Patent Application
20250015255
The present disclosure belongs to the technical field of production of cathode material of a lithium-ion battery, and in particular, relates to cathode material of a lithium battery and a production process thereof.
In September 2020, China officially set up a green development strategy of “striving to achieve peak of carbon dioxide emissions before 2030 and carbon neutrality before 2060”. Replacing traditional fossil energy with green new energy and reducing carbon dioxide emissions are crucial to achieve “carbon neutrality”. Conventional clean energy includes lithium-ion batteries, hydrogen energy, wind energy, solar energy, nuclear energy, etc. Lithium-ion batteries have been highly commercialized and will contribute a lot to the achievement of the goals of “carbon peaking” and “carbon neutrality”.
Continuous improvement of energy density and power density of lithium-ion batteries is the driving force for the continuous iteration of the lithium battery industry, and the overall performance of a lithium battery system is closely related to the performance of a cathode material. The sintering process directly determines the performance indicators of the cathode material, such as electrochemical properties, physical and chemical properties, so it has attracted much attention. Sintering of a cathode material involves putting a precursor, a lithium source and an additive into a saggar, placing the saggar then in a specific atmosphere, and performing complicated multi-step chemical reactions at a high temperature to produce a cathode material. During the reaction, controlling processing parameters is very important for product consistency, especially a sintering temperature, which directly determines key indicators of a product such as phase composition, crystal size, and crystallinity. During the sintering, an upper layer and a lower layer of heat preservation zone of a roller kiln are typically set to the same sintering temperature. However, in actual operation, since a material to be sintered has been placed inside the saggar, its surface layer and bottom layer are actually heated differently. In fact, during an actual sintering, its surface layer is heated at a higher temperature, resulting in faults between the upper layer and the lower layer of the produced cathode material of a lithium battery, and poor product consistency.
The present disclosure is directed to solve at least one of the technical problems existing in prior art. For this purpose, the present disclosure provides cathode material of a lithium battery and a production process thereof, which can effectively improve the consistency of the produced cathode material of the lithium battery.
The above-mentioned technical objectives of the present disclosure is achieved through the following technical solutions.
A process for producing cathode material of a lithium battery comprises steps of: (1) measuring temperature difference, which comprises loading a material to be sintered into a saggar, placing it in a heat preservation zone of a roller kiln, setting a same sintering temperature t for an upper layer and a lower layer of the heat preservation zone of the roller kiln based on characteristics of the material to be sintered, carrying out sintering under a specific atmosphere, and measuring temperature difference Δt between a surface layer and a bottom layer of the material during the sintering; and (2) second sintering, which comprises loading the material to be sintered into a saggar, placing it in the heat preservation zone of the roller kiln, setting the sintering temperature of the upper layer of the heat preservation zone of the roller kiln to t and the sintering temperature of the lower layer to (t+Δt) based on the temperature difference Δt measured in step (1), and sintering the material to be sintered under the specific atmosphere.
Preferably, in step (1), measuring temperature difference Δt between the surface layer and the bottom layer of the material involves: respectively embedding a temperature-measuring component in the surface layer and the bottom layer of the material to be sintered before the sintering, taking out the temperature-measuring component from pieces of material produced by the sintering after the sintering, and measuring deformation of the temperature-measuring component from initial state thereof to calculate the temperature difference Δt.
Preferably, the temperature-measuring component is previously placed inside a temperature-measuring box, and the temperature-measuring box is respectively embedded in the surface layer and the bottom layer of the material to be sintered.
Preferably, the temperature-measuring box is made from the pieces of material produced by sintering the material to be sintered.
Preferably, the temperature-measuring component is placed inside the temperature-measuring box, leaving a gap from inner walls of the box, wherein the gap has a width of 8%-15% of respective lengths of two mutually perpendicular straight lines passing through the center of the temperature-measuring component.
Further preferably, the temperature-measuring component is placed inside the temperature-measuring box, leaving a gap from inner walls of the box, wherein the gap has a width of 10% of respective lengths of two mutually perpendicular straight lines passing through the center of the temperature-measuring component.
Preferably, in step (2), the sintering temperature of the upper layer of the heat preservation zone of the roller kiln is set to t, and the sintering temperature of the lower layer of the heat preservation zone of the roller kiln is set to (t+Δt+2° C.).
Preferably, the temperature-measuring component is a temperature-measuring block or a temperature-measuring ring.
Preferably, the material to be sintered is one of ternary NCM and LiCoO2.
Preferably, the specific atmosphere is an oxygen-containing atmosphere.
Provided is a cathode material of a lithium battery produced by using the above-mentioned production process.
The present disclosure has the following beneficial effects.
(1) According to the present disclosure, by firstly measuring the temperature difference Δt between a surface layer and a bottom layer of the material during the sintering, and then individually setting temperature for an upper layer and a lower layer of the heat preservation zone of the roller kiln, so that the surface layer and the bottom layer of the material in the saggar are actually heated equally or highly similarly during the sintering, thereby more evenly heating the overall material, avoiding occurrence of faults between the upper layer and the lower layer during the sintering, and ensuring better consistency of the final product.
(2) According to the present disclosure, it is preferable to take advantage of the high thermal conductivity and machinability of sintered cathode material of a lithium battery, cut a piece of material after high-temperature sintering into a temperature-measuring box, put the temperature-measuring block (or ring) in the temperature-measuring box, and embed it into the surface layer and the bottom layer of the material to be sintered respectively for sintering. Because the temperature-measuring block (or ring) does not directly contact with the material and there is a gap left between the temperature-measuring block (or ring) and the inner walls of the temperature-measuring box, it will not affected by a stress generated during the sintering of cathode material, enabling the temperature of the surface layer and the bottom layer of the material during the sintering to be identified by measuring the deformation of the temperature-measuring block (or ring) from its initial state, so as to make a targeted adjustment of kiln parameters, improve the uniformity of the finished product and enhance its consistency.
(3) According to the present disclosure, considering the gap and heat conduction between the temperature-measuring block and inner walls of the temperature-measuring box, the temperature difference between the upper layer and the lower layer of the roller kiln is preferably set to (Δt+2° C.).
101 temperature-measuring box, 102 cover of temperature-measuring box, 103 gap, 104 temperature-measuring block, and 105 temperature-measuring ring.
The present disclosure will be further described below with reference to specific examples.
A process for producing a cathode material of LiNi0.5476Co0.1195Mn0.3286Zr0.0043O2 comprised the following steps:
(1) Measurement of temperature difference: 10000 parts by weight of Ni0.55Co0.12Mn0.33(OH)2 precursor, 4250 parts by weight of lithium carbonate and 36 parts by weight of ZrO2 were well mixed and put into a saggar. At the same time, during saggar-loading, two temperature-measuring boxes 101 containing a temperature-measuring block 104, as shown in
(2) Second sintering: 10000 parts by weight of Ni0.55Co0.12Mn0.33(OH)2 precursor, 4250 parts by weight of lithium carbonate and 36 parts by weight of ZrO2 were well mixed, put into a saggar, and sintered at a high temperature in a roller kiln under an oxygen-containing atmosphere. During the sintering, the temperature of the upper layer of the heat preservation zone of the roller kiln was set to 935° C., and the temperature of the lower layer was set to 941° C. (considering the gap and heat conduction between the temperature-measuring block and the inner walls of the temperature-measuring box, the temperature difference between the upper layer and the lower layer of the roller kiln was set to Δt+2° C.). The holding time of the high-temperature section was 11 h, and the total sintering period was 28 h.
The pieces of material of the surface layer and the bottom layer inside the saggar after second sintering were taken for analysis of microstructure, and respectively prepared into finished products for half-cell test. The test method was to charge cells to 4.35 V first, and then discharge at a rate of 0.1 C with a cut-off voltage of 2.8 V.
Test results: SEM results of the pieces of material of the surface layer and the bottom layer are shown in
A process for producing a cathode material of LiNi0.6438Co0.06933Mn0.2773Zr0.0037Al0.0058O2 comprised the following steps.
(1) Measurement of temperature difference: 10000 parts by weight of Ni0.65Co0.08Mn0.27(OH)2 precursor, 4640 parts by weight of lithium hydroxide, 29 parts by weight of ZrO2, and 19 parts by weight of Al2O3 were well mixed and put into a saggar. During saggar-loading, two temperature-measuring boxes 101 containing a temperature-measuring ring 105, as shown in
(2) Second sintering: 10000 parts by weight of Ni0.65Co0.07Mn0.28(OH)2 precursor, 4640 parts by weight of lithium hydroxide, 29 parts by weight of ZrO2, and 19 parts by weight of Al2O3 were well mixed and put into a saggar and sintered at a high temperature in a roller kiln under an oxygen-containing atmosphere. During the sintering, the temperature of the upper layer of the heat preservation zone of the roller kiln was set to 928° C., and the temperature of the lower layer was set to 934° C. (considering the gap and heat conduction between the temperature-measuring ring and the inner walls of the temperature-measuring box, the temperature difference between the upper layer and the lower layer of the roller kiln was set to Δt+2° C.). The holding time of the high-temperature section was 12 h, and the total sintering period was 30 h.
The pieces of material of the surface layer and the bottom layer inside the saggar after second sintering were taken for analysis of microstructure, and respectively prepared into finished products for half-cell test. The test method was to charge cells to 4.35 V first, and then discharge at a rate of 0.1 C with a cut-off voltage of 2.8 V.
Test results: SEM results of the pieces of material of the surface layer and the bottom layer show that the produced primary particles of materials at the surface layer and the bottom layer are equivalent and show no significant difference. Simultaneously, the half-cell prepared from the material at the upper layer had a capacity per gram of 189 mAh, and the one prepared from the material at the lower layer had a capacity per gram of 189.5 mAh, which were almost at the same level, indicating high consistency of the products.
A process for producing a cathode material of LiNi0.6904Co0.0493Mn0.2466Zr0.0042Al0.0054B0.0042O2 comprised the following steps:
(1) Measurement of temperature difference: 10000 parts by weight of Ni0.70Co0.05Mn0.25(OH)2 precursor, 4780 parts by weight of lithium hydroxide, 36 parts by weight of ZrO2, 19 parts by weight of Al2O3, and 10 parts by weight of B2O3 were well mixed and put into a saggar. During saggar-loading, two temperature-measuring boxes containing temperature-measuring block were separately embedded in a bottom layer and a surface layer of a material. After the temperature-measuring block was placed into the temperature-measuring box, the box was covered with a cover of the temperature-measuring box. 1 row of saggar was fed, and 8 rows of empty saggars were respectively arranged before and after the feeding saggar to keep the temperature even, so as to ensure a temperature of the material to be substantially the same as the temperature of the material while continuously feeding raw materials into the kiln. Then, high-temperature sintering was carried out in an oxygen-containing atmosphere. The temperature-measuring box was made by cutting pieces of sintered LiNi0.6904Co0.0493 Mn0.2466Zr0.0042Al0.0054B0.0042O2 cathode material. The temperature-measuring block was placed into a temperature-measuring box, leaving gaps from inner walls of the box. The width of the gaps was 10% of the respective lengths of two mutually perpendicular straight lines passing through the center of the temperature-measuring block. During the sintering, the temperature of an upper layer and a lower layer of the heat preservation zone of the roller kiln was both set to 923° C. The holding time of the high-temperature section was 10.5 h, and the total sintering period was 26 h. After discharging, the pieces of material were broken apart, to take out the temperature-measuring box and then the temperature-measuring block. According to the shrinkage of the temperature-measuring block, the temperature difference between the surface layer and the bottom layer of the material was quantitatively determined as Δt=5° C.
(2) Second sintering: 10000 parts by weight of Ni0.70Co0.05Mn0.25(OH)2 precursor, 4780 parts by weight of lithium hydroxide, 36 parts by weight of ZrO2, 19 parts by weight of Al2O3, and 10 parts by weight of B2O3 were well mixed and put into a saggar and sintered at a high temperature in a roller kiln under an oxygen-containing atmosphere. During the sintering, the temperature of the upper layer of the heat preservation zone of the roller kiln was set to 923° C., and the temperature of the lower layer was set to 930° C. (considering the gap and heat conduction between the temperature-measuring block and the inner walls of the temperature-measuring box, the temperature difference between the upper layer and the lower layer of the roller kiln was set to Δt+2° C.). The holding time of the high-temperature section was 10.5 h, and the total sintering period was 26 h.
The pieces of material of the surface layer and the bottom layer inside the saggar after second sintering were taken for analysis of microstructure, and respectively prepared into finished products for half-cell test. The test method was to charge cells to 4.35 V first, and then discharge at a rate of 0.1 C with a cut-off voltage of 2.8 V.
Test results: SEM results of the pieces of material of the surface layer and the bottom layer show that the produced primary particles of materials at the surface layer and the bottom layer are equivalent and show no significant difference. Simultaneously, the half-cell prepared from the material at the upper layer had a capacity per gram of 193 mAh, and the one prepared from the material at the lower layer had a capacity per gram of 192 mAh, which were almost at the same level, indicating high consistency of the products.
A process for producing a cathode material of LiCo0.9859Al0.0093Mg0.0047O2 comprised the following steps.
(1) Measurement of temperature difference: 10000 parts by weight of Co3O4 precursor, 4800 parts by weight of lithium carbonate, 60 parts by weight of Al2O3, and 24 parts by weight of MgO were well mixed and put into a saggar. During saggar-loading, two temperature-measuring boxes containing a temperature-measuring block were separately embedded in a bottom layer and a surface layer of a material. After the temperature-measuring block was placed into the temperature-measuring box, the box was covered with a cover of the temperature-measuring box. 1 row of saggar was fed, and 8 rows of empty saggars were respectively arranged before and after the feeding saggar to keep the temperature even, so as to ensure a temperature of the material to be substantially the same as the temperature of the material while continuously feeding raw materials into the kiln. Then, high-temperature sintering was carried out in an oxygen-containing atmosphere. The temperature-measuring box was made by cutting pieces of sintered LiCo0.9859Al0.0093 Mg0.0047O2 cathode material. The temperature-measuring block was placed into a temperature-measuring box, leaving gaps from inner walls of the box. The width of the gaps was 10% of the respective lengths of two mutually perpendicular straight lines passing through the center of the temperature-measuring block. During the sintering, the temperature of an upper layer and a lower layer of the heat preservation zone of the roller kiln was both set to 1020° C. The holding time of the high-temperature section was 14 h, and the total sintering period was 32 h. After discharging, the pieces of material were broken apart, to take out the temperature-measuring box, and then temperature-measuring block. According to the shrinkage of the temperature-measuring block, the temperature difference between the surface layer and the bottom layer of the material was quantitatively determined as Δt=7° C.;
(2) Second sintering: 10000 parts by weight of Co3O4 precursor, 4800 parts by weight of lithium carbonate, 60 parts by weight of Al2O3, and 24 parts by weight of MgO were well mixed and put into a saggar and sintered at a high temperature in a roller kiln under an oxygen-containing atmosphere. During the sintering, the temperature of the upper layer of the heat preservation zone of the roller kiln was set to 1020° C., and the temperature of the lower layer was set to 1029° C. (considering the gap and heat conduction between the temperature-measuring block and the inner walls of the temperature-measuring box, the temperature difference between the upper layer and the lower layer of the roller kiln was set to Δt+2° C.). The holding time of the high-temperature section was 14 h, and the total sintering period was 32 h.
The pieces of material of the surface layer and the bottom layer inside the saggar after second sintering were taken for analysis of microstructure, and respectively prepared into finished products for half-cell test. The test method was to charge cells to 4.35 V first, and then discharge at a rate of 0.1 C with a cut-off voltage of 2.8 V.
Test results: SEM results of the pieces of material of the surface layer and the bottom layer show that the produced primary particles of materials at the surface layer and the bottom layer are equivalent and show no significant difference. Simultaneously, the half-cell prepared from the material at the upper layer had a capacity per gram of 191 mAh, and the one prepared from the material at the lower layer had a capacity per gram of 192 mAh, which was almost at the same level, indicating high consistency of the products.
A process for producing LiNi0.5476Co0.1195Mn0.3286Zr0.0043O2 cathode material comprised the following steps:
10000 parts by weight of Ni0.55Co0.12Mn0.33(OH)2 precursor, 4250 parts by weight of lithium carbonate and 36 parts by weight of ZrO2 were well mixed and put into a saggar and sintered at a high temperature in a roller kiln under an oxygen-containing atmosphere. During the sintering, the temperature of an upper layer and a lower layer of the heat preservation zone of the roller kiln was both set to 935° C.
The pieces of material of the surface layer and the bottom layer inside the saggar after sintering were taken for analysis of microstructure, and respectively prepared into finished products for half-cell test. The test method was to charge cells to 4.35 V first, and then discharge at a rate of 0.1 C with a cut-off voltage of 2.8 V.
Test results: SEM results of the pieces of material of the surface layer and the bottom layer are shown in
The above-mentioned examples are the preferred embodiments of the present disclosure, but they do not limit the embodiments of the present invention, and any other changes, modifications, substitutions, combinations and simplification made without departing from the spirit or principle of the present invention should be deemed as equivalent substitutions, and included in the protection scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202111439757.7 | Nov 2021 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2022/114288 | 8/23/2022 | WO |
