Department of Energy Engineering, Hanyang University , Seoul 133-791, South Korea.
Nano Lett. 2014 Aug 13;14(8):4873-80. doi: 10.1021/nl5022859. Epub 2014 Jun 30.
Cathode materials with high energy density for lithium-ion batteries are highly desired in emerging applications in automobiles and stationary energy storage for the grid. Lithium transition metal oxide with concentration gradient of metal elements inside single particles was investigated as a promising high-energy-density cathode material. Electrochemical characterization demonstrated that a full cell with this cathode can be continuously operated for 2500 cycles with a capacity retention of 83.3%. Electron microscopy and high-resolution X-ray diffraction were employed to investigate the structural change of the cathode material after this extensive electrochemical testing. It was found that microstrain developed during the continuous charge/discharge cycling, resulting in cracking of nanoplates. This finding suggests that the performance of the cathode material can be further improved by optimizing the concentration gradient to minimize the microstrain and to reduce the lattice mismatch during cycling.
锂离子电池用高能量密度阴极材料在汽车和电网固定储能等新兴应用领域受到高度关注。本研究旨在探索具有金属元素浓度梯度的单颗粒锂过渡金属氧化物作为一种有前途的高能量密度阴极材料。电化学测试表明，采用该阴极的全电池可在 2500 次循环中持续运行，容量保持率为 83.3%。电子显微镜和高分辨率 X 射线衍射用于研究在这种广泛的电化学测试后阴极材料的结构变化。结果发现，在连续的充放电循环过程中产生了微应变，导致纳米板出现裂纹。这一发现表明，通过优化浓度梯度来最小化微应变并减少循环过程中的晶格失配，可以进一步提高阴极材料的性能。
