Studies on Structures and Anode Behaviors of Lithium Storage Intermetallic Compounds

1.采用X射线衍射和中子衍射相结合的方法研究了锂二次电池负极材料Li_xMg_2Ge的局域结构。研究发现，电化学锂化Mg_2Ge晶格后，Ge-Mg原子间最近距离略有增加，形成固溶体.为了获得新型锂电池负极材料，研究了机械合金化法合成Mg_2Sn的电化学性能。结果表明，在Mg_2Sn中可以发生大量锂的可逆嵌脱。随着MA时间的延长，Mg_2Sn的晶体结构由立方相转变为正交相。该化合物具有正交晶相，具有良好的阳极性能。Mg_2Sn电极经过20次充放电循环后，放电容量仍保持在250-300 mA·h·g ~<-1>（-1）.使用MA合成A1 Sb。电化学性能 ...更多信息 研究了不同MA时间合成的A1 Sb电极的电化学行为。首次充电（锂插入）的A1 Sb电极的容量随着MA时间的增加而下降。然而，重复充放电循环的放电容量没有表现出相同的依赖性。由20 h MA样品组成的电极表现出最长的充电-放电循环寿命，这表明存在最佳程度的内能，来自于由于MA的应变和/或非晶化。用X射线衍射和差示扫描量热法对这些结果进行了评价.电化学测试表明，Mg_2Sb_2电极的首次充放电容量约为1000 mAh/g。850和600 mA h g^<-1>，上级常规石墨电极。Mg_2Sb_2电极的XRD分析表明，在锂嵌入Mg_3Sb_2的过程中，相继生成了LiMgSb和Li_3Sb等含锂化合物。与Mg_3Sb_2电极相比，机械锂化（LiMgSb）电极的循环寿命显著提高。少

1. The local structure of Li_xMg_2Ge, which is a candidate for anode materials of lithium secondary batteries, was investigated using both X-ray diffraction and neutron diffraction. It was found that the nearest interatomic distance of the Ge-Mg increases slightly in electrochemically lithiated Mg_2Ge lattice to form a solid solution.2. To obtain a new anode material of lithium battery, electrochemical properties were investigated on Mg_2Sn synthesized by mechanical alloying (MA) method. As a result, we found that the reversible insertion-extraction of a large amount of lithium can electrochemically occur in the Mg_2Sn. The Mg_2Sn changed its crystal structure from cubic to orthorhombic with increasing MA time. The compound exhibiting good performances as an anode had an orthorhombic phase. The discharge capacity of the Mg_2Sn electrode was still maintained at 250-300 mA h g^<-1> ever after the 20 times charge-discharge cycling.3. A1Sb was synthesized using MA. Electrochemical performa … More nce was examined on the electrodes of A1Sb synthesized with different MA time. The first charge (lithium-insertion) capacity of the A1Sb electrodes decreased with increasing MA time. The discharge capacity on repeating charge-discharge cycle, however, did not show the same dependence. The electrode consisting of the 20 h MA sample exhibited the longest charge-discharge cycle life, suggesting that there is the optimum degree of internal energy, derived from the strain and/or the amorphization due to MA. These results were evaluated using X-ray diffraction and differential scanning calorimetry.4. Electrochemical tests demonstrated that the initial charge and discharge capacities of the Mg_2Sb_2 electrode were ca. 850 and 600 mA h g^<-1> which were superior to those of the conventional graphite electrode. XRD of the Mg_2Sb_2 electrodes showed that several lithium-containing compounds such as LiMgSb and Li_3Sb were successively formed during the insertion of lithium into Mg_3Sb_2. The cycle life performance of mechanically lithiated (LiMgSb) electrode was significantly enhanced in comparison with that of the Mg_3Sb_2 electrode. Less