Li Yunjiao

Co掺杂改性尖晶石型Li 1.035 Mn 1.965 O 4 的合成及其电化学性能

Spinel powders of Li1.035CoxMn1.965-xO4 (x=0-0.100) systems were synthesized by a simple wet chemical process with post heat-treatment. X-ray diffraction patterns (XRD) reveal that the Co doping does not affect the Fd3m space group of the cathode materials. Scanning electron microscope (SEM) images show that the Li1.035CoxMn1.965-xO4 cathode materials have a uniform and nearly cubic morphology with a narrow size distribution. Transmission electron microscope (TEM) results demonstrate that the Li1.035Co0.035Mn1.930O4 powder has a good crystalline state. The electrochemical testing results indicate that the prepared Co-doped Li1.035CoxMn1.965-xO4 samples show a better cycling ability and rate capability at room temperature than that of Co-free Li1.035Mn1.965O4. In particular, the Li1.035 Co0.035Mn1.930O4 sample delivers a reversible specific capacity of 113 mAh/g in 1 st cycle and retains 93.8% of its initial capacity after 100 cycles at 0.5C rate. When discharging at 4C rate, the Li1.035Co0.035Mn1.930O4 powder maintains 86 mAh/g, which is 76.1% of the reversible capacity at 0.5C. Comparatively, the Li1.035Mn1.965O4 powder maintains only 64.8% of its reversible capacity at 0.5C discharge rate. The electrochemical impedance spectroscopy results show that Co ion doping can enhance the electrical conductivity and the Li-ion diffusion coefficient. These results indicate a superior cycling and rate performance compared with the pristine one.采用湿化学–后续热处理技术, 合成了掺钴尖晶石锰酸锂材料。X射线衍射(XRD)分析结果表明, 钴的掺入没有改变材料的Fd3m结构。扫描电子显微镜(SEM)分析表明, 所合成的材料颗粒均匀, 形貌规整, 粒径分布较窄。透射电子显微镜(TEM)结果表明, Li 1.035 Co 0.035 Mn 1.930 O 4 具有完好的结晶态。充放电测试结果表明, 在室温下钴掺杂能够提高材料的电性能。当产物为Li 1.035 Co 0.035 Mn 1.930 O 4 时, 其电性能达到最优: 以0.5 C 充放电，首次放电容量为113 mAh/g, 经过100次循环后容量保持率为93.8%, 经过4 C 放电后仍然能够保持0.5 C 放电容量的76.1%; 而未掺钴的Li 1.035 Mn 1.965 O 4 经过4C放电容量仅保持0.5 C 放电容量的64.8%。电化学阻抗测试结果表明, 钴离子的掺杂能够提高锰酸锂材料的锂离子扩散速率。采用湿化学–后续热处理技术, 合成了掺钴尖晶石锰酸锂材料。X射线衍射(XRD)分析结果表明, 钴的掺入没有改变材料的Fd3m结构。扫描电子显微镜(SEM)分析表明, 所合成的材料颗粒均匀, 形貌规整, 粒径分布较窄。透射电子显微镜(TEM)结果表明, Li 1.035 Co 0.035 Mn 1.930 O 4 具有完好的结晶态。充放电测试结果表明, 在室温下钴掺杂能够提高材料的电性能。当产物为Li 1.035 Co 0.035 Mn 1.930 O 4 时, 其电性能达到最优: 以0.5 C 充放电，首次放电容量为113 mAh/g, 经过100次循环后容量保持率为93.8%, 经过4 C 放电后仍然能够保持0.5 C 放电容量的76.1%; 而未掺钴的Li 1.035 Mn 1.965 O 4 经过4 C 放电容量仅保持0.5 C 放电容量的64.8%。电化学阻抗测试结果表明, 钴离子的掺杂能够提高锰酸锂材料的锂离子扩散速率。