CN101414693A - Energy storage battery based on lithium ion conduction and preparation method (thereof) - Google Patents

Abstract

The present invention proposes an energy storage battery based on lithium ion conduction, which is different from the traditional lithium ion battery system in that it is characterized in that lithium titanate (Li ₄ Ti ₅ O ₁₂ ) with a spinel structure replaces the layered structure Graphite (C ₆ ) is used as the negative electrode active material, lithium manganese oxide (LiMn ₂ O ₄ ) with spinel structure or lithium iron phosphate (LiFePO ₄ ) with olivine structure replaces lithium cobalt oxide (LiCoO ₂ ) with layered structure as a positive electrode active material. Main negative electrode active material or positive main active material, mixed with carbon black and binder, coated on aluminum foil to make positive and negative electrode sheets, and then energy storage battery. Li ₄ Ti ₅ O ₁₂ /LiMn ₂ O ₄ (or LiFePO ₄ ) system lithium-ion battery has higher energy density, excellent cycle performance, good safety performance and high-efficiency rate performance compared with traditional lithium-ion battery system , very suitable for the requirements of large energy storage batteries.

Description

An energy storage battery based on lithium ion conduction and its manufacturing method

technical field

The invention belongs to the technical field of electrochemistry, and specifically relates to a high-performance lithium-ion energy storage battery based on lithium-ion conduction and a manufacturing method thereof.

Background technique

With the increasing popularity of renewable energy, such as wind energy, solar energy, and fuel cells, and the urgent need for grid peak regulation, improving grid reliability, and improving power quality, the importance of power storage systems has become increasingly prominent. Large-capacity energy storage systems can also be used in residential quarters, hospitals, large enterprises, military, etc. as emergency power sources. Therefore, the application prospect of electric energy storage technology is very broad.

Current energy storage methods can be divided into chemical energy storage and physical energy storage. Among them, chemical energy storage methods mainly include lead-acid batteries, redox flow batteries, sodium-sulfur batteries, supercapacitors, nickel-metal hydride batteries, and lithium-ion batteries. Physical energy storage methods mainly include pumped water storage, compressed air energy storage, flywheel energy storage and superconducting energy storage. From the perspective of development level and practicality, chemical energy storage methods have broader development prospects than physical energy storage methods. Among the energy storage batteries currently in commercial operation, lead-acid batteries are the oldest and most mature energy storage method, which are cheap and reliable. However, due to deep discharge, the battery loss is very large, the cycle life is short, especially at high temperature, the energy and power density are also very low, and daily maintenance is more frequent. The sodium-sulfur battery has an energy density three times that of a lead-acid battery, has good high-current discharge performance, and high energy efficiency (up to 80%). However, the working temperature of the sodium-sulfur battery is 300-350°C, and heating and heat preservation measures are required. At the same time, the sodium-sulfur battery cannot be overcharged or over-discharged, and the charging and discharging state of the battery needs to be strictly controlled; and the ceramic diaphragm in the sodium-sulfur battery is quite fragile, and it is easily damaged when the battery is subjected to external force impact or mechanical stress, so the cycle life of the battery is limited. of. The energy efficiency of the redox flow battery is high, up to 70% to 80%, the stack is easy to expand, ultra-deep discharge does not cause irreversible damage to the battery, the construction period is short, and the system operation and maintenance costs are low. However, the power density of redox flow batteries is low, the temperature stability of electrode materials and diaphragm materials is poor, and electrolyte management is difficult.

Lithium-ion batteries, which came out in the early 1990s, have the advantages of high energy density, low self-discharge rate, high charge-discharge efficiency, long cycle life, and environmental friendliness, and are now widely used in various communications and electronic products. The working principle of conventional lithium-ion batteries is that lithium ions are intercalated back and forth between the lithium cobaltate positive electrode and the graphite negative electrode with a layered structure to realize the mutual conversion of electrical energy and chemical energy. However, the cost, service life and safety problems caused by the volume effect of graphite materials during charging and discharging, the deposition of metal lithium easily during overcharging, the high price of lithium cobaltate materials, and poor thermal stability restrict the use of lithium-ion batteries. Application of large energy storage devices. For this reason, the present invention will propose a kind of high-performance novel lithium-ion battery that replaces conventional positive and negative electrode materials as an energy storage device.

Contents of the invention

The object of the present invention is to propose a high-performance lithium ion energy storage battery, and the present invention is characterized in that lithium titanate (Li ₄ Ti ₅ O ₁₂ ) with a spinel structure is used to replace graphite (C ₆ ) with a layered structure as As the negative electrode active material, lithium manganese oxide (LiMn ₂ O ₄ ) with spinel structure or lithium ferrous phosphate (LiFePO ₄ ) with olivine structure replaces layered lithium cobalt oxide (LiCoO ₂ ) as the positive electrode active material.

Li ₄ Ti ₅ O ₁₂ has a three-dimensional lithium ion diffusion channel, and the lithium ion diffusion coefficient is 2×10 ^-8 cm ² /S, which is an order of magnitude higher than that of carbon anode materials; its skeleton remains unchanged during charging and discharging, and belongs to zero strain Materials; high charge and discharge platform (~1.5V), no deposition of metal lithium will occur. LiMn ₂ O ₄ has the characteristics of low price, fast diffusion of lithium ions, and good safety. LiFePO ₄ has the characteristics of low raw material cost, stable crystal structure, and good thermal stability.

The lithium ion energy storage battery composed of Li ₄ Ti ₅ O ₁₂ /LiMn ₂ O ₄ (or LiFePO ₄ ) system has high energy density, excellent cycle performance, good safety performance, high-efficiency rate performance and no Pollution and other characteristics, it is very suitable for large-scale energy storage batteries.

The manufacturing steps of the described energy storage battery based on lithium ion conduction are as follows:

(1) Production of battery pole pieces

The polyvinylidene chloride binder is added to an appropriate amount of N-methylpyrrolidone solvent (the mass of the solvent is 0.5 to 2 times the mass of the active material to be added), stirred and dissolved to form a glue solution. The active material (Li ₄ Ti ₅ O ₁₂ or LiMn ₂ O ₄ or LiFePO ₄ ) and carbon black are active material: carbon black: mass percentage of binder = 70-95%: 2-20%: 3-10% Add the proportion of the glue to the glue, stir and mix well, and then apply it on both sides of the aluminum foil (thickness 15-30μm). Constitute a positive or negative plate.

(2) Battery production

The battery pole pieces are vacuum dried, rolled and then cut to the required size. After the positive and negative plates are separated by a separator, they are wound or stacked into batteries. The required battery is obtained after the battery cell is packed, welded, liquid injected, sealed, formed and divided.

(3) Production of energy storage battery pack

Single batteries are sorted to form modules, and then the modules are assembled into battery packs according to energy storage requirements. After sorting, batteries with relatively consistent performance (sorting requirements: capacity deviation ±1.0%, internal resistance deviation ±0.3mΩ, charge-discharge platform deviation ±2mV, and self-discharge rate ±1.0%) are combined into modules. According to energy storage requirements, the battery modules are assembled into battery packs (such as 100Ah, 380V).

Description of drawings

Figure 1: The charge-discharge curve of the Li ₄ Ti ₅ O ₁₂ /LiMn ₂ O ₄ battery of Example 1 at room temperature at 1C rate.

Figure 2: 1C cycle curve of the Li ₄ Ti ₅ O ₁₂ /LiMn ₂ O ₄ battery of Example 1 at room temperature.

Figure 3: The charge-discharge curve of the Li ₄ Ti ₅ O ₁₂ /LiFePO ₄ battery of Example 2 at room temperature at 1C rate.

Detailed ways

Example 1

First, add polyvinylidene fluoride to an appropriate amount of N-methylpyrrolidone, stir and dissolve to make a glue solution for use. After mixing the negative electrode active material Li ₄ Ti ₅ O ₁₂ and carbon black, add it to the above glue (Li ₄ Ti ₅ O ₁₂ : superconducting carbon black: polyvinylidene fluoride mass percentage = 90:5:5), fully After stirring and mixing, it is evenly coated on both sides of aluminum foil (thickness: 20 μm) to make a negative electrode sheet. Similarly, mix the positive electrode active material LiMn ₂ O ₄ and carbon black and add it to the above glue (LiMn ₂ O ₄ : carbon black: polyvinylidene fluoride mass percentage = 92:5:3), stir and mix well, and evenly Coated on both sides of aluminum foil (thickness: 20 μm) to make a positive electrode sheet.

The positive and negative electrode sheets prepared above were dried under vacuum at 80° C. for 8 hours, then rolled and cut. After the cut positive and negative electrodes are separated by a separator, they are wound into batteries. After the battery core is loaded into the cylindrical steel shell, it is welded at the bottom, roller groove, and injected (the electrolyte is ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate of 1M lithium hexafluorophosphate, of which ethylene carbonate, dimethyl carbonate , The volume ratio of ethyl methyl carbonate is 1:1:1), and it is made into a cylindrical battery after sealing.

It can be seen from Figure 1 that the 1C discharge platform of the Li ₄ Ti ₅ O ₁₂ /LiMn ₂ O ₄ battery is 2.2V, which is lower than that of the traditional LiCoO ₂ /C lithium-ion battery (~3.6V). It can be seen from Figure 2 that the Li ₄ Ti ₅ O ₁₂ /LiMn ₂ O ₄ battery still maintains about 90% of its capacity after 2000 cycles, while the traditional LiCoO ₂ /C battery usually has a cycle life of <500 cycles, which does not meet the storage requirements. battery life requirements. The cycle performance of Li ₄ Ti ₅ O ₁₂ /LiMn ₂ O ₄ batteries is much better than that of LiCoO ₂ /C batteries, which reduces the cost of use and meets the requirements of energy storage batteries.

Example 2

First, polyvinylidene fluoride is added to an appropriate amount of N-methylpyrrolidone, stirred and dissolved to make a glue solution for use. Mix the negative electrode active material Li ₄ Ti ₅ O ₁₂ and carbon black into the above glue (Li ₄ Ti ₅ O ₁₂ : carbon black: polyvinylidene fluoride mass percentage = 75:15:10), stir and mix thoroughly , evenly coated on both sides of the aluminum foil (thickness 15μm) to make a negative electrode sheet. Similarly, the positive electrode active material LiFePO ₄ and carbon black are mixed and added to the above-mentioned glue solution (LiFePO ₄ : carbon black: polyvinylidene fluoride by mass percentage = 80:12:8), after fully stirring and mixing, evenly apply it on aluminum foil ( The two sides with a thickness of 30 μm) are made into positive electrode sheets.

The positive and negative electrode sheets prepared above were vacuum-dried at 80° C. for 6 h, rolled and punched. After the positive and negative plates are separated by a diaphragm, they are stacked into batteries. The battery cell is put into a square aluminum shell, welded, injected with liquid, and sealed to make a square battery.

Claims (8)

1, a kind of energy-storage battery based on lithium ion conduction constitutes electrolyte by the non-aqueous solution that contains lithium salts, it is characterized in that constituting negative pole main body active material by lithium titanate, constitutes anodal main body active material by LiMn2O4 or LiFePO 4.

2, by the described energy-storage battery of claim 1 based on lithium ion conduction, it is characterized in that the described nonaqueous solution electrolysis liquid that contains lithium salts is ethylene carbonate, dimethyl carbonate and the methyl ethyl carbonate of 1M lithium hexafluoro phosphate, wherein the volume ratio of ethylene carbonate, dimethyl carbonate and methyl ethyl carbonate is 1:1:1.

3, by the described energy-storage battery of claim 1, it is characterized in that anodal main body active material or negative pole main body active material are coated in the aluminium foil two sides, constitute positive plate or negative plate based on lithium ion conduction.

4, by the described energy-storage battery of claim 3, it is characterized in that described aluminum foil thickness is 15-30 μ m based on lithium ion conduction.

5, make method, it is characterized in that making step is as each described energy-storage battery based on lithium ion conduction among the claim 1-3:

A) will gather inclined to one side chlorine PVF binding agent and join in the N-methyl pyrrolidone solution, after stirring and dissolving, be pressed into glue;

B) anodal main body active material or negative pole main body active material, carbon black, binding agent are joined in the glue of step a preparation for the ratio of 70-95%:20-20%:3-10% by mass percentage; Coat the aluminium foil two sides after stirring and constitute electrode slice; The quality of described solvent be active material quality to be added 0.5-2 doubly;

C) electrode film or the negative electrode plate vacuum drying that step b is made after cutting into positive and negative plate after the roll-in and being separated by barrier film, through reeling or lamination becomes electric core, dress shell, welding, fluid injection, seals and makes battery.

6, by the manufacture method of the described energy-storage battery based on lithium ion conduction of claim 5, it is characterized in that the battery of making is cylindrical battery or rectangular cell.

7, by the manufacture method of the described energy-storage battery based on lithium ion conduction of claim 5, it is characterized in that cell forms module through after the sorting, by the energy storage demand module is assembled into battery pack again.

8, by the manufacture method of the described energy-storage battery based on lithium ion conduction of claim 7, it is capacity tolerance ± 1.0%, internal resistance deviation ± 0.3m Ω, charge and discharge platform deviation ± 2mV and self-discharge rate ± 1.0% that the sorting that it is characterized in that described cell requires.

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