KR101327511B1 - Electrode using natural substance including calcium carbonate, and method for producing the same - Google Patents

Abstract

The present invention relates to an electrode using a natural substance including calcium carbonate, and a method for producing the same. The method includes a step of incinerating natural materials including CaCO3 and a step of forming an electrode using the calcined natural materials.

Description

Electrode using natural substance including calcium carbonate, and method for producing the same}

The present invention relates to an electrode using a natural material containing calcium carbonate, a method for producing the same, and a battery including the electrode.

Lithium-ion batteries have attracted much attention in the scientific and human communities due to their high energy density, low weight, ease of handling, high cell voltage, safe operation, long cycles and long life, and low self-discharge characteristics. It is widely used in various fields such as PC, camcorder and aerospace industry.

Despite significant advances over the last few years, state-of-the-art lithium ion batteries are still lacking in safety, environmental issues, operating temperature and cost effectiveness. In order to improve the electrochemical performance of new types of anode materials, the determination of the anode reaction mechanism is necessary for lithium ion batteries. However, cost, safety, stored energy density, charge / discharge rate, and lifespan continue to hinder the development of potential mass market lithium ion batteries for portable electronics to mitigate widespread CO ₂ emission and noise pollution in the atmosphere. to be.

Carbon materials have been used as anode materials, which have a lower capacity than non-carbon based anodes for lithium ion batteries. Recently, biomaterial-based devices have been developed, which have strong chemical and electrochemical effects and at the same time have the unique properties of obtaining nanostructures. The development of environmentally friendly biomaterials that yield more power with high speed performance is important for high power applications. Biomineral based crystalline materials were the goal of biomimetic research because of their unique structural arrangements and interesting mechanical properties. Determining the structure of biological materials is the most important challenge in understanding all the properties and mechanisms for designing new generations of biomimetic materials. Increasing knowledge about the boundary region between biological molecules and inorganic materials has led to new approaches in the design and manufacture of artificial devices.

Various biomolecules, including DNA, peptides and proteins, have been functionalized, assembled into nanostructures, and implemented in electronic devices such as biosensors, transistors, portable memory devices, and battery electrode materials. Bio-viral genes with great affinity for single-walled nanotubes (SWNTs) have enabled the output performance of FePO ₄ for lithium ion batteries. In the future, biologically based soft devices for power generation may provide an alternative to current solid state energy technologies. It also has the potential to be less expensive and more environmentally friendly than current energy devices. The biomaterial (egg shell) consists mainly of 97% calcium carbonate, 2% magnesium carbonate and 1% other biomineral crystals. In addition, non-aqueous calcium and magnesium based cells can provide a potential ultra high energy density power source.

Korean Patent Laid-Open Publication No. 2009-105786 discloses a lithium-transition metal composite compound having an n-th order hierarchical structure derived from natural materials, a method for preparing the same, and a lithium battery having an electrode including the same. However, in this patent only natural materials were used to obtain carbides.

Japanese Patent Laid-Open No. 2001-52706 discloses a method of removing impurities such as metal oxides contained in waste of crops and manufacturing a carbon material for electrode material of a secondary battery. However, the crop waste in this patent was only used to obtain carbon material.

Japanese Patent Laid-Open No. 2001-266870 discloses a method of obtaining a carbonaceous material from crystalline cellulose such as walnut shell as a secondary battery negative electrode material. In this patent, however, walnut shells were only used to obtain carbon material.

Korean Patent Publication No. 2010-49556 discloses a method of mixing a compound containing a metal atom such as nickel and cobalt, a lithium compound and a calcium compound, and calcining the mixture to prepare a cathode active material containing a Ca atom. have. However, this patent does not use calcium compounds derived from natural substances, and includes Li, Ni, Co, etc. in addition to Ca, and the molar ratio of Ca atoms is only 0.001 to 0.05 to the total amount, that is, Ca is not a main component but a subcomponent. Only a small amount was used.

It is an object of the present invention to provide an electrode which is environmentally friendly and cost effective, and which has excellent thermal stability and electrochemical properties.

Another object of the present invention is to provide a method for producing the battery electrode.

Still another object of the present invention is to provide a battery such as a lithium ion battery including the electrode.

The present invention to achieve the above object, the step of calcining natural materials containing CaCO ₃ ; And it provides a method for producing an electrode comprising the step of forming an electrode using the calcined natural material.

In the present invention, the natural material including CaCO ₃ may be at least one selected from the group consisting of eggshell, clamshell, coral, calcite, marble, limestone, ice tin, berite and chalk.

In the present invention, the calcination temperature may be 500 to 900 ° C, preferably 600 to 900 ° C, more preferably 700 to 900 ° C, most preferably 750 to 850 ° C.

Forming the electrode of the electrode manufacturing method of the present invention comprises the steps of mixing the calcined natural material 60 to 98% by weight, the conductive material 1 to 20% by weight, and the binder 1 to 20% by weight to form a slurry; And applying the slurry onto a substrate and then drying.

In the present invention, the substrate may be selected from metal elements belonging to Groups 3 to 15.

The present invention also provides an electrode manufactured according to the above-described method, which can be used in a battery such as a lithium ion battery.

The electrode according to the present invention is environmentally friendly and inexpensive to manufacture using natural materials.

In addition, by using the calcined body obtained by calcining a natural material including calcium carbonate according to the present invention, the thermal stability and electrochemical properties of the electrode can be greatly improved.

1 is a manufacturing process chart of the calcined body used in the present invention.
FIG. 2 shows the results of XRD analysis of pure CaCO ₃ at 800 ° C. and biomaterial calcined at 600 ° C., 700 ° C. and 800 ° C. for 2 hours at room temperature.
Figure 3 shows the results of XRD analysis of pure CaCO ₃ and bio material in the absence of calcination.
4 shows SEM images of biomaterials calcined at (A) 600 ° C., (B) 700 ° C. and (C) 800 ° C. for 2 hours.
5 shows the results of SEM and EDX analysis of the biomaterial calcined at 600 ° C. for 2 hours.
6 shows SEM and EDX analysis of the biomaterial calcined at 700 ° C. for 2 hours.
7 shows the results of SEM and EDX analysis of the biomaterial calcined at 800 ° C. for 2 hours.
FIG. 8 shows the charge-discharge characteristics of biomaterials calcined at three different temperatures (600 ° C., 700 ° C. and 800 ° C.) using 1 M LiPF ₆ in EC + DEC 1: 1 (v / v).
9 shows the results of X-ray diffraction analysis.
FIG. 10 shows a typical Nyquist plot of AC impedance after completing charging up to 2.5 V in 20 cycles for three calcined biomaterial anode materials.
FIG. 11 shows a typical DSC curve for three calcined and lithium intercalated biomaterial anodes including an electrolyte and a binder.

Hereinafter, the present invention will be described in detail.

The present invention relates to an electrode using a natural material containing calcium carbonate and a method for producing the same, comprising the steps of calcining a natural material including CaCO ₃ ; And forming an electrode using the calcined natural material.

In the present invention, calcine means an operation of heating a substance to a high temperature to remove a part or all of the volatile components. For example, in the case of magnesium carbonate, the contained carbonic acid group is removed at 800 to 900 DEG C, and a calcined magnesia having a very small specific gravity can be obtained. The sintering of the constituent material at a higher temperature is not called calcination, and refers to a case where volatiles are removed at a temperature lower than the sintering temperature. The reaction that occurs upon calcination is, for example:

[Reaction Scheme 1]

CaCO ₃ → CaO + CO ₂ ↑

[Reaction Scheme 2]

MgCO ₃ → MgO + CO ₂ ↑

1 is a manufacturing process chart of the calcined body used in the present invention, this process consists of the washing, drying, grinding, ball-milling, calcining step of the natural material including CaCO ₃ to finally obtain a calcined powder in the form of Can be.

In the present invention, the natural material including CaCO ₃ may be used, for example, one selected from egg shells, clam shells, corals, calcite, marble, limestone, ice tin, berite, chalk, or a mixture of two or more. .

Among the natural materials, egg shell is a bio material, and 93.7% of the inorganic salts are inorganic salts. Inorganic salts in egg shells are mostly calcium carbonate, and other small amounts of magnesium carbonate and calcium phosphate. 4.75% organic matter and 1.5% moisture.

In the present invention, the calcination temperature may be 500 to 900 ° C, preferably 600 to 900 ° C, more preferably 700 to 900 ° C, most preferably 750 to 850 ° C. If the calcination temperature is too low or too high, some of the physical properties such as thermal stability and electrochemical properties of the electrode may be degraded.

Natural substances containing CaCO ₃ are converted to oxides through calcination, but structurally some still contain CaCO ₃ and contain traces of magnesium, phosphorus and fluorine.

Forming the electrode of the electrode manufacturing method of the present invention comprises the steps of mixing the electrode raw material to form a slurry; And applying the slurry onto a substrate and then drying.

The negative electrode raw material may be composed of 60 to 98% by weight of the calcined natural material, 1 to 20% by weight of the conductive material, and 1 to 20% by weight of the binder. On the other hand, as a positive electrode raw material, the present natural material may be used as an additive, and may be composed of 0.01 to 50% by weight. In consideration of the thermal stability and the electrochemical properties of the electrode, it is possible to selectively configure the added weight% according to the type of the positive electrode active material.

As the conductive material, for example, a metal material, a carbon material such as carbon black, or the like may be used, and as the binder, for example, polyvinylidene fluoride may be used.

The substrate may be pretreated before use, for example, pretreatment of the substrate may include degreasing with an organic solvent such as acetone, washing with an alkaline solution, washing and rinsing with distilled water, etching with hydrochloric acid, etc. It may consist of washing and rinsing steps.

As the substrate, one metal or two or more alloys can be selected from the metal elements belonging to Groups 3 to 15, and for example, copper, iron, nickel and the like can be used.

The electrode prepared as described above can be used in a battery. Batteries are small devices that convert the energy released by their changes into electrical energy using chemical or physical reactions of materials, and chemical cells can be divided into primary and secondary cells. The primary battery puts a working substance near the electrode in advance and uses electrical energy generated by chemical change of the substance. Once the chemical change of the agonist is over, it cannot reach the end of its lifetime. Widely used as battery. After the secondary battery releases the electric energy to change the active material, the secondary battery supplies the electrical energy to the battery again, ie, charges the active material to regenerate and repeat it. It is widely used as a storage battery. Physical cells include solar cells and thermal cells, and solar cells are composed of semiconductor junctions that directly convert sunlight into electrical energy.

Electrodes prepared using natural materials according to the present invention can be usefully used as electrode materials for lithium ion batteries. For example, the lithium ion battery may be composed of an anode, a cathode (Li, etc.), a porous separator, and an electrolyte (such as a lithium salt) using a natural material according to the present invention.

Precious metals such as gold and silver or carbon-based conductive materials are used to improve conductivity, and chemical substances including phosphorus and nitrogen have been used as additives to improve thermal stability. In the present invention, by using as an electrode material through a series of processes based on natural materials including CaCO ₃ , it is possible to improve the existing electrochemical or thermal properties. Egg shells, etc. are very easy to obtain as a natural material, and the processing process for the final use as a material is very simple, so it is very economical in terms of manufacturing cost, and most of all, it is environmentally friendly because it is a natural material.

Electrode material according to the present invention using a natural material containing CaCO ₃ is a very simple manufacturing process, low cost and very environmentally friendly. Generally, in order to improve electrochemical properties or thermal stability, additives for improving each property are separately used, while in the present invention, both properties can be satisfied at a certain level.

Natural materials used in the present invention can be applied to the field of new materials including electronic devices, batteries, energy devices, heat-resistant materials, etc., in particular, it is possible to further improve the electrochemical properties and thermal stability of the material for lithium batteries at a very low cost.

According to a preferred embodiment of the present invention, there is provided a new type of environmentally friendly biomaterial based electrode that can be used for the next generation of emissive electrode materials of lithium ion batteries. Biomaterials may be synthesized at a specific range of calcination temperatures (600-800 ° C.) by mechanical alloying processes. The calcined biomaterial can be well ordered into single crystals and have a high specific capacity. Lithiated biomaterials can form CaO, CaC ₂ , CaF ₂ , CaOC ₂ , CaOF ₂ and Ca (OOC) ₂ chemical compounds with semicrystalline properties. In particular, the biomaterial calcined at 800 ° C. can be crystallized well, exhibit electrochemically stable properties, and exhibit excellent thermal stability, with insignificant levels of exothermic and endothermic reactions up to 400 ° C. In addition, due to the lower charge-transfer impedance, the electrical conductivity can be significantly improved, and the electrochemical cycling performance can be significantly improved compared to other calcined biomaterials. Therefore, this biomaterial can be very usefully used as an electrode material having high thermal stability and economical efficiency for lithium ion batteries.

In the present invention, the cycle (ring) performance (cycle) is related to the battery life, the excellent cycle (ring) performance can be said that the capacity is continuously maintained while the battery is repeatedly used for several tens of cycles or more.

Hereinafter, the present invention will be described in more detail with reference to Examples and drawings. The following examples are provided to illustrate the present invention, but the scope of the present invention is not limited thereto.

[Example]

The biomaterial-based calcined powder was obtained using the mechanical milling method shown in FIG. 1. Egg shell was used as bio material, and the calcining temperature was varied at 600 ° C, 700 ° C, and 800 ° C.

To prepare the anode material, 80 wt% of the calcined biomaterial, 10 wt% of N330 (superblack) as the conductive material, 10 wt% of polyvinylidene fluoride (PVdF) binder was added to N-methyl-2-pyrrolidone ( NMP). After the mixture was ground for 15 minutes to form a viscous slurry, the viscous slurry formed was applied onto a copper foil and dried at 100 ° C. for 5 hours in an oven. The dried coating electrode was pressed under a 7 ton / cm 2 load, and then punched into size 14 mm in diameter to use as anode. The punched anode was further dried at 120 ° C. for 5 hours in a vacuum oven. The electrode film was about 44 μm thick.

[Test Example]

XRD patterns for the three calcined biomaterials were obtained using Cu Kα radiation (λ = 1.5406 Hz) in the 2θ range of 10-80 ^° using an X-ray diffractometer (D8 Discover with GADDS, Bruker AXS). Morphology and spectral analysis of the obtained powder were observed using a scanning electron microscope (SEM + EDX, Leo Supra 55, Genesis 2000, Carl Zeiss).

Pure Li foil having a diameter of 16 mm was used as a reference electrode. 2032 coin-shaped cells (diameter 20 mm, thickness 3.2 mm) were assembled in a glove box under high purity argon atmosphere (<1 mg / LO ₂ and H ₂ O). The cell consisted of a composite anode prepared as a working electrode, a pure Li metal as a reference electrode, and a microporous membrane (Celgard 3501) as a separator, and the nonaqueous electrolyte used was ethylene carbonate provided by StarLyte, Ukseung Chemical Co., Ltd. It was 1 M LiPF ₆ (lithium hexafluoro phosphate) dissolved in a 1: 1 mixture by volume of (EC) and diethyl carbonate (DEC). The open-circuit potential of the composite anode was in the range of 2.8 to 3.0 V for Li / Li ⁺ in the delithiated state. The electrochemical properties of the three calcined biomaterial anode active materials were investigated at room temperature. The prepared coil cell was charged at 0.01 V for Li / Li ⁺ (Li ⁺ insertion) and then discharged at 2.5 V for Li / Li ⁺ at a constant current density of 0.1 mA / cm 2 using Arbin equipment (Li ⁺ Tally). Twenty cycles later, electrochemical analysis was performed on a two-electrode cell using cyclic voltammetry and AC impedance cycling, and three compact calcined biomaterials as working electrodes and compactstat (purestat) for pure Li foils as reference and counter electrodes. IVIUM Technologies).

DSC sample preparation initially consists of the insertion of three biomaterial based anode materials. Three calcined biomaterials were performed in a 2032 coin cell type using lithium metal as counter electrode at the same current density. The biomaterial based cell was discharged to 0.01 V and charged to 2.5 V, and after 50 cycles the calcined anode in full charge was transferred to a glove box under high purity argon atmosphere. About 1.5-2.5 mg of active material was taken, then placed in an aluminum DSC cell and sealed with crimping. The lithium metal and separator were discarded and all DSC calculations were based on the total weight of the sample. DSC experiments were performed at a ramp rate of 10 ° C./min using DSC equipment (DSC Q1000 V9.9 build 303 Differential scanning calorimetry TGA instrument), and the lamp range used was from room temperature to 400 ° C. The exothermic and endothermic reactions were then plotted with positive and negative heat flows respectively as a function of temperature.

Figure 2 is a comparison of three kinds to a different calcination temperature to show a single crystal biomaterials based anode material prepared by the mechanical milling method, and of the carbon matrix Ca ^{+ 2} and pure CaCO ₃ in the solid dispersion of the Mg ^{+ 2.} According to powder X-rays, the biomaterial egg shells consisted of CaCO ₃ in the form of calcite. This material exhibited a single phase diffraction pattern and the calcined FCC (face-centered cubic lattice) crystal powder consisted mainly of calcite. This is based on the eggshell cubic lattice structure and the XRD pattern of the eggshell by peak and intensity and determined the preferred orientation of the crystallites. Characteristics such as lattice constants, d-spacing values, and volumes of the main diffraction peaks were calculated and summarized in Table 1.

The average size of the crystallites was determined by the full width at half maximum (FWHM) of the peaks 104, as distinguished by the Scherrer equation, and the average crystal size of the biomaterial was 500-800 nm. Increasing the calcination temperature caused the crystal d-spacing and cell volume of the biomaterial to expand. The expansion of the lattice crystals could provide more lattice space for lithium insertion and desorption. The Li ⁺ desorption process, the grid is to be protected from the shrinkage caused by heat and crystalline Ca ^{2 +} and Mg ^{2 +} due to the larger volume of the crystal. The biomaterials synthesized according to the invention were in full agreement with existing results for outer egg shells. Although it is known to crystallize well with increasing calcining temperature in relation to the crystal structure of three calcined biomaterials, pure CaCO ₃ crystal phase material at 800 ° C. was completely different from the biomaterials synthesized according to the present invention. As shown in FIG. 3, biomaterials without calcination and pure CaCO ₃ were compared. The biomaterial and pure calcium carbonate showed almost the same X-ray diffraction pattern and did not differ structurally.

Form and particle size play an important role in the electrochemical cycling performance of lithium ion cells. The surface morphology and particle shape of the samples were examined by SEM equipment. 4 shows a typical SEM image of the synthesized biomaterial. According to the SEM micrographs, the three calcined biomaterials were triangular polyhedral particles. 1 μm was observed, with the clusters forming a soft aggregate. The presence of Ca and a small amount of Mg resulted in the ultrafine natural particles in the particles, attempting to form a large triangular rock composed of oxide layer fragments fused together, with an average particle size of 500-800 nm. Increasing the calcination temperature of the biomaterial, the anode material formed a triangle at 800 ° C. as shown in the last photo of FIG. 4, which is advantageous in terms of electrochemical cycling performance and mechanical stability. Thus, the biomaterial calcined at 800 ° C. is an anode material suitable for next generation lithium ion batteries.

5 to 7 show the qualitative and quantitative results of the biomaterial (egg shell) structure by energy dispersive x-ray (EDX) analysis. According to the EDX analysis, the three calcined biomaterials consisted of the following elements: carbon, oxygen, magnesium and calcium (in relatively abundant order), as shown in Table 2. Weight% and atomic% can be calculated | required by the following formula.

[Equation 1]

% By weight = atomic weight of specific element / atomic weight of all elements

&Quot; (2) &quot;

Atomic% = number of atoms of a specific element / number of atoms of all elements

element Biomaterial-600 ℃ Biomaterial-700 ℃ Biomaterial-800 ℃ weight% atom% weight% atom% weight% atom% C
O
Mg
Ca 27.2133
47.0462
0.2134
25.5269 38.74
50.23
0.15
10.88 26.1332
48.3365
0.2396
25.2905 37.55
52.09
0.17
10.19 18.9214
49.7520
0.3185
31.0079 28.64
56.95
0.24
14.17 Sum 100 100 100

FIG. 8 shows the cycle characteristics during discharge of 2032 cells obtained using 80% of the biomaterial obtained at different calcination temperatures. The discharge characteristics of biomaterials calcined at three different temperatures (600 ° C., 700 ° C. and 800 ° C.) using 1 M LiPF ₆ in EC + DEC 1: 1 (v / v) are shown. Specific capacity analysis for the potential was performed at a constant 0.1 mA / cm 2 current density of C / 10 speed and a potential range of 0.01 to 2.5 V for Li / Li ⁺ in the three calcined biomaterial anode materials. The biomineral compounds calcined at 600 ° C., 700 ° C. and 800 ° C. initially delivered 609.28, 829.02 and 934.6 mAh / g, and the specific discharge capacity of the three calcined bio materials after the third cycle was constant up to 20 cycles. Maintained. Biomaterials calcined at 800 ° C. had better electrochemical life cycling performance than biomaterials calcined at other temperatures because of the structure of the biomaterials having good crystal properties, especially in high temperature calcination processes. The material synthesized in the present invention can form Li-C, Li-Ca and Li-Mg alloys as shown in Schemes 3 to 6, because it consists of the maximum amount of CaO and the minimum amount of MgO in the biomaterial. to be. In other words, calcium and magnesium elements or processes transfer electrons to the carbon structure and involve both oxidation and reduction reactions. In addition, the Ca and Mg elements act as buffer matrices in the biomaterial anode material and improve electrochemical reversibility after the third cycle.

In particular, the biomaterial anode, elemental Ca and small amounts of Mg are inert to Li, and Li _y C, Li _y Ca _x and Li _y Mg _x alloys may be reactive to Li. In contrast, the biomaterial and Li react with the Li alloy to form lithiated compounds (yLiMg _x C and yLiCa _x C). Therefore, based on the change, and the surface doped with Li to Ca and Mg, the following mechanism is proposed for the reaction of the bio-material and Li (Li surface, to reduce all of the Ca ^{2 +} and Mg ^{2 +} ions, thus Li- Ca and Li-Mg surface alloys). The reaction mechanism of biomaterials is more complicated than other anode materials. Lithiation and delithiation of the biomaterial anode in the first cycle can be described by the following process.

Scheme 3

Li + (EC, DEC, ... ) + e - → SEI (Li 2 CO 3, ROCOOLi, ...)

[Reaction Scheme 4]

^{C + xCaO + yLi + + ye} - → Li y O x + yLiC + Li y Ca x

[Reaction Scheme 5]

^{C + xMgO + yLi + + ye} - → Li y O x + yLiC + Li y Mg x

[Reaction Scheme 6]

CaO + MgO + yLi ⁺ + C + ye ^- → Li _y O _x + yLiC yLiMg _x + C _x + C yLiCa

These alloys have improved the performance of Li electrodes or lithium rechargeable batteries including these modifications at high charge rates. As it turns out, the best performance of the secondary battery in terms of cycle life was obtained at any speed. Specifically, referring to the X-ray diffraction analysis results and Schemes 7 to 10 of FIG. 9, after 20 cycles, the biomaterial anode is used to obtain CaO, CaC ₂ , CaF ₂ , CaOC ₂ , CaOF ₂ and Ca (OOC) ₂ chemical compounds. Formed. The lithiated and delithiated reaction mechanisms of biomaterials were more complicated than carbon anode materials. Lithiation and delithiation of the biomaterial anode in the first cycle can be described by the following reaction mechanism.

[Reaction Scheme 7]

xLi + C + CaO + MgO + 2LiPF ₆ → Li _x C + CaF ₂ + MgF ₂ + 2LiF + 2PF ₃ O

[Reaction Scheme 8]

CaF ₂ + 2H ₂ O → CaOF ₂ + 2H ₂ ↑

[Reaction Scheme 9]

MgF ₂ + 2H ₂ O → MgOF ₂ + 2H ₂ ↑

[Reaction Scheme 10]

xLi + C + 2CaO + 2MgO + 2LiPF ₆ → Li _x C + 2CaMgOF ₂ + 2LiF + 2PF ₃ O

FIG. 10 shows a typical Nyquist plot of AC impedance after completing charging up to 2.5 V in 20 cycles for three calcined biomaterial anode materials. AC impedance spectra were obtained within a frequency range of 10 ⁻² Hz to 10 ⁵ Hz. In general, the impedance spectra of the three calcined biomaterial anodes are followed by a straight line that is inclined at a constant angle. According to the model proposed by some existing studies, the shape of a crooked arc consists of two semicircles in the high frequency region and an inclined straight line in the low frequency region. The first half circle in the high frequency region is due to the solid electrolyte interface (SEI) film and / or the constant resistance, the second half circle in the middle frequency region is due to the charge-transfer resistance on the electrode / electrolyte interface of the lithium ion cell, The oblique line at an angle of about 45 ^° to the actual axis corresponds to lithium diffusion kinetics for the electrode. As can be clearly seen in FIG. 10, the diameter of the semicircle in the high frequency region of the biomaterial at 800 ° C. was greatly reduced due to the lower charge transfer resistance. The biomaterial anode calcined at 800 ° C. had a lower charge-transfer impedance, resulting in significantly improved electrical conductivity and well-organized single crystal properties, which resulted in electrochemical comparison with other calcined biomaterials for lithium ion batteries. Cycling performance is significantly improved. The biomaterial calcined at 800 ° C. is well ordered into single crystals and can be applied as an environmentally friendly anode material for next generation Li ion batteries.

Differential scanning calorimetry (DSC) is a useful tool for analyzing the thermal properties of anode and cathode materials for lithium ion batteries. Anisotropic thermal expansion of the outer egg shell is due to amorphous biopolymer calcite interactions, causing phenomena such as monocrystallization and rearrangement from the a to c-axis by the calcined sample. FIG. 11 shows typical DSC curves for three calcined (600 ° C., 700 ° C. and 800 ° C.) lithiated biomaterial anodes including electrolyte and binder. Lithiated biomaterial samples calcined at 600 ° C. generated heat, starting at 100 ° C. and exhibiting small peaks at 120 ° C., due to a broken SEI layer on the electrode surface. Gentle heat generation continued until sharp exothermic peaks appeared at 170 ° C., which completely degraded the biomaterial calcined at 600 ° C. Biomaterial samples calcined at lithiated 700 ° C. did not show small peaks at 120 ° C., and heat generation continued until 100 ° C. and sharp sharp exothermic peaks at 175 ° C., resulting in materials calcined at 700 ° C. High heat was generated at. There was no exothermic and endothermic reaction up to 400 ° C. for biomaterial samples calcined at 800 ° C. lithiated, which means that the bio material calcined at 800 ° C. is more thermally stable than other calcined bio materials. This is due to the rearrangement of the crystals, which can be assumed to be anisotropic thermal expansion of calcite. Changing the orientation will also change the thermal expansion behavior, and as the calcination temperature increases, the thermal and structural stability also increases. This biomaterial is therefore suitable as a thermally and electrochemically stable electrode material.

As mentioned above, a new kind of biomaterial anode was synthesized at three different calcining temperatures (600 ° C., 700 ° C. and 800 ° C.) by mechanical milling methods. Three calcined biomaterials consisted of CaCO ₃ in calcite form and exhibited a single phase FCC crystal diffraction pattern. As the calcination temperature increased, the average d-spacing and lattice constants increased, and the average particle size of the biomaterial calcined at 800 ° C due to the presence of C, O, Ca and a small amount of Mg in terms of atomic% was different. It was smaller than the bio material anode material. The electrochemical cycling properties of the calcined biomaterial at 800 ° C. showed stable behavior after several cycles, and thus the material could be used as a high capacity and high energy density material compared to other calcined biomaterials. The biomaterial anode calcined at 800 ° C. exhibited electrochemically stable interfacial properties due to the smaller charge transfer resistance between the electrode and electrolyte interface and was thermally more stable than other calcined biomaterials. Thus, biomaterial based anodes are effective and environmentally friendly anode materials for advanced lithium ion batteries.

Claims (8)

Calcining natural materials comprising CaCO ₃ ; And
Forming an electrode using a calcined natural material.
The method of claim 1,
The natural material containing CaCO ₃ is an electrode shell, clam shell, coral, calcite, marble, limestone, ice tin, berite and chalk production method of the electrode, characterized in that at least one selected from the group consisting of.
The method of claim 1,
Calcination temperature is a method for producing an electrode, characterized in that 500 to 900 ℃.
The method of claim 1,
Forming an electrode
Mixing 60 to 98 wt% of the calcined natural material, 1 to 20 wt% of the conductive material, and 1 to 20 wt% of the binder to form a slurry; And
Method of producing an electrode comprising the step of applying a slurry on a substrate and then drying.
5. The method of claim 4,
The substrate is a method of manufacturing an electrode, characterized in that selected from the metal elements belonging to Groups 3 to 15.
Electrode prepared according to any one of claims 1 to 5.
A battery comprising the electrode of claim 6.
The method of claim 7, wherein
The battery is a lithium ion battery.

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