Combinatorial exploration of newly pseudo-quintenary layered-type Li-Ni-Co-Fe-Ti oxides
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Combinatorial exploration of newly pseudo-quintenary layered-type Li-Ni-Co-Fe-Ti oxides Kenjiro Fujimoto1, Tomoyuki Kanno1, Keita Ikezawa1, Yuichiro Imanari2, Maiko Sakai2, Kenji Nakane2 and Shigeru Ito1 1 Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science Yamazaki 2641, Noda, Chiba 278-8510, Japan 2 Tsukuba Materials Development Laboratory, Sumitomo Chemical Co., Ltd. Kitahara 6, Tsukuba, Ibaraki 300-3294, Japan ABSTRACT In order to decrease the use of cobalt element as in LiCoO2,which is mainly used for cathode materials in lithium ion secondary batteries, a newly pseudo-quintenary layered-type Fedoped Li-Ni-Co-Ti oxides library was created using the combinatorial technology "M-ist Combi system" based on the electrostatic spray deposition method. The starting materials used were LiNO3, Ni(NO3)2·6H2O, Co(NO3)2·6H2O, Fe(NO3)3·9H2O and TiO2 nano-slurry. These materials were dissolved or dispersed in a mixture of ethanol and butyl carbitol and mixed in a predefined ratio, respectively. Subsequently, each of the mixtures was sprayed and dried on a grounded reaction plate that was heated to 400˚C. The deposited powder was sintered at 700˚C for 5 hours in air atmosphere. Phase identification of the obtained powder library was evaluated by a combinatorial powder x-ray diffractometer. A reaction phase diagram was established from the structure information and chemical composition by ICP-AES measurement. From all results, single-phase layered-type compounds showed the composition region that included many Co and Ni elements. On the other hand, single phase spinel-type compounds existed in the Ti-rich composition region. INTRODUCTION Layered-type LiCoO2 is a well-known cathode material for lithium ion secondary batteries. The material has important drawbacks, however, as the cobalt element is both toxic and expensive. We have hitherto found the single phase of layered-type Li(Ni,Co,Ti)O2 (Ni≤0.8, Ti≤ 0.2) powder can be obtained at 700˚C by using our combinatorial material exploration system "M-ist Combi" based on the electrostatic spray deposition (ESD) method. And, from chargedischarge properties of the Li(Ni,Co,Ti)O2 powder library in a voltage range from 4.2 V to 2.8 V at 1C, LiNixCo0.9-xTi0.1O2 (0≤x≤0.6) compounds showed a particularly favorable cycle property. [1] Some Li-Fe oxides are also promising cathode materials for lithium ion secondary batteries. LiFeO2 with the α-NaFeO2 structure shows a good cycle performance in the range of 1.5V ~ 3.0V. [2] LiFePO4 with the olivine structure showed good rate capability and excellent stability. [3] In this study, we focused on the exploration of newly Fe-doped layered-type Li-Ni-Co-Ti oxide in order to find electrode materials superior to the layered-type Li(Ni,Co,Ti)O2.
EXPERIMENT A powder library was prepared by “M-ist Combi” a fully automated high-throughput material exploration system developed by our group based on the electrostatic spray deposition (ESD) method [4]. In ESD, a high voltage is applied to a liquid to g
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