Improvement of elevated-temperature performance of Li1.02Cr0.1Mn1.9O4 cathode material by silicious surface modification was studied. The Li1.02Cr0.1Mn1.9O4 cathode material was treated by silanes coupling agent and t...Improvement of elevated-temperature performance of Li1.02Cr0.1Mn1.9O4 cathode material by silicious surface modification was studied. The Li1.02Cr0.1Mn1.9O4 cathode material was treated by silanes coupling agent and then heated at 580 ℃ to remove organic material. The structures of the modified and unmodified Li1.02Cr0.1Mn1.9O4 were characterized by SpectraPlus, SEM and XRD. The results show that the surface layer of Li1.02Cr0.1Mn1.9O4 material is found to be rich in silicious compound. X-ray diffraction show that all the samples have perfect spinel structure. The electrochemical characterization of modified Li1.02Cr0.1Mn1.9O4 cathode material was tested. The cycle stability of charge/discharge at 55℃ is improved. The results of the charge/discharge curves show that the modified Li1.02Cr0.1Mn1.9O4 has better performance than those unmodified according to the inhibition of decline of reversible capacity of spinel Li1.02Cr0.1Mn1.9O4. Therefore, cycle performance is improved so obviously that 86.03% of the initial capacity is preserved after 100 cycles.展开更多
Li1.02YxMn2-xO4（x = 0, 0. 005, 0.01, 0.02, 0.04, 0. 1） were prepared by solid state reaction method with raw materials Li2CO3, electrolytic MnO2 and Y2O3. Li1.02YxMn2-x O4 with different Y^3＋ contents have good cry...Li1.02YxMn2-xO4（x = 0, 0. 005, 0.01, 0.02, 0.04, 0. 1） were prepared by solid state reaction method with raw materials Li2CO3, electrolytic MnO2 and Y2O3. Li1.02YxMn2-x O4 with different Y^3＋ contents have good crystal structure, Y^3＋ doping makes the lattice parameter and crystal volume small. Cyclic vohammogram testing result shows that a small quantity of Y^3＋ doping has no influence on the Li^＋ deinsertion-insertion process, but Y^3＋ doping decreases the interacting force among Li^＋ , and then availably avoids the energy level splitting. The electrochemical property testing indicates that the initial discharge ca- pacity at x =0.02 is 117.2 mAh·g^-1 and remains 96.9% with 113.6 mAhg^-1 after 20 cycles, which explains that Y^3＋ doping effectively restricts Jahn-Teller effect and stabilizes the crystal structure. AC analysis shows that conductivity of the samples is clearly improved due to Y^3＋ doping.展开更多
文摘Improvement of elevated-temperature performance of Li1.02Cr0.1Mn1.9O4 cathode material by silicious surface modification was studied. The Li1.02Cr0.1Mn1.9O4 cathode material was treated by silanes coupling agent and then heated at 580 ℃ to remove organic material. The structures of the modified and unmodified Li1.02Cr0.1Mn1.9O4 were characterized by SpectraPlus, SEM and XRD. The results show that the surface layer of Li1.02Cr0.1Mn1.9O4 material is found to be rich in silicious compound. X-ray diffraction show that all the samples have perfect spinel structure. The electrochemical characterization of modified Li1.02Cr0.1Mn1.9O4 cathode material was tested. The cycle stability of charge/discharge at 55℃ is improved. The results of the charge/discharge curves show that the modified Li1.02Cr0.1Mn1.9O4 has better performance than those unmodified according to the inhibition of decline of reversible capacity of spinel Li1.02Cr0.1Mn1.9O4. Therefore, cycle performance is improved so obviously that 86.03% of the initial capacity is preserved after 100 cycles.
文摘Li1.02YxMn2-xO4（x = 0, 0. 005, 0.01, 0.02, 0.04, 0. 1） were prepared by solid state reaction method with raw materials Li2CO3, electrolytic MnO2 and Y2O3. Li1.02YxMn2-x O4 with different Y^3＋ contents have good crystal structure, Y^3＋ doping makes the lattice parameter and crystal volume small. Cyclic vohammogram testing result shows that a small quantity of Y^3＋ doping has no influence on the Li^＋ deinsertion-insertion process, but Y^3＋ doping decreases the interacting force among Li^＋ , and then availably avoids the energy level splitting. The electrochemical property testing indicates that the initial discharge ca- pacity at x =0.02 is 117.2 mAh·g^-1 and remains 96.9% with 113.6 mAhg^-1 after 20 cycles, which explains that Y^3＋ doping effectively restricts Jahn-Teller effect and stabilizes the crystal structure. AC analysis shows that conductivity of the samples is clearly improved due to Y^3＋ doping.
