Preparation Calcination Temperature Research Articles

Optimization of Calcination Temperature in Preparation of a High Capacity Li-Rich Solid-Solution Li[Li0.2Ni0.18Co0.03Mn0.58]O2 Material and Its Cathode Performance in Lithium Ion Battery

In recent years, Li-rich solid-solution layered oxide materials (LLOs) comprising layered LiMO2 (M: transition metals) and Li2MnO3 have attracted much interest as a cathode material for lithium ion battery (LIB) because some materials exhibit capacities as high as 250 mAh g-1 in the voltage range of 2.0 and 4.8 V. Because the Li2MnO3 structure can be reformulated with Li[Li1/3Mn2/3]O2, both of Li2MnO3 and LiMO2 can be considered to be of layered α-NaFeO2-type rock salt structure. The structural compatibility between Li2MnO3, which is electrochemically inactive and has a large theoretical capacity, and LiMO2, which is electrochemically active but offers lower capacity, allows for the structural integration of these components at an atomic level. As a result, the electrochemically inactive Li2MnO3 can participate in the charge/discharge process after activation with oxygen release from the lattice during the charging process and the capacity of LiMO2 can be improved because the Li2MnO3 component acts to stabilize the layered structure of LiMO2 when more than 50% of the Li+ ions are deintercalated. These materials are charged to above 4.5 V (vs. Li/Li+) to fully activate the Li2MnO3 component, and after activation, the cathodes are charged to 4.5 V to reach discharge capacities over 250 mAh g-1. In our previous paper, in order to find the optimal composition of the LLOs exhibiting higher cathode performance, which are composed of Li2MnO3, LiCo1/3Ni1/3Mn1/3O2 and LiNi0.5Mn0.5O2, the selected 75 samples having different composition were synthesized under identical preparation conditions except for the composition and the dependence of the performance of the cathode material on the percentages of Li2MnO3, LiCo1/3Ni1/3Mn1/3O2 and LiNi0.5Mn0.5O2 in the LLO samples was examined in the viewpoint of discharge capacity, retention of discharge capacity, average discharge voltage, energy density and rate capability. In each viewpoint, using ternary phase diagrams of the percentages of Li2MnO3, LiCo1/3Ni1/3Mn1/3O2 and LiNi0.5Mn0.5O2 in the LLO samples, the dependence of each performance on the percentages of Li2MnO3, LiCo1/3Ni1/3Mn1/3O2 and LiNi0.5Mn0.5O2 in the LLO samples was evaluated. The results concluded that among the LLOs examined Li[Ni0.208Li0.183Co0.033Mn0.575]O2 (Li2MnO3 (55%) - LiNi1/2Mn1/2O2 (35%) - LiNi1/3Co1/3Mn1/3O2 (10%)) possesses the best composition as cathode material for LIBs. In this case, Li[Ni0.208Li0.183Co0.033Mn0.575]O2 was synthesized only under the calcination condition of 900 ℃ for 12 h in air. Changing the calcination temperature can be expected to lead to a structural change and consequently a change in cathode performance. Therefore, in order to clarify the relationship between calcination temperature and cathode performance, in other words, between the degree of crystallinity of LLOs and cathode performance, the LLO samples were synthesized at different calcination temperatures in the rage of 800-1100℃ and their structural and cathode performance analyses were carried out in detail in this study.

Optimization of Calcination Temperature in Preparation of a High Capacity Li-Rich Solid-Solution Li[Li0.2Ni0.18Co0.03Mn0.58]O2 Material and Its Cathode Performance in Lithium Ion Battery

In recent years, Li-rich solid-solution layered oxide materials (LLOs) comprising layered LiMO2 (M: transition metals) and Li2MnO3 have attracted much interest as a cathode material for lithium ion battery (LIB) because some materials exhibit capacities as high as 250 mAh g-1 in the voltage range of 2.0 and 4.8 V. Because the Li2MnO3 structure can be reformulated with Li[Li1/3Mn2/3]O2, both of Li2MnO3 and LiMO2 can be considered to be of layered α-NaFeO2-type rock salt structure. The structural compatibility between Li2MnO3, which is electrochemically inactive and has a large theoretical capacity, and LiMO2, which is electrochemically active but offers lower capacity, allows for the structural integration of these components at an atomic level. As a result, the electrochemically inactive Li2MnO3 can participate in the charge/discharge process after activation with oxygen release from the lattice during the charging process and the capacity of LiMO2 can be improved because the Li2MnO3 component acts to stabilize the layered structure of LiMO2 when more than 50% of the Li+ ions are deintercalated. These materials are charged to above 4.5 V (vs. Li/Li+) to fully activate the Li2MnO3 component, and after activation, the cathodes are charged to 4.5 V to reach discharge capacities over 250 mAh g-1. In our previous paper[1], in order to find the optimal composition of the LLOs exhibiting higher cathode performance, which are composed of Li2MnO3, LiCo1/3Ni1/3Mn1/3O2 and LiNi0.5Mn0.5O2, the selected 75 samples having different composition were synthesized under identical preparation conditions except for the composition and the dependence of the performance of the cathode material on the percentages of Li2MnO3, LiCo1/3Ni1/3Mn1/3O2 and LiNi0.5Mn0.5O2 in the LLO samples was examined in the viewpoint of discharge capacity, retention of discharge capacity, average discharge voltage, energy density and rate capability. In each viewpoint, using ternary phase diagrams of the percentages of Li2MnO3, LiCo1/3Ni1/3Mn1/3O2 and LiNi0.5Mn0.5O2 in the LLO samples, the dependence of each performance on the percentages of Li2MnO3, LiCo1/3Ni1/3Mn1/3O2 and LiNi0.5Mn0.5O2 in the LLO samples was evaluated. The results concluded that among the LLOs examined Li[Ni0.208Li0.183Co0.033Mn0.575]O2 (Li2MnO3 (55%) - LiNi1/2Mn1/2O2 (35%) - LiNi1/3Co1/3Mn1/3O2 (10%)) possesses the best composition as cathode material for LIBs. In this case, Li[Ni0.208Li0.183Co0.033Mn0.575]O2 was synthesized only under the calcination condition of 900 ℃ for 12 h in air. Changing the calcination temperature can be expected to lead to a structural change and consequently a change in cathode performance. Therefore, in order to clarify the relationship between calcination temperature and cathode performance, in other words, between the degree of crystallinity of LLOs and cathode performance, the LLO samples were synthesized at different calcination temperatures in the rage of 800-1100℃ and their structural and cathode performance analyses were carried out in detail in this study. [1] T. Tsuda, H. Kokubun, Y. Asaoka, K. Miyamoto, Y. Mochizuki, T. Gunji, T. Tanabe, S. Kaneko,T. Ohsaka, F. Matsumoto, Dependences of Discharge Capacity, Retention of Discharge Capacity, Average Discharge Voltage and Energy Density, and Rate Capability on the Composition of xLi2MnO3-yLiNi1/2Mn1/2O2-(1-x-y)LiNi1/3Co1/3Mn1/3O2 Li-rich Solid-Solution Cathode Materials for Li-Ion Battery, ECS Transactions, 75(20) (2017) 173–187.

Optimization of calcination temperature in preparation of a high capacity Li-rich solid-solution Li[Li0.2Ni0.18Co0.03Mn0.58]O2 material and its cathode performance in lithium ion battery

In our previous paper [12], it has been reported that Li[Ni0.208Li0.183Co0.033Mn0.575]O2 Li-rich solid-solution layered oxide (LLO) cathode (Li2MnO3 (55%) - LiNi0.5Mn0.5O2 (35%) - LiNi1/3Co1/3Mn1/3O2 (10%)) possesses the best performance as cathode material among the examined LLO cathode materials of Li2MnO3-LiCo1/3Ni1/3Mn1/3O2-LiNi0.5Mn0.5O2 for lithium ion battery. In order to further improve its cathode performance, the calcination temperature was optimized in the range of 800–1100 °C. The cathode performance such as discharge capacity, discharge capacity retention and rate capability was improved with increasing the calcination temperature from 800 to 1000 °C, the best performance was obtained at 1000 °C and at more than 1000 °C, the cathode performance was degraded. The structural analysis with transmission electron microscope (TEM) and Rietveld analysis of XRD patterns indicated that the cation mixing between Li+ ions on the 3a site and Ni2+ ions on the 3b site of the layered oxide structure (R-3m) is reduced significantly in the case of the LLO calcinated at 1000 °C, resulting in the improvement of cathode performance. In addition, the other LLOs having different compositions were also prepared at different calcination temperatures and their cathode performance was tested. The discharge capacity of Li[Ni0.208Li0.183Co0.033Mn0.575]O2 was found to be the highest among all the LLOs examined in this study.

Effect of Calcination Temperature in Preparation of ZnO-SiO2/Laponite and its Physical Character and Photocatalytic Activity

Effect of Calcination Temperature in Preparation of ZnO-SiO2/Laponite and its Physical Character and Photocatalytic Activity

Effect of Preparation Temperature on Cyclic CO2 Capture and Multiple Carbonation−Calcination Cycles for a New Ca-Based CO2 Sorbent

The cyclic CO2 capture, transient phases change, and microstructure appearance of a new kind of Ca-based regenerable CO2 sorbent, CaO/Ca12Al14O33, obtained by the integration of CaO as solid reactant with a composite metal oxide of Ca12Al14O33 as a binder, were investigated by thermogravimetric analysis, XRD, and SEM at different preparation calcination temperatures. When the calcination temperature in the preparation stage is higher than 1000 °C, the cyclic CO2 capture of this new sorbent declines. The lowered CO2 capture may mainly be attributed to the formation of Ca3Al2O6, which decreases the ratio of CaO to binder in sorbent, and the severe sintering of sorbent occurs when calcined at such high temperatures in the preparation processes. These results suggest that the calcination temperature for this new sorbent should not be higher than 1000 °C in order to obtain its high reactivity. The performance of the new sorbent over 50 cycles was evaluated under mild and severe regeneration conditions, respectively. CaO/Ca12Al14O33 attained 41 wt % CO2 capture after 50 carbonation−calcination cycles under mild calcination conditions (850 °C, 100% N2), and the results obtained here indicate that the new sorbent, CaO/Ca12Al14O33, has significantly improved CO2 capture and cyclic reaction stability over multiple carbonation−calcination cycles compared with limestone and dolomite under mild calcination conditions. When more severe calcination conditions (980 °C, 100% CO2) were used, the capture of CaO/Ca12Al14O33 decreased from 52 wt % in the first cycle to about 22 wt % in the 56th cycle; however, the capture of CaO/Ca12Al14O33 sorbent over 56 cycles is still higher than that of dolomite and limestone under the same severe calcination conditions.