新型锂离子材料锂锰钴镍氧的制备技术研究

采用解胶法制备成前驱体,经温度梯度煅烧加工后制成成品LiMn1,2Co1／4Ni1／4O2。运用SEM和XRD分析技术研究了成品形貌与结构。将成品制成工作电极,组装了试验电池进行充放电循环测试。结果表明,该技术可以制备球形、电化学性能优良的LiMn1／2Co1／4Ni1／4O2材料,首次放电容量在160mAh／g以上（3．0～4．8V）,300次循环后衰减在6％左右。与传统工业相比,该技术具有成本低、能耗低、环保等特点。     

Lattice correspondence and fivefold twins of the orthorhombic (2/1, 1/1) and (1/0, 2/1) approximants in a Ga-Fe-Cu-Si alloy

In the rapidly solidified and annealed Ga₄₆Fe₂₃Cu₂₃Si₈ alloy, the base-centered orthorhombic (2/1, 1/1) and (1/0, 2/1) approximants of the decagonal quasicrystal, with lattice parameters of a=2.00 nm, b=1.25 nm, and c=1.40 nm and a=0.76 nm, b=1.25 nm, and c=2.40 nm, respectively, were found to coexist with a definite lattice correspondence relationship. At the interphase boundary, their {101} planes and the 〈101〉 directions in these planes coincide. There are four possible types of lattice correspondences which have been confirmed by electron diffraction patterns as well as by high-resolution electron microscopy (HREM) images. Moreover, such lattice correspondence relationships can be accounted for by the structural subunits with angles of n × 72 deg in these two orthorhombic approximants: flattened hexagons in the (1/0, 2/1) approximant, and octagons called “crown” subunits in the (2/1, 1/1) approximant. Various tilings of the crown subunits are discussed. In addition, fivefold rotational twins occur abundantly in both of these approximants and intergrowth between them is common. This can also be explained by their respective characteristic structural subunits.