Patent Application
20150357638
The present invention relates to a cathode active material for a lithium secondary battery, a method for manufacturing the same, and a lithium secondary battery using the same. More particularly, the present invention relates to a cathode active material capable of improving cycle life and charge/discharge characteristics of a lithium secondary battery by means of at least one coating layer formed on a surface of the cathode active material, a method for manufacturing the same, and a lithium secondary battery using the same.
Recently, portable electronic products such as a camcorder, a portable phone and a notebook personal computer have been generally used with the rapid development of electronic, communication and computer industries, so light, long-lifetime and high-reliable batteries have been demanded. In particular, a lithium secondary battery has an operating voltage of 3.7V or more, so an energy density per a unit weight of the lithium secondary battery is higher than those of a nickel-cadmium battery and a nickel-hydrogen battery. Thus, the lithium secondary battery has been increasingly demanded as a power source for driving the portable electronic, information and communication devices.
Recently, in U.S.A., Japan, and Europe, researches have been actively conducted for a power source of a hybrid electric car which can be formed by hybridizing an internal-combustion engine and the lithium secondary battery. A plug-in hybrid electric vehicle (P-HEV) battery used in a car traveling 60 miles or less a day has been actively developed primarily in U.S.A. The P-HEV battery has characteristics closer to those of an electric car, so it is required to develop a high-capacity battery. In particular, it may be required to develop a cathode material having a tap density of 2.0 g/cc or more and a high-capacity of 230 mAh/g or more.
LiCoO2, LiNiO2, LiMnO2, LiMn2O4, and LiFePO4 correspond to cathode materials which are commercialized or still under development. Among them, LiCoO2 is an excellent material having a stable charge/discharge characteristic, excellent electronic conductivity, a high battery voltage, high stability, and an even discharge voltage characteristic. However, since little Co is deposited and Co is expensive and poisonous to a human body, it is required to develop a now cathode material. In addition, a crystal structure of Co is unstable in charging by delithiation, so a thermal characteristic of Co is very poor.
To solve these, a transition metal element may be substituted for a portion of nickel to move a heat-generating start temperature to a high-temperature, or a heat-generating peak may become broad to prevent a sharp increase in temperature. However, the expected results have failed to come.
In other words, LiNi1−xCoxO2 (x=0.1-0.3) obtained by substituting cobalt for the portion of nickel has excellent charge/discharge and cycle life characteristics but does not have thermal stability. In addition, European Patent No. 0872450 discloses LiaCobMncMdNi1-(b+c+d)O2 (M=B, Al, Si. Fe, Cr, Cu, Zn, W, Ti, Ga) obtained by substituting Co, Mn and another nickel for nickel. However, the thermal stability problem of a Ni-based material does not solved.
To solve this problem, Korean patent publication No. 10-2005-0083869 discloses a lithium transition metal oxide in which a metal composition has a concentration gradient. According to this method, an internal material having a constant composition is synthesized, and a material having a different composition is coated on the internal material to manufacture a double layer. Thereafter, the double layer is mixed with lithium salt, and the mixture is thermally treated. A lithium transition metal oxide may be used as the internal material. However, a metal composition of a cathode active material is discontinuously changed between the internal material and external material which are generated, so an internal structure is unstable.
In addition, Korean Patent Registration No. 10-0693822 discloses a cathode active material having a substituted result concentration gradient. According to this, a concentration gradient is formed at an interface region of a core and a coating layer by coating or substitution to improve quality of a surface. However, the concentration gradient is not formed on the whole.
The present invention provides a cathode active material having a new structure including at least one coating on a surface, a method for manufacturing the same, and a lithium secondary battery including the same.
Embodiments of the present invention provide a cathode active material for a lithium secondary battery.
At least one coating layer is formed on a surface of the cathode active material.
The cathode active material includes: a core portion represented by the following chemical formula 1; and
a surface portion represented by the following chemical formula 2.
Lia1M1x1M2y1M3z1M4wO2+δ [Chemical formula 1]
Lia2M1x2M2y2M3z2M4wO2+δ [Chemical formula 2]
In the chemical formulas 1 and 2, “M1”, “M2”, and “M3” are selected from the group consisting of Ni, Co, Mn, and any combination thereof, “M4” is selected from the group consisting of Fe, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb, Mo, Al, Ga, B, and any combination thereof, 0<a1≦1.1, 0<a2≦1.1, 0≦x1≦1, 0≦x2≦1, 0≦y1≦1, 0≦y2≦1, 0≦z1≦1, 0≦z2≦1, 0≦w≦0.1, 0.0≦δ≦0 0.5, 0<x1+y1+z1≦1, 0<x2+y2+z2≦1, y1≦y2, and z2≦z1.
In an embodiment of the present invention, the coating layer may include at least one element selected from a group consisting of P, Zr, Sc, Y, Li, Na, K, Rb, Mg, Ca, Sr, Ba, La, Ti, V, Nb, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, B, Al, Ga, In, Si, Ge, Sn, Pb, As, Sb, Bi, Se, Te, and any combination thereof.
In an embodiment of the present invention, the coating layer may be represented by the following chemical formula 3.
DpJqOr [Chemical formula 3]
In the chemical formula 3, “D” is selected from a group consisting of P, Zr, Sc, Y, Li, Na, K, Rb, Mg, Ca, Sr, Ba, La, Ti, V, Nb, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, B, Al, Ga, In, Si, Ge, Sn, Pb, As, Sb, Bi, Se, Te, and any combination thereof.
In the chemical formula 3, “J” is selected from a group consisting of Li, Na, K, Rb, Mg, Ca, Sr, Ba, Y, La, Ti, Zr, V, Nb, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, B, Al, Ga, In, Si, Ge, Sn, Pb, As, Sb, Bi, Se, Te, and any combination thereof, 0<p≦4, 0≦q≦1, and 0<r≦10.
In an embodiment of the present invention, the coating layer may be selected from a group consisting of ZrO2, PO4, SeO3, and SnO2. Since the cathode active material according to an embodiment of the present invention includes the coating layer selected from a group consisting of ZrO2, PO4, SeO3, and SnO2, stability and conductivity of the cathode active material may be improved together.
In an embodiment of the present invention, the coating layer may be single-layered or multi-layered and may have an island shape. If the coating layer has a layered shape, the coating layer can be uniformly coated. If the coating layer has the island shape, the coating layer may selectively react with a specific active point of the surface of the active material. Thus, side reaction can be controlled and electrical characteristics and thermal stability can be improved.
Electrochemical characteristics of the cathode active material of the present invention may be varied depending on a content of the coating layer. If a coating material is added, a coating element may be physically or chemically combined with the inside of a particle or between particles. Thus, when particles are firstly formed during a subsequent thermal treatment (e.g., in an air atmosphere), particles may be prevented from being bonded to each other and growth of the particles may be inhibited.
In an embodiment of the present invention, a thickness of the coating layer may be in a range of 1 nm to 150 nm.
In an embodiment of the present invention, the cathode active material for the lithium secondary battery including the core portion represented by the chemical formula 1 and the surface portion represented by the chemical formula 2 may be prepared in the following manner:
A thickness of the core portion may be in a range of 10% to 70% of a total size of a particle of the cathode active material for the lithium secondary battery, and
a concentration of metal ions from the core portion to the surface portion may be uniformly represented by the chemical formula 2.
In an embodiment of the present invention, the cathode active material for the lithium secondary battery including the core portion represented by the chemical formula 1 and the surface portion represented by the chemical formula 2 may be prepared in the following manner:
A thickness of the core portion is in a range of 10% to 70% of a total size of a particle of the cathode active material for the lithium secondary battery,
a thickness of the surface portion is in a range of 1% to 5% of the total size of the particle of the cathode active material for the lithium secondary battery, and
concentrations of M1, M2, and M3 have continuous concentration gradients from the core portion to the surface portion.
In an embodiment of the present invention, the cathode active material for the lithium secondary battery including the core portion represented by the chemical formula 1 and the surface portion represented by the chemical formula 2 may be prepared in the following manner:
A thickness of the core portion and a thickness of the surface portion range from 1% to 5% of a total size of a particle of the cathode active material for the lithium secondary battery, and
concentrations of M1, M2, and M3 have continuous concentration gradients from the core portion to the surface portion.
In an embodiment of the present invention, the cathode active material for the lithium secondary battery including the core portion represented by the chemical formula 1 and the surface portion represented by the chemical formula 2 may be prepared in the following manner:
The concentrations of M1 and M2 have continuously increasing concentration gradients from the core portion to the surface portion, and the concentration of M3 has continuously decreasing concentration gradient from the core portion to the surface portion.
In an embodiment of the present invention, the cathode active material for the lithium secondary battery including the core portion represented by the chemical formula 1 and the surface portion represented by the chemical formula 2 may be prepared in the following manner:
A thickness of the core portion and a thickness of the surface portion range from 1% to 5% of a total size of a particle of the cathode active material for the lithium secondary battery,
a concentration of M1 is uniform from the core portion to the surface portion, and
concentrations of M2 and M3 have continuous concentration gradients from the core portion to the surface portion.
In an embodiment of the present invention, the chemical formula 1 or 2 may satisfy conditions of 0≦|x2−x1|≦0.4, 0.01≦|y2−y1|≦0.4, 0.1≦|z2−z1|≦0.5, 0.15≦x2≦0.35, 0.01≦y2≦0.3, and 0.5≦z2≦0.7.
At this time, in an embodiment of the present invention, the concentration of M3 may decrease from 0.90 molar ratio of the core portion to 0.65 molar ratio of the surface portion and the concentration of M2 may increase from 0.05 molar ratio of the core portion to 0.10 molar ratio of the surface portion. The concentration of M1 may increase from 0.05 molar ratio of the core portion to 0.25 molar ratio of the surface portion.
In another embodiment of the present invention, the concentration of M3 may be 0.75 molar ratio at the core portion but may decrease to 0.55 molar ratio at the surface portion. The concentration of M2 may increase from 0 molar ratio of the core portion to 0.20 molar ratio of the surface portion. The concentration of M1 may be uniformly 0.25 molar ratio at the core portion and the surface portion.
In an embodiment of the present invention, a particle size of the cathode active material for the lithium secondary battery is in a range of 0.1 μm to 1 μm, and more particularly, in a range of 0.1 μm to 0.6 μm. If the particle size of the cathode material is smaller than 0.1 μm, a tap density may be reduced. If the particle size of the cathode material is larger than 1.0 μm, the tap density may increase. However, since the particle size is too large, insertion and desorption distances of lithium ions are long in the structure to deteriorate electrochemical characteristics of a battery.
In an embodiment of the present invention, the cathode active material for the lithium secondary battery including the core portion represented by the chemical formula 1 and the surface portion represented by the chemical formula 2 may be prepared in the following manner: the M1 is Co, the M2 is Mn, and the M3 is Ni.
In an embodiment of the present invention, the cathode active material for the lithium secondary battery including the core portion represented by the chemical formula 1 and the surface portion represented by the chemical formula 2 may be prepared in the following manner: the M1 is Mn, the M2 is Co, and the M3 is Ni.
In an embodiment of the present invention, the cathode active material for the lithium secondary battery including the core portion represented by the chemical formula 1 and the surface portion represented by the chemical formula 2 may be prepared in the following manner: the M1 is Ni, the M2 is Co, and the M3 is Mn.
Embodiments of the present invention also provide a method for manufacturing a cathode active material for a lithium secondary battery. The method includes:
synthesizing a coating layer source material;
forming a cathode active material precursor for a lithium secondary battery;
mixing the coating layer source material and lithium salt with the cathode active material precursor for the lithium secondary battery to form a mixture; and
baking the mixture.
Embodiments of the present invention also provide a method for manufacturing a cathode active material for a lithium secondary battery. The method includes:
synthesizing a coating layer source material;
forming a cathode active material for a lithium secondary battery;
mixing the coating layer source material and the cathode active material with a solvent to form a mixture;
coating and drying the mixture; and
baking the coated and dried mixture.
In an embodiment of the manufacturing method of the present invention, the solvent may be selected from a group consisting of distilled water, methanol, ethanol, and any combination thereof.
In an embodiment of the manufacturing method of the present invention, the coating layer source material may be mixed at a ratio of 0.1 wt % to 1.00 wt % with respect to 100 wt % of the cathode active material.
If a mixing ratio of the coating layer source material is lower than 0.1 wt %, the effect by coating may not be shown. If a mixing ratio of an oxide of the coating element is higher than 1.00 wt %, the coating layer may be too thick to disturb insertion and desorption of lithium ions. Thus, conductivity may be deteriorated.
Embodiments of the present invention also provide a lithium secondary battery including a cathode active material on which at least one coating layer is formed.
The cathode active material of the present invention includes at least one coating layer which includes an oxide of a coating element and is formed on the surface of the cathode active material, and thus, the stability and electrical conductivity of the cathode active material are improved. In addition, the battery including cathode active material has excellent charge/discharge and cycle life characteristics and excellent thermal stability.
Hereinafter, exemplary embodiments of the present invention will be described in detail. However, it should be noted that the present invention is not limited to the following exemplary embodiments and may be implemented in various forms. Accordingly, the exemplary embodiments are provided only to disclose the present invention and let those skilled in the art know the category of the present invention.
To manufacture a particle including a core having a constant concentration and a shell having a constant concentration, an aqueous metal salt solution (2.4 M concentration) for forming a core portion was prepared by mixing nickel sulfate, cobalt sulfate, and manganese sulfate with each other at a molar ratio of 90:5:5, and an aqueous metal salt solution for forming a surface portion was prepared by mixing nickel sulfate, cobalt sulfate, and manganese sulfate with each other at a molar ratio of 65:10:25. After 4 liter distilled water was provided into a co-precipitation reactor (having capacity of 4 L and including a rotary motor with an output power of 80 W), a nitrogen gas was supplied into the reactor at a rate of 0.5 liter/min to remove dissolved oxygen and the distilled water was stirred at a speed of 1000 rpm in the reactor maintained at a temperature of 50° C.
The aqueous metal salt solution for forming the core portion was provided into the reactor to form a core, and then, the aqueous metal salt solution for forming the surface portion was provided into the reactor at a rate of 0.3 liter/min to form an active material precursor including the core having the constant concentration and the shell having the constant concentration.
An aqueous metal salt solution (2.4 M concentration) for forming a core portion was prepared by mixing nickel sulfate, cobalt sulfate, and manganese sulfate with each other at a molar ratio of 90:5:5, and an aqueous metal salt solution for forming a surface portion was prepared by mixing nickel sulfate, cobalt sulfate, and manganese sulfate with each other at a molar ratio of 55:15:30. The aqueous metal salt solution for forming the core portion was provided into the reactor to form a core, and then, the aqueous metal salt solution for forming the surface portion and the aqueous metal salt solution for forming the core portion were supplied at a rate of 0.3 liter/hour in the reactor while gradually changing a mixing ratio thereof. As a result, an active material precursor was manufactured to include the core having a constant concentration and a shell having a concentration gradient.
To manufacture a compound in which Mn, Ni and Co have a concentration fixed from a center to a surface, a decreasing concentration and an increasing concentration, respectively, an aqueous metal salt solution (2.4 M concentration) for forming a core portion was prepared by mixing nickel sulfate and manganese sulfate with each other at a molar ratio of 75:25, and an aqueous metal salt solution for forming a surface portion was prepared by mixing nickel sulfate, cobalt sulfate, and manganese sulfate with each other at a molar ratio of 55:20:25. The same method as described in the manufacture example 2, except for these features of the present example, was performed to manufacture an active material precursor.
A shell having a concentration gradient and a certain thickness was formed using nickel sulfate, cobalt sulfate, and manganese sulfate mixed at a molar ratio of 98:00:02 as an aqueous metal salt solution for forming a core portion and using nickel sulfate, cobalt sulfate, and manganese sulfate mixed at a molar ratio of 85:05:10 as an aqueous metal salt solution for forming a surface portion, and then, a shell having a certain thickness was also formed using a solution obtained by mixing nickel sulfate, cobalt sulfate, and manganese sulfate mixed with each other at a molar ratio of 65:10:25. Thus, two gradients in concentration were formed in the shell. The same method as described in the manufacture example 1, except for these features of the present example, was performed to manufacture an active material precursor.
A solution obtained by mixing nickel sulfate, cobalt sulfate, and manganese sulfate at a molar ratio of 80:10:10 was used as an aqueous metal salt solution for forming a core portion, and a solution obtained by mixing nickel sulfate, cobalt sulfate, and manganese sulfate at a molar ratio of 50:20:30 was used as an aqueous metal salt solution for forming a surface portion. The same method as in the manufacture example 1, except for these features of the present example, was performed to manufacture an active material precursor.
A solution obtained by mixing nickel sulfate, cobalt sulfate, and manganese sulfate at a molar ratio of 85:05:10 was used as an aqueous metal salt solution for forming a core portion, and a solution obtained by mixing nickel sulfate, cobalt sulfate, and manganese sulfate at a molar ratio of 60:15:25 was used as an aqueous metal salt solution for forming a surface portion. The same method as in the manufacture example 2, except for these features of the present example, was performed to manufacture an active material precursor.
A solution obtained by mixing nickel sulfate, cobalt sulfate, and manganese sulfate at a molar ratio of 90:00:10 was used as an aqueous metal salt solution for forming a core portion, and a solution obtained by mixing nickel sulfate, cobalt sulfate, and manganese sulfate at a molar ratio of 54:15:31 was used as an aqueous metal salt solution for forming a surface portion. The same method as in the manufacture example 3, except for these features of the present example, was performed to manufacture an active material precursor.
A shell having a concentration gradient and a certain thickness was formed using nickel sulfate, cobalt sulfate, and manganese sulfate mixed at a molar ratio of 96:00:04 as an aqueous metal salt solution for forming a core portion and using nickel sulfate, cobalt sulfate, and manganese sulfate mixed at a molar ratio of 80:05:15 as an aqueous metal salt solution for forming a surface portion, and then, a shell having a certain thickness was also formed using a solution obtained by mixing nickel sulfate, cobalt sulfate, and manganese sulfate mixed with each other at a molar ratio of 55:15:30. Thus, two gradients in concentration were formed in the shell. The same method as described in the manufacture example 1, except for these features of the present example, was performed to manufacture an active material precursor.
A shell having a concentration gradient and a certain thickness was formed using nickel sulfate, cobalt sulfate, and manganese sulfate mixed at a molar ratio of 95:02:03 as an aqueous metal salt solution for forming a core portion and using nickel sulfate, cobalt sulfate, and manganese sulfate mixed at a molar ratio of 90:04:06 as an aqueous metal salt solution for forming a surface portion, and then, a shell having a certain thickness was also formed using a solution obtained by mixing nickel sulfate, cobalt sulfate, and manganese sulfate mixed with each other at a molar ratio of 67:09:24. Thus, two gradients in concentration were formed in the shell. The same method as described in the manufacture example 1, except for these features of the present example, was performed to manufacture an active material precursor.
(NH4)2HPO4 was synthesized in a 4 liter continuous stirred-tank reactor (CSTR) under a condition of pH 5 and then was pulverized using a planetary mill to obtain nanometer-sized particles.
The obtained nano-particles of 0.25 wt % was mixed with LiNO3 (as lithium salt) and the cathode active material precursor (99.75 wt %) of each of the manufacture examples 1 to 4. A dry ball milling coating process was performed on each of these mixtures at a speed of 100 rpm for 12 hours. At this time, a used container had a volume of 50 ml, and zirconia balls were used. The used zirconia balls had one ball of a diameter of 10 mm and three balls of a diameter of 5 mm. The cathode active materials coated with the nano-particles were thermally treated at 500° C. for 5 hours in an air atmosphere to manufacture cathode active materials coated with PO4 of embodiments 1 to 4.
Cathode active materials coated with PO4 of embodiments 5 to 8 were manufactured by the same method as the embodiments 1 to 4 except for using NH4PO4 as a coating precursor and using the active material precursors of the manufacture examples 5 to 8.
Cathode active materials coated with PO4 of embodiments 9 to 12 were manufactured by the same method as the embodiments 1 to 4 except for using H3PO4 as a coating precursor and using the active material precursors of the manufacture examples 1, 6, 3 and 8.
Cathode active materials used as comparison examples 1 to 9 were manufactured by the same method as the embodiment 1 except for not using a coating precursor but using the active material precursors of the manufacture examples 1 to 9
XRD measurement was performed to the cathode active materials manufactured in the embodiment 3 and the comparison example 3, and the results were shown in
The cathode active material of each of the embodiments 1 to 12 and the comparison examples 1 to 9, super P used as a conductive material, and polyvinylidene fluoride (PVdF) used as a binder were mixed with each other at a weight ratio of 85:7.5:7.5 to form slurry.
The slurry was uniformly coated on aluminum foil having a thickness of 20 μm, and then, the aluminum foil coated with the slurry was vacuum-dried at 120° C. to manufacture a cathode. A coin cell was manufactured using the manufactured cathode by a known method. At this time, lithium foil was used as an electrode opposite to the cathode, and a porous polyethylene layer (Celgard, LLC, No. Celgard 2300, a thickness: 25 μm) was used as a separator. In addition, the coin cell used a liquid electrolyte including a mixture solvent and 1.2M LiPF6 dissolved in the mixture solvent. The mixture solvent was obtained by mixing ethylene carbonate and ethylmethyl carbonate with each other at a volume ratio of 3:7.
A charge/discharge test and a cycle life test were performed on the cells manufactured using the cathode active materials of the embodiments 1 to 12 and the comparison 1 to 8, and measured results were shown in
The charge/discharge test was performed to each of the samples 10 times between 2.7V and 4.5V under a condition of 0.1 C, and an average value was taken from the measured values. The cycle life test was performed to each of the samples 60 times or more between 2.7V and 4.5V under conditions of 0.5 C and 25° C.
As shown in
In a state that the cathode including each of the cathode active materials of the embodiments 1 to 12 and the comparison examples 1 to 8 was charged to 4.3V, the cathode was measured by a differential scanning calorimetry (DSC) analyzer while raising temperature at a rate of 10° C./min. The measured results were shown in
As shown in
100 ml distilled water was mixed with the active material (10 g) of each of the embodiments 1 to 12 and the comparison 1 to 8, and then, the distilled water was filtered. The filtered distilled water of 50 ml was provided into a T50 apparatus of METLER TOLEDO international Inc., and a 10% aqueous hydrochloric acid solution was added little by little into the T50 apparatus to start titration. Two inflection points occurred after the titration. An added amount of the aqueous hydrochloric acid solution at the inflection point was measured to calculate the amount of residual lithium, and the results were shown in the following table 3.
Zirconium acetatehydroxide ((CH3CO2)xZr(OH)y, x+y=4), ZAH) was synthesized in a 4 L CSTR under a condition of pH 8 and then was pulverized using a planetary mill to obtain nanometer-sized particles.
The obtained nano-particles of 0.25 wt % was mixed with lithium salts (LiOH and Li2CO3) and the cathode active material precursor (99.75 wt %) of each of the manufacture examples 5, 2, 7, and 4. A dry ball milling coating process was performed on each of these mixtures at a speed of 100 rpm for 12 hours. At this time, a used container had a volume of 50 ml, and zirconia balls were used. The used zirconia balls had one ball of a diameter of 10 mm and three balls of a diameter of 5 mm. The cathode active materials coated with the nano-particles were thermally treated at 500° C. for 5 hours in an air atmosphere to manufacture cathode active materials coated with ZrO2 of embodiments 13 to 16.
A cathode active material was manufactured by the same method as the embodiment 15 except for mixing the obtained nano-particles of 0.50 wt % with the cathode active material precursor (99.50 wt %) of the manufacture example 7.
A cathode active material was manufactured by the same method as the embodiment 15 except for mixing the obtained nano-particles of 0.75 wt % with the cathode active material precursor (99.25 wt %) of the manufacture example 7.
A cathode active material was manufactured by the same method as the embodiment 15 except for mixing the obtained nano-particles of 1.00 wt % with the cathode active material precursor (99.00 wt %) of the manufacture example 7.
XRD measurement was performed to the cathode active materials manufactured in the embodiment 16 and the comparison example 4, and the results were shown in
Cell characteristics of the embodiments 15 and 15-2 to 15-4 were measured, and the measured results were shown in
A charge/discharge test and a cycle life test were performed on a cell using each of the cathode active materials of the embodiments 13 to 16, and measured results were shown in
The residual lithium amounts of the cathode active materials of the embodiments 13 to 16 were calculated using the same method as the experimental example 1-4, and the results were shown in the following table 6.
Cathode active materials coated with SeO3 of embodiments 17 and 18 were manufactured by the same method as the embodiment 1 except for using H2SeO3 as a coating precursor and using the active material precursors of the manufacture examples 6 and 9.
XRD measurement was performed to the cathode active materials manufactured in the embodiment 17 and the comparison example 6, and the results were shown in
A charge/discharge test and a cycle life test were performed on a cell using each of the cathode active materials of the embodiments 17 and 18 and the comparison example 9, and measured results were shown in
The residual lithium amounts of the cathode active materials of the embodiments 17 and 18 and the comparison example 9 were calculated using the same method as the experimental example 1-4, and the results were shown in the following table 8.
Cathode active materials coated with SnO2 of embodiments 19 and 20 were manufactured by the same method as the embodiment 1 except for using H2SnO3 as a coating precursor and using the active material precursors of the manufacture examples 7 and 9.
A charge/discharge test and a cycle life test were performed on a cell using each of the cathode active materials of the embodiments 19 and 20, and measured results were shown in
The residual lithium amounts of the cathode active materials of the embodiments 19 and 20 and the comparison examples 6 and 9 were calculated using the same method as the experimental example 1-4, and the results were shown in the following table 10.
(NH4)2HPO4 was synthesized in a 4 L CSTR under a condition of pH 5 and then was pulverized using a planetary mill to obtain nanometer-sized particles.
Each of the active material precursors of the manufacture examples 1 and 3 and lithium hydroxide (LiOH) were mixed with each other at a molar ratio of 1.0:1.19, and then, a preliminary baking process was performed on the mixture. In the preliminary baking process, the mixture was heated at a heating rate of 2° C./min and was maintained at a temperature of 280° C. for 5 hours. Thereafter, the mixture was baked at a temperature of 900° C. for 10 hours to manufacture a cathode active material.
The obtained nano-particles of 0.25 wt % was mixed with the manufactured cathode active material of 99.75 wt % in a solvent (distilled water, methanol, or ethanol), and a wet coating process was performed at a speed 100 rpm for 12 hours. The cathode active materials coated with the nano-particles were thermally treated at 500° C. for 5 hours in an air atmosphere to manufacture cathode active materials coated with PO4 of embodiments 21 and 22.
Cathode active materials coated with PO4 of embodiments 23 and 24 were manufactured by the same method as the embodiment 21 except for using NH4PO4 as a coating precursor and using the active material precursors of the manufacture examples 6 and 9.
Cathode active materials coated with PO4 of embodiments 25 and 26 were manufactured by the same method as the embodiment 21 except for using H3PO4 as a coating precursor and using the active material precursors of the manufacture examples 7 and 9.
A charge/discharge test and a cycle life test were performed on a cell using each of the cathode active materials of the embodiments 21 to 26, and measured results were shown in
The residual lithium amounts of the cathode active materials of the embodiments 21 to 26 were calculated using the same method as the experimental example 1-4, and the results were shown in the following table 12.
Cathode active materials coated with SeO3 of embodiments 27 and 28 were manufactured by the same method as the embodiment 21 except for using H2SeO3 as a coating precursor and using the active material precursors of the manufacture examples 1 and 9.
A charge/discharge test and a cycle life test were performed on a cell using each of the cathode active materials of the embodiments 27 and 28, and measured results were shown in
In a state that the cathode including each of the cathode active materials of the embodiments 27 and 28 and the comparison example 9 was charged to 4.3V, the cathode was measured by a DSC analyzer while raising temperature at a rate of 10° C./min. The measured results were shown in
The residual lithium amounts of the cathode active materials of the embodiments 27 and 28 were calculated using the same method as the experimental example 1-4, and the results were shown in the following table 15.
Cathode active materials coated with SnO2 of embodiments 29 and 30 were manufactured by the same method as the embodiment 21 except for using H2SnO3 as a coating precursor and using the active material precursors of the manufacture examples 6 and 3.
A charge/discharge test and a cycle life test were performed on a cell using each of the cathode active materials of the embodiments 29 and 30, and measured results were shown in
The residual lithium amounts of the cathode active materials of the embodiments 29 and 30 were calculated using the same method as the experimental example 1-4, and the results were shown in the following table 17.
The cathode active material of the present invention includes at least one coating layer which includes an oxide of a coating element and is formed on the surface of the cathode active material, and thus, the stability and electrical conductivity of the cathode active material are improved. In addition, the battery including cathode active material has excellent charge/discharge and cycle life characteristics and excellent thermal stability.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2013-0011138 | Jan 2013 | KR | national |
| 10-2014-0012313 | Feb 2014 | KR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2014/000925 | 2/3/2014 | WO | 00 |
