Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Science. 2014 Jan 31;343(6170):519-22. doi: 10.1126/science.1246432. Epub 2014 Jan 9.
Nearly all high-energy density cathodes for rechargeable lithium batteries are well-ordered materials in which lithium and other cations occupy distinct sites. Cation-disordered materials are generally disregarded as cathodes because lithium diffusion tends to be limited by their structures. The performance of Li1.211Mo0.467Cr0.3O2 shows that lithium diffusion can be facile in disordered materials. Using ab initio computations, we demonstrate that this unexpected behavior is due to percolation of a certain type of active diffusion channels in disordered Li-excess materials. A unified understanding of high performance in both layered and Li-excess materials may enable the design of disordered-electrode materials with high capacity and high energy density.
几乎所有用于可充电锂电池的高能量密度阴极都是有序材料，其中锂离子和其他阳离子占据不同的位置。无序材料通常被视为阴极的禁忌，因为锂离子扩散往往受到其结构的限制。Li1.211Mo0.467Cr0.3O2 的性能表明，无序材料中的锂离子扩散可以很容易地进行。通过从头算计算，我们证明这种出乎意料的行为是由于无序富锂材料中某种类型的活性扩散通道的渗透。对层状材料和富锂材料的优异性能的统一理解，可能使具有高容量和高能量密度的无序电极材料的设计成为可能。
