3min; discharge at 0.5C constant current to 3.0V to obtain the first discharge capacity D0; complete the capacity test after standing for 3min, and then calculate the capacity of 100 batteries in each group Average value, and calculate the Sigma of the capacity; the results obtained are shown in Table 1.

Take 100 batteries in Example 8, and test the capacity of the batteries according to the following procedure in an environment of 35°C: stand still for 3 minutes; charge at 0.5C constant current to 2.8V, and charge at constant voltage to 0.05C; C Discharge at a constant current to 1.5V to obtain the first discharge capacity D0; complete the capacity test after standing for 3 minutes, then calculate the average value of the capacity of 100 cells in each group, and calculate the Sigma of the capacity; the results are shown in Table 1.

Cycle test: For the cells in Comparative Examples 1 and 2 and Examples 1 to 7, take 5 cells each, and conduct a cycle test in an environment of 35°C. The process is: stand for 3 minutes; charge at 0.5C constant current to 4.2 V, charge at constant voltage to 0.05C; stand still for 3min; discharge at 0.5C constant current to 3.0V to obtain the first discharge capacity, and then calculate the average capacity of each group of 5 cells as D ₀ ; after standing for 3min, then cycle the above process The cell capacity was measured for 500 cycles, and then the average capacity of 5 cells in each group was calculated as D ₄₉₉ , then the cell capacity retention rate η=D ₄₉₉ /D ₀ *100%, the results are shown in Table 1.

Take 5 batteries in Example 8 and conduct a cycle test in an environment of 35°C. The process is: stand still for 3 minutes; charge at 0.5C constant current to 2.8V, and charge at constant voltage to 0.05C; stand still for 3 minutes; 0.5C constant current Discharge to 1.5V to get the first discharge capacity, then calculate the average capacity of each group of 5 cells as D ₀ ; after standing for 3 minutes, then repeat the above process for 500 weeks to measure the capacity of the cells, and then calculate the capacity of each group of 5 cells The average capacity is D ₄₉₉ , then the cell capacity retention rate η=D ₄₉₉ /D ₀ *100%, the results are shown in Table 1.

Table 1, the electrical performance table of the lithium-ion battery prepared by the method of comparative example and embodiment

According to Table 1, comparing Comparative Examples 1 and 2 with Examples 1 to 6, it can be obtained that when the lithium-ion battery is prepared by the method of the present invention, the obtained cell has a higher capacity, and the capacity distribution is more concentrated; in addition, the present invention The cycle performance of the battery cell prepared by the invention is better. It can be obtained from Examples 7 and 8 that the method is also applicable to the graphite/lithium iron phosphate system and the lithium-sulfur battery system, indicating that the method has universal applicability.

According to the disclosure and teaching of the above specification, those skilled in the art to which the present invention pertains can also change and modify the above embodiment. Therefore, the present invention is not limited to the above-mentioned specific implementation manners, and any obvious improvement, substitution or modification made by those skilled in the art on the basis of the present invention shall fall within the protection scope of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims (10)

1. a preparation method for lithium ion battery, is characterized in that, comprises the steps:

Step 1, treats the preparation of rich lithium anode: by the slurry coating containing anode active material in anode collector, colds pressing after drying and obtains treating rich lithium anode;

Step 2, battery core preparation to be changed: the surface for the treatment of rich lithium anode rich lithium material being attached to step 1 gained, to treat that rich lithium anode surface forms the rich lithium material layer of one deck, obtain rich lithium anode, described rich lithium material layer is the porous structure layer be made up of rich lithium material, and this rich lithium material layer is attached to anode active material surface, the pressure used during attachment is 0 ~ 0.5MPa; Afterwards rich lithium anode and the cathode sheets after drying, barrier film are assembled into naked battery core, after entering shell/bag, inject electrolyte, leave standstill;

Or be: step 2, the preparation of battery core to be changed: by step 1 gained until rich lithium anode with dry after cathode sheets, barrier film be assembled into naked battery core, in the assembling process of naked battery core, at barrier film and treat to arrange rich lithium material layer between rich lithium anode; Afterwards naked battery core is entered fluid injection after shell/bag, leave standstill;

Step 3, the generation of SEI film: change into the battery core fully infiltrated through electrolyte that step 2 obtains, changing into temperature is 10 DEG C ~ 90 DEG C, and charging current is 0.01 ~ 5C, be 0 ~ 0.5MPa to battery core applied pressure when changing into, charging SOC is 3% ~ 90%;

Step 4, embedding lithium: to the face pressure of battery core applying 0.5MPa ~ 5.0MPa that step 3 obtains, anode surface after making rich lithium material layer and forming SEI film fully contacts, to form electron channel, owing to there is electrical potential difference between rich lithium material layer and anode, lithium in rich lithium material layer embeds in spontaneous anode active material layer, and final realization mends lithium effect;

Step 5, the making of finished product battery core: the battery core that step 4 is obtained carries out shaping, degasification obtains finished product battery core.

2. a preparation method for lithium ion battery according to claim 1, is characterized in that, the cathode sheets described in step 2 is made up of the cathode containing cathode active material and collector; Described anode active material comprises at least one in material with carbon element, carbon compound and non-carbon material; Described cathode active material comprises at least one in lithium and cobalt oxides, lithium nickel oxide, lithium manganese oxide, oxide/lithium ferrite, lithium-barium oxide, ternary or multiple elements design compound, sulphur or sulfide/sulfur compound cathode material and polyanion cathode material.

3. the preparation method of a lithium ion battery according to claim 1, it is characterized in that, rich lithium material described in step 2, for mending for anode the material that lithium provides lithium source, comprises at least one in lithium powder, lithium powder slurry, lithium band, punching lithium band and rich lithium organic substance.

4. a preparation method for lithium ion battery according to claim 1, is characterized in that, the equivalent aperture diameter of the porous structure layer be made up of rich lithium material described in step 2 is no more than 4cm; Continuous rich lithium layer width between holes is no more than 4cm.

5. a preparation method for lithium ion battery according to claim 4, is characterized in that, the equivalent aperture diameter of the porous structure layer be made up of rich lithium material described in step 2 is for being no more than 2cm; Continuous rich lithium layer width between holes is no more than 2cm.

6. a preparation method for lithium ion battery according to claim 1, is characterized in that, the pressure used when adhering in step 2 is 0 ~ 0.1MPa.

7. a preparation method for lithium ion battery according to claim 1, is characterized in that, adhering mode described in step 2 is treating the one side attachment of rich lithium anode or treating the two-sided attachment of rich lithium anode.

8. a preparation method for lithium ion battery according to claim 1, is characterized in that, in step 2, naked battery core enters shell for entering aluminum hull or entering box hat, and naked battery core enters bag for entering aluminum plastic film bag or entering rustless steel membrane bag; Described fluid injection mode is normal pressure fluid injection or vacuum liquid filling; Described standing temperature is 10 DEG C ~ 100 DEG C, and leaving standstill the time continued is 1min ~ 72h.

9. a preparation method for lithium ion battery according to claim 1, is characterized in that, the temperature that changes into described in step 3 is 35 DEG C ~ 85 DEG C, and charging current is 0.01 ~ 1C, is 0 ~ 0.1MPa to battery core applied pressure when changing into, and charging SOC is 3% ~ 60%.

10. a preparation method for lithium ion battery according to claim 1, is characterized in that, the face pressure applied battery core described in step 4 is 0.5MPa ~ 2.0MPa, and temperature is 20 DEG C ~ 100 DEG C, and the time is 10min ~ 48h.