The present disclosure relates to the technical field of cathode materials for lithium-ion battery, particularly to a cathode material, a preparation method and a use thereof, and a lithium-ion battery.
More and more clean energy has been applied on the electrical devices and power equipments in response to the world-wide urgent pursuit of new energy at present. Since the Sony Corporation pioneered to launch the lithium-ion battery in the 1990s, the lithium-ion battery has attracted wide-spread attention from numerous energy storage device manufactures and the research community due to its prominent advantages such as high specific energy and recyclability. The cathode materials for lithium-ion battery have undergone the evolutions of LiCoO2, Li2MnO4 and LiFePO4 and the like, the current development goal is mainly focused on the ternary materials.
China has imposed increasingly higher requirements on the endurance mileage and safety of the electric vehicles, the research community has implemented intense and in-depth investigation and research on the high nickel materials in said ternary materials. Among them, the direct effect of a pore diameter of the cathode material at the surface and interior on the material properties is becoming more apparent. When the pore diameter is larger and the more pores are presented, it directly reflects the porosity degree of the material surface and inside, it provide sufficient interfaces for the immersion of the electrolyte and the deintercalation of lithium ions during the charging and discharging process, thereby effectively increasing the actual capacity and the endurance mileage after a single charging process of the cathode material used in a battery. However, if the pore diameter is larger and the more pores are presented, it is prone to cause collapse of the surface crystal structure during the lithium ion deintercalation process, thereby decreasing the actual service life of the battery. Therefore, it is very important to effectively control the most appropriate pore distribution in the particles, especially the pore size and the number of pores during the process of preparing the cathode material.
CN108123119A discloses a nickel-based active material for lithium secondary battery, wherein a porosity of an exterior portion of the secondary particle may be within a range of 6-20%, a porosity of an interior portion of the secondary particle may be 5%. The prior art comprises a cathode material having an exterior porosity more than interior porosity, while in practical use, the electrolyte is immersed the surface of material in a short time, and the porous exterior structure can increase the initial capacity, however, the surface may easily collapse during the process of charging and discharging for many times, causing an irreversible existence of “dead lithium”, the interior structure is relatively dense, and the capacity will significantly decrease during the later stage of charging and discharging process, such a situation is undesired for the industrial practitioners.
The present disclosure intends to overcome the problem in the prior art that the short-term and long-term properties of a lithium-ion battery in the charging and discharging can hardly balanced, and provides a cathode material and a preparation method and a use thereof; the cathode material has a specific pore diameter, pore diameter distribution, pore diameter area and microcrystallite structure, so that both the short-term properties such as initial charge-discharge capacity and long-term properties such as capacity retention ratio of a lithium ion battery prepared with the cathode material can be improved during the charge-discharge process.
In order to achieve the above objects, a first aspect of the present disclosure provides a cathode material, wherein the cathode material is composed of secondary particles formed by agglomeration of primary particles; and
A second aspect of the present disclosure provides a method for preparing a cathode material comprising:
A third aspect of the present disclosure provides a cathode material prepared by the aforementioned method.
A fourth aspect the present disclosure provides a use of the aforementioned cathode material in a lithium-ion battery.
Due to the above-mentioned technical scheme, the cathode material and the method and use thereof provided by the present disclosure produce the following favorable effects:
Further, a suitable pore diameter distribution of the cell material can be achieved in the method for preparing the cathode material provided by the present disclosure, by controlling the pH at various phases during the co-precipitation reaction to obtain a suitable precursor, and subsequently controlling the doping and sintering process and the cladding and post-treatment process in the later stage, thereby ensuring the desirable performance for the short-term and long-term properties of a lithium ion battery prepared with the cathode material.
The terminals and any value of the ranges disclosed herein are not limited to the precise ranges or values, such ranges or values shall be comprehended as comprising the values adjacent to the ranges or values. As for numerical ranges, the endpoint values of the various ranges, the endpoint values and the individual point value of the various ranges, and the individual point values may be combined with one another to produce one or more new numerical ranges, which should be deemed have been specifically disclosed herein.
A first aspect of the present disclosure provides a cathode material, wherein the cathode material is composed of secondary particles formed by agglomeration of primary particles; and
In the present disclosure, d10 refers to a pore diameter that the cumulative particle distribution is 10% after the average pore diameters d of the cathode material obtained from BJH are arranged from small to large; d50 refers to a pore diameter that the cumulative particle distribution is 50% after the average pore diameters d of the cathode material obtained from BJH are arranged from small to large; d90 refers to a pore diameter that the cumulative particle distribution is 90% after the average pore diameters d of the cathode material obtained from BJH are arranged from small to large.
In the present disclosure, a cathode material having the above-described specific pore diameter and pore diameter distribution enables that both the short-term properties such as initial charge-discharge capacity and long-term properties such as capacity retention ratio of a lithium ion battery prepared with the cathode material can be improved during the charge-discharge process.
In the present disclosure, the cathode material having the above-mentioned pore diameter d50 exhibits excellent initial charge-discharge capacity and cycle performance. Specifically, when the pore diameter d50 is less than 10 nm, the internal pore diameter is small, the Li ions in the cathode material are confronted with multiple barriers when shuttling back and forth, which is unfavorable for exertion of the entire capacity of the material. When d50 is greater than 40 nm, the internal pore diameter is large, the grain strength of the material is weakened, the grain breakage and pulverization would easily occur when a positive electrode of the battery is rolled.
In the present disclosure, the cathode material having the above-mentioned pore diameter d90 exhibits excellent initial charge-discharge capacity and cycle performance. Specifically, when k90 is less than 1, the pore diameter distribution is close to uniformity, which is quite difficult in practical production; when k90 is greater than 8, the pore sizes are not uniformly dispersed in the material, and the degree of infiltration of the electrolyte is different, which leads to different charge and discharge depths, such that the cycle performance finally deteriorates.
Further, the pore diameters d10, d50 and d90 of the secondary particles obtained by BJH satisfy the following relationship: 12 nm≤d50≤35 nm; 2≤k90≤6.
According to the present disclosure, a ratio γ of an area SII of pore diameters of average sizes of the secondary particles to an average area SI of the primary particles satisfies the following relationship: 0.01%≤γ≤0.2%.
In the present disclosure, the area of pore diameters of average sizes of the secondary particles refers to an area which is calculated based on an average value of the pore diameters.
In the present disclosure, the area SII of pore diameters of average sizes of the secondary particles is calculated according to the following Formula: SII=π(d50/2)2; an average area SI of the primary particles is calculated according to the following Formula: SI=a×b, wherein a denotes the length of long axis of primary particles, and b denotes the length of short axis of primary particles, the parameters a and b are derived from the Scanning Electron Microscopy (SEM) graph of primary particles; in particular, selecting at least 10 primary particles from a cross-section of cathode material, obtaining the length of long axis and the length of short axis of primary particles, and calculating an average value of the areas of at least 10 primary particles, which is exactly the SI.
In the present disclosure, when the ratio γ of an area SII of pore diameters of average sizes of the secondary particles to an average area SI of the primary particles satisfies the above relationship, the effect of pores can be exerted at a maximum, and the performance of capacity is not affected, so that the battery fabricated with the cathode material simultaneously has high initial charge-discharge capacity and excellent cycle performance.
Further, the ratio γ of an area SII of pore diameters of average sizes of the secondary particles to an average area SI of the primary particles satisfies the following relationship: 0.05%≤γ≤0.20%.
According to the present disclosure, an intensity I103 of the (003) crystallographic plane and a peak intensity I104 of the (104) crystallographic plane of the cathode material obtained by XRD satisfy the following relationship: 1≤I003/I104≤1.8.
In the present disclosure, the intensity I103 of the (003) crystallographic plane and the peak intensity I104 of the (104) crystallographic plane of the cathode material obtained by XRD are obtained by using an XRD diffractometer, through a step scan and a small angle test method.
In the present disclosure, when the an intensity I103 of the (003) crystallographic plane and the peak intensity I104 of the (104) crystallographic plane of the cathode material obtained by XRD satisfy the aforementioned relationship, it indicates that the microcrystalline structure of the cathode material has a desirable lamellar structure, which causing that the cathode material is more conducive to the deintercalation of lithium ions during the charging and discharging cycles, thereby improving properties of the lithium-ion battery fabricated with the cathode material.
Further, an intensity I103 of the (003) crystallographic plane obtained by XRD and a peak intensity I104 of the (104) crystallographic plane satisfy the following relationship: 1.1≤I003/I104≤1.7.
According to the present disclosure, an interlayer spacing d003 of the (003) crystallographic plane and an interlayer spacing d104 of the (104) crystallographic plane of the cathode material obtained by XRD satisfy the following relationship: d003/d104≥1.
In the present disclosure, the interlayer spacing d003 of the (003) crystallographic plane and the interlayer spacing d104 of the (104) crystallographic plane of the cathode material obtained by XRD are calculated based on the Scherrer Equation or Debye-Scherrer Equation: d=kλ/(β cos θ).
In the present disclosure, when the interlayer spacing d003 of the (003) crystallographic plane and the interlayer spacing d104 of the (104) crystallographic plane of the cathode material obtained by XRD satisfy the aforementioned relationship, it can ensure that the material has an appropriate contact area and angle when contacting with the electrolyte, so that the capacity and cycle performance and other property of the final material are effectively improved.
Further, an interlayer spacing d003 of the (003) crystallographic plane and an interlayer spacing d104 of the (104) crystallographic plane of the cathode material obtained by XRD satisfy the following relationship: 1.2≤d003/d104≤3.
According to the present disclosure, the grain diameters D5, D50 and D95 of the cathode material satisfy the following relationship:
5 μm≤D50≤20 μm; 0.5≤K95≤2, wherein K95=(D95−D5)/D50.
In the present disclosure, the grain diameter D50 of the cathode material shall fall into the above range; if the D50 of the cathode material is less than 5 μm, the mobility of particles is poor, thus the requirements on humidity and temperature of the environment during the preparation of cathode material and the fabrication of the battery cell are high. If the D50 of the cathode material is larger than 20 μm, when the cathode material is used for the fabrication of a battery cell, the capacity of said battery cell cannot be sufficiently exerted, and the particles of the cathode material are easily crushed during the rolling process of the battery.
In the present disclosure, the grain diameters D5, D50 and D95 of the cathode material are measured by a laser particle size analyzer.
Further, 8 μm≤D50≤15 μm; 0.6≤K95≤1.8.
According to the present disclosure, a particle strength MCT of the cathode material satisfies the following relationship: 60 MPa≤MCT≤200 MPa.
In the present disclosure, when the particle strength MCT of the cathode material satisfies the above range, the material has an appropriate strength. If the particle strength MCT is less than 60 MPa, the particles can be easily crushed during the fabrication process of the pole piece of battery. If the particle strength MCT is greater than 200 MPa, it also prevents the deintercalation of lithium ions. Only when the particle strength of the cathode material falls into the above range, the comprehensive performance of the material can be enhanced.
In the present disclosure, the particle strength MCT of the cathode material is measured by a miniature compression test machine.
Further, 80 MPa≤MCT≤180 MPa.
According to the present disclosure, the BET of the cathode material satisfies the following relationship: 0.25 m2/g≤BET≤0.95 m2/g.
In the present disclosure, when the specific surface area BET of the cathode material falls into the above range, the pores on a surface of the cathode material effectively increase the contact area when the material is in contact with the electrolyte, effectively enhancing the exertion of the first charge and discharge capacity of the material; however, if the specific surface area BET of the cathode material is excessively high and the pores on the surface is too much, the surface crystal structure is prone to collapse during the long charge and discharge cycles, thereby causing rapid attenuation of the reversible capacity. Therefore, an appropriate BET ensures that the comprehensive performance of the material can be improved.
Further, 0.3 m2/g≤BET≤0.85 m2/g.
According to the present disclosure, the cathode material has a composition as shown in Formula I:
Lie(Ni1-x-y-z-mCoxMyGzHm)O2 Formula I;
In the present disclosure, the cathode material comprises a doping element G and a cladding element H, and the specific kinds of doping element G and cladding element H are selected so as to form a different bonding between the transition metal and various doping and cladding elements in the cathode material; in particular, after treating with appropriate process conditions, the battery fabricated with the cathode material has a high initial charge-discharge capacity and excellent cycle performance.
Further, 0.95≤e≤1.1, 0.53≤1−x−y−z−m<0.99, 0<y<0.15, 0<z<0.03, 0<m<0.03.
Further, M is Mn; G is at least one element selected from the group consisting of Al, Mg, Ca, Sr, Zr, Nb and Mo; and H is at least one element selected from the group consisting of B, Zr, Nb, Al and Y.
The method for preparing a cathode material used in the present disclosure comprises a design of continuously varying the pH during the process of preparing a precursor; in particular, the pH varies within a range of 10-13.
The method for preparing a cathode material used in the present disclosure further comprises a design in regard to a sintering temperature and a sintering time during the sintering process, wherein the sintering temperature is 650-900° C. and the sintering time is 6-30 h.
The method for preparing a cathode material used in the present disclosure further comprises a design in regard to a treatment temperature and a treatment time during the surface heat treatment process, wherein the heat treatment temperature is within a range of 200-500° C., and the heat treatment time is within a range of 5-18 h.
A second aspect of the present disclosure provides a method for preparing a cathode material comprising:
The method for preparing the cathode material used in the present disclosure comprises a design of continuously varying the pH during the preparation process of precursor material; in particular, the pH is varied within a range of 10-13. A suitable pore diameter distribution of the cell material can be achieved, by controlling the pH at various phases during the co-precipitation reaction to obtain a suitable precursor, and subsequently controlling the doping and sintering process and the cladding and post-treatment process in the later stage, thereby ensuring the desirable performance for the short-term and long-term properties of a lithium ion battery prepared with the cathode material.
According to the present disclosure, the nickel salt is at least one selected from the group consisting of nickel sulfate, nickel nitrate and nickel chloride; the cobalt salt is at least one selected from the group consisting of cobalt sulfate, cobalt nitrate and cobalt chloride; the M salt is selected from Al salt and/or Mn salt, more preferably, the Al salt is at least one selected from the group consisting of aluminium sulphate, aluminium nitrate and aluminium chloride, and the Mn salt is at least one selected from the group consisting of manganese sulphate, manganese nitrate and manganese chloride. The precipitating agent is an alkaline solution, such as a sodium hydroxide solution; the complexing agent is aqueous ammonia.
According to the present disclosure, 10 h≤t≤120 h, preferably 15 h≤t≤100 h.
According to the present disclosure, the temperature of co-precipitation reaction is within a range of 30-100° C., more preferably within a range of 40-70° C.
Further, in order to further provide the cathode material with the specific pore diameter distribution and pore size, the suitable grain diameter and particle strength and other characteristics, the Q1, Q2 and Q3 are decremented in an arithmetic progression.
According to the present disclosure, the co-precipitation reaction is performed in the presence of nitrogen gas and/or oxygen gas.
Further, when the co-precipitation reaction is performed during the 0-t/3 phase, the co-precipitation reaction is performed in the presence of nitrogen gas and oxygen gas, the volume fraction of oxygen gas is 0-5 vol %, based on the total volume of nitrogen gas and oxygen gas; when the co-precipitation reaction is performed during the t/3-2/3t phase, the co-precipitation reaction is performed in the presence of nitrogen gas and oxygen gas, the volume fraction of oxygen is 0-3 vol %, based on the total volume of nitrogen gas and oxygen gas; when the co-precipitation reaction is performed during the 2/3t-t phase, the co-precipitation reaction is performed in the presence of nitrogen gas.
In the present disclosure, the precursors with a specific structure and pore diameter can be obtained by arranging that the co-precipitation reaction is performed in the presence of oxygen gas during the 0-t/3 phase and t/3-2/3t phase, and the volume fraction of oxygen is respectively controlled within the above-mentioned ranges.
Still further, the 0-t/3 phase of the co-precipitation reaction has a volume fraction of oxygen gas within a range of 0-3 vol % based on the total volume of nitrogen gas and oxygen gas, and the t/3-2/3t phase of the co-precipitation reaction has a volume fraction of oxygen gas within a range of 0-2 vol % based on the total volume of nitrogen gas and oxygen gas.
In the present disclosure, the cathode material precursor has a composition as shown in Formula II:
(Ni1-x-yCoxMy)(OH)2 Formula II;
According to the present disclosure, the Li source is added in an amount such that 0.9≤[n(Li)]/[n(Ni)+n(Co)+n(M)]≤1.3.
Further, the Li source is added in an amount such that 0.95≤[n(Li)]/[n(Ni)+n(Co)+n(M)]≤1.2.
In the present disclosure, the doping element G can be introduced in step (2) of the co-precipitation reaction process or in step (3) of the sintering process, the present disclosure does not impose particular definition for the addition amount of the doping element G solution in step (2) and/or the addition amount of the doping element G in step (3), so long as the doping element G is used in an amount of 5,000 ppm or less, based on the total weight of the cathode material precursor. The method of the present disclosure includes the designing of the doping element and the sintering temperature and sintering time in the sintering process, wherein the sintering temperature is within a range of 650-900° C., and the sintering time is within a range of 6-30 h.
The sintering conditions comprise: a sintering temperature of 650-900° C.; and a sintering time of 6-30 h.
According to the present disclosure, the doping element G is at least one element selected from groups IIA-IIIA of the periods 2-5.
In the present disclosure, the growth of primary particles can be further controlled by controlling the type of the doping element G and the sintering conditions, especially the sintering temperature, in order to control the average area of the primary particles, such that the area of average pore diameter and the area of the primary particles of the prepared cathode material satisfy the definitions of the present disclosure, thereby maximizing the functions of pores without affecting the exertion of battery capacity. Specifically, a use of the particular type of the aforementioned doping element G can form a material which can increase the crystal particles during the reaction, control the growth direction and the crystal planes, so as to control a ratio of the major diameter to the minor diameter of the crystal particles, and control the interfacial contact and pores between the crystal particles. By controlling the content of the doping element G and the sintering temperature to be within the aforementioned ranges, the porosity on a surface of the cathode material can be reduced, and the residual alkali on a surface of the cathode material can be controlled.
Further, the added amounts of the doping element G solution and the doping element G cause that the doping element G is used in an amount of 0-3,000 ppm, based on the total weight of the cathode material precursor.
Further, the sintering conditions comprise: a sintering temperature of 700-890° C.; and a sintering time of 8-25 h.
Further, the doping element G is at least one element selected from the group consisting of Al, Mg, Ca, Sr, Zr, Nb and Mo.
The method used in the present disclosure comprises the designs in regard to the cladding element in a surface heat treatment process and the treatment temperature and treatment time in a heat treatment process, wherein the heat treatment temperature is within a range of 200-500° C., and the heat treatment time is within a range of 5-18 h. The cladding element H is used in an amount of 5,000 ppm or less, based on the total weight of the first sintered material.
In the present disclosure, when the used amount of the cladding element H satisfies the above-mentioned range, the transition metal and the surface doping element can be bonded with each other to stabilize the crystal structure, and ensure that a proper amount of addition does not block the intercalation and deintercalation of the lithium ions on a surface of the material, thereby effectively ensuring an exertion of the first charge-discharge capacity of the material.
Further, the cladding element H is used in an amount of 0-3000 ppm, based on the total weight of the first sintered material.
According to the present disclosure, the cladding element H is at least one element selected from the group consisting of B, Mg, Ca, Sr, Y, Ti, V, Cr, Fe, Cu, Zr, W, Nb and Al.
According to the present disclosure, a use of the special type elements as the cladding element H enables that the cladding element further reacts with the residual alkali on a surface to generate a lithium metal oxide and form a cladding layer on the material surface, in order to stabilize the structure of the material surface and improve the cycle performance.
Further, the cladding element H is at least one element selected from the group consisting of B, Al, Zr, Nb and Y.
According to the present disclosure, the heat treatment conditions comprises: a heat treatment temperature of 300-500° C.; and a heat treatment time of 5-18 h.
In the present disclosure, the heat treatment performed under the above-mentioned specific conditions can enable that the material only react with the residual alkali on the surface without further entering the crystal lattice and without forming an internal crystal structure that blocks the shuttling of lithium ions, merely form a thin cladding layer on a surface of the material, thereby effectively improving the cycle performance without reducing capacity of the material.
Further, the heat treatment conditions comprise: a heat treatment temperature of 300-480° C.; and a heat treatment time of 5-12 h.
A third aspect of the present disclosure provides a cathode material prepared by the aforementioned method.
According to the present disclosure, the cathode material is composed of secondary particles formed by agglomeration of primary particles;
According to the present disclosure, a ratio γ of an area SII of pore diameters of average sizes of the secondary particles to an average area SI of the primary particles satisfying the following relationship: 0.01%≤γ≤0.2%.
According to the present disclosure, an intensity I103 of the (003) crystallographic plane and a peak intensity I104 of the (104) crystallographic plane of the cathode material obtained by XRD satisfying the following relationship: 1≤I003/I104≤1.8.
According to the present disclosure, an interlayer spacing d003 of the (003) crystallographic plane and an interlayer spacing d104 of the (104) crystallographic plane of the cathode material obtained by XRD satisfy the following relationship: d003/d104≥1.
According to the present disclosure, the grain diameters D5, D50 and D95 of the cathode material satisfy the following relationship:
5 μm≤D50≤20 μm; 0.5≤K95≤2, wherein K95=(D95−D5)/D50.
According to the present disclosure, a particle strength MCT of the cathode material satisfies the following relationship: 60 MPa≤MCT≤200 MPa.
According to the present disclosure, the BET of the cathode material satisfies the following relationship: 0.25 m2/g≤BET≤0.95 m2/g.
According to the present disclosure, the cathode material has a composition as shown in Formula I:
Lie(Ni1-x-y-z-mCoxMyGzHm)O2 Formula I;
A fourth aspect the present disclosure provides a use of the aforementioned cathode material in a lithium-ion battery.
The present disclosure will be described in detail below with reference to examples.
(1) X-Ray Diffraction Test
The samples were measured with an XRD diffractometer (SmartLab 9 KV) using a Cu Ka radiation source through a step scan and a small angle test method. The measurement results comprised diffraction diagrams of (003) peak and (104) peak. The glass sample holder was first loaded with excessive amount of materials, the surface was slightly pressed and scratched with a LED lamp, the parameters were set, the test category was selected, and the BB light path adjustment was performed. The cabin door was opened, the sample was placed on the sample table, the “Execute” button was clicked for carrying out the test, the data was saved, the test was completed.
(2) BET and Pore Diameter Distribution Test
The test was carried out using a Tri-star 3020 specific surface analyzer, 3 g of sample was weighted, and the sample tube was mounted on a vacuum connector at the de-aeration station port. The heating temperature was set at 300° C. and the de-aeration time was set at 120 min. After de-aeration was completed, the sample tube was cooled down. The mass of an empty sample tube and the mass of de-aerated sample and sample tube were input the tester software interface, and the output of the surface area data calculated by the software (BET method and BJH pore diameter test method) were recorded, the test of specific surface area and pore diameter distribution of the cathode material sample was accomplished.
(3) Particle Size Test
The test was carried out using a Mastersizer2000 laser particle size analyzer. The “sample test time” and a “background test time” in the item “number of tests” in “measurement” in the software were modified to 6 s; a cycle number of the item “measurement cycle” was 3 times, a latency time was 5 s, the option “creating a record of the average results from the measurement” was clicked. Next, the “Start” was clicked to automatically perform the background measurement; after the automatic measurement was completed, 40 mL of sodium pyrophosphate was initially added, a small amount of sample was then added with a medicine spoon, the “Start” was clicked until the light cover degree reached ½ of the 10-20% visual area, three results and an average value were recorded.
(4) MCT Test
The measurement was performed using an MCT-210 miniature compression test machine. The MCT-210 test software was first started, the sample table was clamped at an intermediate position of a squash without sliding, to ensure that a height of the sample table was at least 3 cm below the objective lens; the LED light switch in the host machine was turned on, and the hand wheel at the bottom right position of the host machine was shaken, so as to adjust the height of the sample table to ensure that the image of the sample particles in the CCD image display window was distinct. The “start testing” was clicked to measure the particle diameter, the image of particles prior to the compression was saved; the hand wheel was rotated, the particle apex was moved to the lens focus, the sample table was pushed to right side to underneath the squash, the compression test was started; after completion of compression, the sample table was pushed to left side to underneath the objective lens, the hand wheel was rotated until the image obtained after compression was distinct, the image was saved.
(5) Morphology of Cathode Material
The Morphology of the cathode material was tested using a Scanning Electron Microscope (SEM), the cathode material was first subjected to treatments such as embedding, it was then placed in an ion grinder and subjected to thinning to obtain an ion-milled cross-sectional sample of particles. Finally, the cross-sectional sample was fastened on a SEM sample table for carrying out the SEM analysis.
(6) Battery Performance Testing
The button-type battery was placed for 2 h following the fabrication, after the open circuit voltage was stabilized, the cathode was charged to a cut-off voltage 4.3V with a current density of 0.1C, then charged at a constant voltage for 30 min, subsequently discharged to the cut-off voltage of 3V with the same current density, the charging and discharging process was performed once more with the same manner, the battery in the meanwhile was regarded as the activated battery.
The cycle performance test was as follows: using the activated cell, the capacity retention ratio was measured by performing the charging and discharging process for 50 cycles under a temperature of 45° C. with a current density of 1C (200 mA/g) and a voltage range of 3-4.3V.
Each of the raw materials used in the Examples and Comparative Examples was commercially available.
The cathode materials were prepared according to the method of Example 1, the raw material ratios and specific process conditions were shown in Table 1. The cathode materials A2-A10 were prepared.
The cathode materials were prepared according to the method of Example 1, the raw material ratios and specific process conditions were shown in Table 1. The cathode materials D1-D4 were prepared.
The composition of the cathode materials prepared in the Examples and Comparative Examples was shown in Table 2, the structure and the properties of the cathode material were tested, the testing results were shown in Table 3.
The cathode materials of the Examples and the Comparative Example were used for the preparation of a lithium-ion battery, the specific preparation method was as follows: a composite nickel cobalt manganese multi-element cathode material used for a non-aqueous electrolyte secondary battery, acetylene black and polyvinylidene fluoride (PVDF) were mixed according to a mass ratio of 95:3:2, the mixture was coated on aluminum foil and subjected to a drying process, the coated aluminum foil was subjected to a press-forming process with a pressure of 100 MPa, in order to produce positive electrode having a diameter of 12 mm and a thickness of 120 μm, the positive electrode were placed in a vacuum drying oven and subjected to baking at 120° C. for 12 h.
The Li metal sheet having a diameter of 17 mm and a thickness of 1 mm was used as the negative electrode; the polyethylene porous membrane having a thickness of 25 μm was used as the diaphragm; 1 mol/L of a mixture consisting of LiPF6, ethylene carbonate (EC) and diethyl carbonate (DEC) in an equal amount was used as the electrolyte.
The properties of a lithium-ion battery were tested, the test results were shown in Table 4.
As indicated by Table 2, Table 3 and Table 4, the lithium-ion battery fabricated by using a cathode material of the present disclosure having a specific pore diameter and pore diameter distribution, not only exhibits a high initial charge-discharge capacity, but also has a high capacity retention ratio.
Further, when the cathode material has a specific micro-structure, grain strength and the like, both the initial charge-discharge capacity and capacity retention ratio of the lithium-ion battery can be further improved, so that the comprehensive performance of the battery is further enhanced.
The above content describes in detail the preferred embodiments of the present disclosure, but the present disclosure is not limited thereto. A variety of simple modifications can be made in regard to the technical solutions of the present disclosure within the scope of the technical concept of the present disclosure, including a combination of individual technical features in any other suitable manner, such simple modifications and combinations thereof shall also be regarded as the content disclosed by the present disclosure, each of them falls into the protection scope of the present disclosure.
Number | Date | Country | Kind |
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202111611309.0 | Dec 2021 | CN | national |
The application is a continuation application of International Application No. PCT/CN2022/142015, filed on Dec. 26, 2022, which claims priority to Chinese Application No. 202111611309.0, filed on Dec. 27, 2021, which are incorporated herein by reference as if fully set forth.
Number | Date | Country | |
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Parent | PCT/CN2022/142015 | Dec 2022 | US |
Child | 18357866 | US |