Academia.eduAcademia.edu

Figure 3 – uploaded by Eda Yılmaz

See full PDFdownloadDownload figure
Table 3. All ingredients of 6 different compositions of the clear solution used in sample preparation with a constant Li/Ti” molar ratio of 0.8 an varying Li/P123 and Ti‘/P123 molar ratios.

Table 3 All ingredients of 6 different compositions of the clear solution used in sample preparation with a constant Li/Ti” molar ratio of 0.8 an varying Li/P123 and Ti‘/P123 molar ratios.

Related Figures (10)

Figure 1. Small-angle XRD patterns of the fresh samples: a) with increasing CTAB/P123 molar ratio (bottom to top: 4, 5, 6, 7, 8, 10, 11, 12, 13, and 14) at a constant Li'/P123 molar ratio of 28 and Li/Ti’ molar ratio of 0.8, and b) with increasing Li!/P123 molar ratio (bottom to top: 20, 28, 36, 40, 52, 60, and 72) at a constant CTAB/P123 molar ratio of 14 and Li/Ti" of 4/5.
Figure 1. Small-angle XRD patterns of the fresh samples: a) with increasing CTAB/P123 molar ratio (bottom to top: 4, 5, 6, 7, 8, 10, 11, 12, 13, and 14) at a constant Li'/P123 molar ratio of 28 and Li/Ti’ molar ratio of 0.8, and b) with increasing Li!/P123 molar ratio (bottom to top: 20, 28, 36, 40, 52, 60, and 72) at a constant CTAB/P123 molar ratio of 14 and Li/Ti" of 4/5.
Table 1. Liquid nitrogen (77 K) sorption parameters of samples calcinec at 350°C and annealed at 400°C with various Li!/P123 molar ratio (X i: 350-400, SA =surface area, PS=pore size, PV=pore volume).
Table 1. Liquid nitrogen (77 K) sorption parameters of samples calcinec at 350°C and annealed at 400°C with various Li!/P123 molar ratio (X i: 350-400, SA =surface area, PS=pore size, PV=pore volume).
Figure 2. Nitrogen (77 K) sorption isotherms of a) CA28-350-400 with in- creasing CTAB/P123 ratios (bottom to top) of 4, 9, and 14; b) desorption branch pore size distribution plots of the same samples as those shown in a); c) nitrogen (77 K) sorption isotherms of CA20-350-400, CA28-350-400, CA36-350-400, CA40-350-400, CA52-350-400, CA60-350-400, and CA72-350- 400 (bottom to top) with increasing Li!/P123 molar ratio; and d) desorption branch pore size distribution plots of the same samples as those shown in c). The fresh samples were immediately calcined at 350°C and annealed at 400°C for 2 h. Figure 2 displays a set of nitrogen
Figure 2. Nitrogen (77 K) sorption isotherms of a) CA28-350-400 with in- creasing CTAB/P123 ratios (bottom to top) of 4, 9, and 14; b) desorption branch pore size distribution plots of the same samples as those shown in a); c) nitrogen (77 K) sorption isotherms of CA20-350-400, CA28-350-400, CA36-350-400, CA40-350-400, CA52-350-400, CA60-350-400, and CA72-350- 400 (bottom to top) with increasing Li!/P123 molar ratio; and d) desorption branch pore size distribution plots of the same samples as those shown in c). The fresh samples were immediately calcined at 350°C and annealed at 400°C for 2 h. Figure 2 displays a set of nitrogen
Figure 3. a) XRD patterns of samples calcined at 350°C and annealed at 450°C for 2 h for CAxx-350-450 samples (xx values are 20, 36, 40, 52, 60, and 72 from top to bottom). b) XRD patterns of LTO samples of CA60-350-500 (top; calcined for 30 min and annealed for 30 min), CA60-500-500 in 50 min (middle; cal- cined from 150 to 500°C and annealed at 500°C for 30 min), and C60-500 (bottom; directly calcined at 500°C for 30 min). c) Raman spectra of the same sam- ples as those shown in b).
Figure 3. a) XRD patterns of samples calcined at 350°C and annealed at 450°C for 2 h for CAxx-350-450 samples (xx values are 20, 36, 40, 52, 60, and 72 from top to bottom). b) XRD patterns of LTO samples of CA60-350-500 (top; calcined for 30 min and annealed for 30 min), CA60-500-500 in 50 min (middle; cal- cined from 150 to 500°C and annealed at 500°C for 30 min), and C60-500 (bottom; directly calcined at 500°C for 30 min). c) Raman spectra of the same sam- ples as those shown in b).
Figure 4. a) Nitrogen-sorption isotherms and b) pore size distribution plots of the samples: |) CA60-350-500 and II) CA60-150-500. Both XRD and Raman data confirm that nanocrystalline LTO forms upon calcination of the lithium salt-pluronic mesophas- es. However, nitrogen-sorption measurements provide more detailed information regarding the pore systems of two sam- ples: CA60-150-500 and C60-350-500 (Figure 4). Both samples
Figure 4. a) Nitrogen-sorption isotherms and b) pore size distribution plots of the samples: |) CA60-350-500 and II) CA60-150-500. Both XRD and Raman data confirm that nanocrystalline LTO forms upon calcination of the lithium salt-pluronic mesophas- es. However, nitrogen-sorption measurements provide more detailed information regarding the pore systems of two sam- ples: CA60-150-500 and C60-350-500 (Figure 4). Both samples
Table 2. The average discharge capacity values at each step of the elec trochemical measurements for CAxx-X (X is 350-450).
Table 2. The average discharge capacity values at each step of the elec trochemical measurements for CAxx-X (X is 350-450).
Figure 6. a) Cyclic stability at a current rate of 2C for 50 cycles and b) rate capabilities of CA28-350-450, CA40-350-450, CA52-350-450, and CA60-350- 450. Among the materials tested, the CA40-350-450 sample, which was spin coated at a spin rate of 1750 rpm, displayed the best electrochemical performance (Figure 7). The material yielded a high irreversible discharge capacity in the first cycles
Figure 6. a) Cyclic stability at a current rate of 2C for 50 cycles and b) rate capabilities of CA28-350-450, CA40-350-450, CA52-350-450, and CA60-350- 450. Among the materials tested, the CA40-350-450 sample, which was spin coated at a spin rate of 1750 rpm, displayed the best electrochemical performance (Figure 7). The material yielded a high irreversible discharge capacity in the first cycles
Figure 5. TEM images CA40-350-450 thin films at different magnifications.
Figure 5. TEM images CA40-350-450 thin films at different magnifications.
Figure 7. a) First 7 charge—discharge curves of CA40-350-450 at C/2. b) Last 5 charge-discharge curves of CA40-350-450 at C/2. c) Cyclic stability at a cur- rent rate of 2C for 50 cycles. d) Rate capability of CA40-350-450. [a] Values with no standard deviation indicate single measurements.
Figure 7. a) First 7 charge—discharge curves of CA40-350-450 at C/2. b) Last 5 charge-discharge curves of CA40-350-450 at C/2. c) Cyclic stability at a cur- rent rate of 2C for 50 cycles. d) Rate capability of CA40-350-450. [a] Values with no standard deviation indicate single measurements.
Figure 8. a) First 7 charge—discharge curves of CA60-350-450 at C/2. b) First 7 charge-discharge curves of CA60-350-450-C at C/2. c) Cyclic stabilities at a current rate of 2C for 50 cycles. d) Rate capabilities of CA60-350-450 and CA60-350-450-C. Mesoporous LTO materials were also prepared by burning the surfactant under vacuum conditions to generate in situ carbon in the pores. Although LTO is known for its SEl-free sur- face, we observed some irreversible discharge capacity in the materials during the first few cycles. As mentioned earlier, this was likely to be due to thin pore walls and surface peroxides. Although the electronic conductivities of the LTO films are al- ready excellent and there is no need to further boost the con- ductivity, the carbon coating helps to prevent the irreversible discharge capacity, as observed in the initial cycles. Figure 8 shows that there is almost no SEI formation in the first charge- discharge cycles of the CA60-350-450-C film. The open-circuit potential of the CA60-350-450-C film was reduced to about 1.5 V. This was expected because carbon offered a lower po- tential difference against the Li*/Li electrode.” It also provided a lower capacity during cyclic stability and rate capability measurements, which could be explained by the additional in- active weight of carbon present in the structure.
Figure 8. a) First 7 charge—discharge curves of CA60-350-450 at C/2. b) First 7 charge-discharge curves of CA60-350-450-C at C/2. c) Cyclic stabilities at a current rate of 2C for 50 cycles. d) Rate capabilities of CA60-350-450 and CA60-350-450-C. Mesoporous LTO materials were also prepared by burning the surfactant under vacuum conditions to generate in situ carbon in the pores. Although LTO is known for its SEl-free sur- face, we observed some irreversible discharge capacity in the materials during the first few cycles. As mentioned earlier, this was likely to be due to thin pore walls and surface peroxides. Although the electronic conductivities of the LTO films are al- ready excellent and there is no need to further boost the con- ductivity, the carbon coating helps to prevent the irreversible discharge capacity, as observed in the initial cycles. Figure 8 shows that there is almost no SEI formation in the first charge- discharge cycles of the CA60-350-450-C film. The open-circuit potential of the CA60-350-450-C film was reduced to about 1.5 V. This was expected because carbon offered a lower po- tential difference against the Li*/Li electrode.” It also provided a lower capacity during cyclic stability and rate capability measurements, which could be explained by the additional in- active weight of carbon present in the structure.
Related topics:
Chemical EngineeringMaterials ScienceChemistryElectrochemistryMedicineLithium Ion BatteriesAnnealing TemperaturesElectrochemical characterizations
580 California St., Suite 400
San Francisco, CA, 94104
© 2025 Academia. All rights reserved