Effects of Phase Change and Cu Doping on the Li Storage Properties of Rutile TiO2 (Supporting Information)

The crystal structure and Li storage properties of Cu-doped rutile TiO2 after a phase change caused by lithiation were investigated for the first time. Structural analysis results confirmed that undoped rutile TiO2 was transformed to a disordered layered rock-salt LixTiO2 structure with a small volume expansion of only 1 % when cycled in a potential range of 1.0–3.0 V vs. Li+/Li. A substitutional solid solution of Cu2+ was formed in layered LixTiO2. The Cu doping increased both the interlayer distance and electronic conductivity of the layered LixTiO2. As an Li-ion battery anode, a Cu-doped TiO2 electrode exhibited a long cycle life, maintaining a reversible capacity of 120 mAh g−1 over 10000 cycles at 5C and an excellent rate capability of 108 mAh g−1 at 50C. Furthermore, this electrode could also be potentially used as a Na storage material. These attractive properties demonstrate high applicability of Cu-doped rutile TiO2 as a novel anode material.

本研究首次对由锂化引起的相变后Cu掺杂锐钛矿TiO2的晶体结构和锂存储特性进行了探究。结构分析结果表明，未掺杂的锐钛矿TiO2在1.0–3.0 V vs. Li+/Li的电位范围内循环时，转变为具有微小体积膨胀（仅1%）的无序层状岩盐结构Li_xTiO_2。在层状Li_xTiO_2中形成了Cu_2+的固溶体。Cu掺杂不仅增加了层状Li_xTiO_2的层间距，还提升了其电子电导率。作为锂离子电池的阳极，Cu掺杂的TiO2电极表现出较长的循环寿命，在5C的条件下，在10000次循环中保持了120 mAh g^-1的可逆容量，并在50C时展现出108 mAh g^-1的优异倍率性能。此外，该电极还可能被用作钠存储材料的潜在候选。这些引人注目的特性展示了Cu掺杂锐钛矿TiO2作为一种新型阳极材料的高应用潜力。