Development Of Non Aqueous Asymmetric Hybrid Supercapacitors Part Iii

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  • 1. DEVELOPMENT OF NON-AQUEOUS ASYMMETRIC HYBRID SUPERCAPACITORS BASED ON Li-ION INTERCALATED COMPOUNDSGUIDEDr.D.KALPANA, SCIENTIST, BYEEC DIVISION, NAKKIRAN.A,CECRI,KARAIKUDI.
  • 2. An overview of previous presentations Introduction Hybrid supercapacitors Synthesis of LiMn2O4 and the same multidoped with Ni, Co and Cu Physical characterization - XRD, SEM, FTIR Cell Fabrication Electrochemical characterizations Comparison of their performances
  • 3. Study of supercapacitors Having LiCo1-xAlxO2 as cathodes (where x=0,0.2,0.4 and 0.6)
  • 4. Lithium Cobaltate(LiCoO2) Commercially successful The layered structure of LiCoO2 enables easy diffusion of Li-ions in and out of the structure
  • 5. Why Aluminum There has recently been considerable interest in Al- doping of lithium intercalation oxides. Al substitution of the transition-metal cation has been shown theoretically and experimentally to increase the cell voltage. Some other advantages of Al are that it is light, non- toxic, and inexpensive
  • 6. Advantage The similarity of Al and Co ions in these lithium metal oxides makes Al an attractive choice for doping The end members, a-LiAlO2 and LiCoO2, have the same crystal structure, layered a-NaFeO2 and the metal ions are close in size. These similarities remove the complications of phase transitions and lattice strain when varying doping content.
  • 7. Synthesis Of Cathode Material Two cathode materials synthesized are, i) Pure LiCoO2 ii) LiCoO2 doped with Al - LiCo1-xAlxO2 ( x = 0.2, 0.4,0.6 ) The cathode material was synthesized by soft combustion method Compositions were taken on a stoichometric ratio based on following equations, LiNO3 + Co(NO3)2.6H2O LiCoO2 (for pure substance) LiNO3 + (1-x) Co(NO3)2.6H2O + xAl(NO3)2.9H2O LiCo1-xAlxO2 (for doped substance)
  • 8. Composition of precursors required for synthesis Basis : 0.2 moles of product Weight of the material Precursor X=0 X=0.2 X=0.4 X=0.6 LiNO3 13.8g 13.8 g 13.8g 13.8 Al(NO3)2.9H2O - 15 g 30g 45g Co(NO3)2.6H2O 58.2g 46.56 g 34.92g 23.28gGlycine(C2H5NO2) 30g 30 g 30g 30g Distilled Water 100ml 100 ml 100ml 100mlX= Fraction of Aluminium
  • 9. The Soft Combustion Process Weighing of required chemicals Dissolve in 100ml distilled water Stir well at 600C Heat the mixture at 1000C for 8 hours Product is formed following a soft combustion
  • 10. Physical Characterization Thermal Analysis X-Ray Diffraction FTIR
  • 11. Thermal Analysis TGA is used to find the optimum temperature ranges for drying a sample to remove the moisture and impurities from it. In DTA phase transitions or chemical reactions are followed through observation of heat absorbed or liberated.
  • 12. TGA Curves 1.0 0.9Weight fraction 0.8 0.7 0.6 LiCoO2 LiCo0.8Al0.2O2 0.5 LiCo0.6Al0.4O2 LiCo0.4Al0.6O2 0.4 0 200 400 600 800 1000 1200 1400 0 Temperature ( C)
  • 13. DTA Curves 2.0 1.5Temperature difference( C)0 1.0 0.5 0.0 -0.5 LiCoO2 -1.0 LiCo0.8Al0.2O2 LiCo0.6Al0.4O2 -1.5 LiCo0.4Al0.6O2 -2.0 0 200 400 600 800 1000 1200 0 Temperature( C)
  • 14. TGA Curves The initial weight drop from 300C-1500C is due to moisture removal from the sample. the subsequent weight loss from 1500C to 3000Ccorresponds to elimination of organic compounds from samples. Next weight drop in the temperature range of 3000C-5000C is formed as a result of the reaction of unreacted precursors to give the final product. The stabilization temperature for these samples mostly lay after 8000C. So the samples are heated at 8000C for 4 hours.
  • 15. FTIR Curves 100 80 60% Transmittance 40 LiCoO2 LiCo0.8Al0.2O2 LiCo0.6Al0.4O2 20 LiCo0.4Al0.6O2 0 500 1000 1500 2000 2500 3000 3500 -1 Wave numbers(cm )
  • 16.  These are the FTIR spectroscopes of LiCoO2, LiCo0.8Al0.2O2, LiCo0.6Al0.4O2, and LiCo0.4Al0.6O2 respectively For high level of Al substitution, the broadening of the infrared peaks can be interpreted as an increase in CoO6 distortion due to the incorporation of Al3+ in the Co3+ site.
  • 17. XRD Patterns (003) (104) (006) LiCo0.4Al0.6O2 (101) (012) (107) (108) (105) (110) (113) (201) LiCo0.6Al0.4O2 LiCo0.8Al0.2O2 LiCoO210 20 30 40 50 60 70 80 90 100 2 theta
  • 18.  All samples are single phase and have the α-NaFeO2 structure (space group R3m). Miller indices (hkl) are indexed in the hexagonal setting. No impurity phase was detected in the XRD patterns of LiAlyCo1−yO2 On Al doping, the (108) peak shifts towards lower 2θ and the (110) peak shifts towards higher 2θ value
  • 19. XRD Patterns (108) (110) LiCo0.4Al0.6O2 LiCo0.6Al0.4O2 LiCo0.8Al0.2O2 LiCoO2 64 66 68
  • 20. Electrochemical Characterizations Cyclic Voltammetry Electrochemical Impedance Spectroscopy Galvanostatic Charge/Discharge
  • 21. CV of LiCoO2/CNF before cycles 0.0004 0.0002 0.0000Current(A) -0.0002 -0.0004 -0.0006 1mV/s 2mV/s -0.0008 5mV/s 2000 1000 0 -1000 -2000 Voltage(mV)
  • 22. CV of LiCoO2/CNF after 500 cycles 0.0002 0.0000Current(A) -0.0002 1mV/s -0.0004 2mV/s 5mV/s 1500 1000 500 0 -500 -1000 -1500 Voltage(mV)
  • 23. CV of LiCo0.8Al0.2O2/CNF before cycles 0.0004 0.0002Current(A) 0.0000 -0.0002 -0.0004 1mV/s 2mV/s 5mV/s -0.0006 1500 1000 500 0 -500 -1000 -1500 Voltage(mV)
  • 24. CV of LiCo0.8Al0.2O2/CNF after 500 cycles 0.0002 0.0001Current(A) 0.0000 -0.0001 1mV/s 2mV/s 5mV/s -0.0002 1500 1000 500 0 -500 -1000 -1500 Voltage(mV)
  • 25. CV of LiCo0.6Al0.4O2/CNF before cycles 0.00015 0.00010 0.00005Current(A) 0.00000 -0.00005 -0.00010 1mV/s 2mV/s 5mV/s -0.00015 1500 1000 500 0 -500 -1000 -1500 Voltage(mV)
  • 26. CV of LiCo0.6Al0.4O2/CNF after 500 cycles 0.0006 0.0004 0.0002Current(A) 0.0000 -0.0002 1mV/s -0.0004 2mV/s 5mV/s -0.0006 2000 1000 0 -1000 -2000 Voltage(mV)
  • 27. CV of LiCo0.4Al0.6O2/CNF before cycles 0.0004 0.0002Current(A) 0.0000 -0.0002 1mV/s 2mV/s -0.0004 5mV/s 1500 1000 500 0 -500 -1000 -1500 Voltage(mV)
  • 28. CV of LiCo0.4Al0.6O2/CNF after 500 cycles 0.00010 0.00005Current(A) 0.00000 -0.00005 1mV/s 2mV/s -0.00010 1500 1000 500 0 -500 -1000 -1500 Voltage(mV)
  • 29. Specific capacitance (F/g) from CV Scan rate Composition 5mV/s 2mV/s 1mV/s 0 15.93 18.75 20.09 0.2 11.6 15.25 16.3Before cycles 0.4 21.74 26.93 27.61 0.6 6.1 7.63 8.3 0 4.113 5.29 11.95 0.2 8.274 10.33 12.93After cycles 0.4 16.225 19.74 21.51 0.6 - 5.1 6.4
  • 30. Impedance Spectroscopy – Before Cycles -80 LiCoO2 LiCo0.8Al0.2O2 LiCo0.6Al0.4O2 -60 LiCo0.4Al0.6O2ZIm(Ohm) -40 -20 0 0 20 40 60 80 100 ZRe(Ohm)
  • 31. Impedance Spectroscopy – After 500 Cycles -250 LiCoO2 LiCo0.8Al0.2O2 -200 LiCo0.6Al0.4O2 LiCo0.4Al0.6O2 -150ZIm(Ohm) -100 -50 0 0 50 100 150 200 250 ZRe(Ohm)
  • 32. Results of Impedance Spectroscopy Property Rs Cdl x Ohm mF 0 3.747 0.6194 0.2 2.392 0.5518Before cycles 0.4 4.551 0.5491 0.6 5.649 0.6328 0 4.721 0.6567 0.2 6.253 0.5778After cycles 0.4 4.782 0.621 0.6 6.211 0.711
  • 33. Galvanostatic Charge-Discharge behaviour of LiCoO2/CNF 2.1 2.0 1.6 1.4Voltage(V) Voltage(V) 1.2 0.8 0.7 0.4 0.0 0.0 350 400 450 500 550 600 5600 5610 5620 5630 5640 5650 Time(s) Time(s) First cycle 500th cycle
  • 34. Galvanostatic Charge-Discharge behaviour of LiCo0.8Al0.2O2/CNF 2.0 1.6 1.6Voltage(V) Voltage(V) 1.2 0.8 0.8 0.4 0.0 26 28 30 32 34 36 38 40 42 0.0 1337 1338 1339 1340 1341 1342 1343 1344 Time(s) Time(s) First cycle 500th cycle
  • 35. Galvanostatic Charge-Discharge behaviour of LiCo0.6Al0.4O2/CNF 2.0 2.0 1.6 1.6Voltage(V) Voltage(v) 1.2 1.2 0.8 0.8 0.4 0.4 0.0 0.0 600 650 700 750 800 850 900 9120 9140 9160 9180 9200 Time(s) Time(s) First cycle 500th cycle
  • 36. Galvanostatic Charge-Discharge behaviour of LiCo0.4Al0.6O2/CNF 2.0 2.0 1.6 1.6Voltage(V) Voltage(V) 1.2 1.2 0.8 0.8 0.4 0.4 0.0 0.0 105 110 115 120 125 130 135 140 145 11732 11736 11740 11744 11748 11752 Time(s) Time(s) First cycle 500th cycle
  • 37. Results of Galvanostatic Charge-Discharge Analysis Properties Composition Specific Power density Energy density capacitance (kW/kg) (kWh/kg) (F/g) 0 11.17 312.5 12.41 0.2 0.415 303.03 0.44Before cycles 0.4 11.41 333.3 12.68 0.6 1.53 322.58 1.075 0 1.8 312.5 2.01 0.2 0.303 303.03 0.336After cycles 0.4 3.83 333.33 4.25 0.6 0.88 322.58 0.986
  • 38. Conclusion LiCoO2 is a good cathode material for hybrid supercapacitor since it is having specific capacitance of 11 F/g. In the doped cathode materials, LiCo0.6Al0.4O2 is having good capacitance and cycle behaviour.
  • 39. Thank You
  • 40. Queries?