| Enhancing the Li/Na-Ion Battery Performances by Disorder/Order Engineering Yuanzheng Yue1; 1AALBORG UNIVERSITY, Aalborg, Denmark; PAPER: 120/Molten/Keynote (Oral) SCHEDULED: 12:10/Fri. 25 Oct. 2019/Ambrosia A (77/RF) ABSTRACT: We are facing big challenges in developing full-solid Li/Na ion batteries concerning the limited performances and problems of electrodes and solid electrolytes. There are, however, potential possibilities to overcome these challenges. In this presentation, we demonstrate a different route, that is, our disorder/ordering engineering concept [1] to develop high performance cathode/anode/electrolyte materials. The disorder/order engineering refers to two aspects. First, part of the disordered or glass structure in cathode/anode materials is transformed into the ordered domains. Second, the long-range ordered solids are transformed into disordered or amorphous ones. In this talk, we present three case studies concerning the effect of the disorder/order engineering on the electrochemical performances of cathodes, anodes, and solid electrolytes, respectively, for Li/Na-ion batteries. <br />Case 1: A series of vanadium-tellurite glasses with various V/Te ratios were synthesized via melt-quenching [1,2]. Then, the glass was pulverized and mixed with carbon to make Li-ion battery anodes. The anodes underwent discharging/charging cycles. During cycling, a fascinating phenomenon was observed, i.e., nanocrystals formed in glass matrix. As a consequence, the cycling stability and electronic/ionic conductivity of the anodes were enhanced. This kind of nanocrystal formation has a fundamentally different origin compared to the thermally induced crystallization [1,3].<br />Case 2: NaFePO<sub>4</sub> with maricite structure, which is a thermodynamically stable phase, was considered to be electrochemically inactive for sodium-ion storage. Recently, we succeeded in creating disorder in the NaFePO4 cathode by a mechanochemical route to enhance electrochemical performances of Na-ion batteries [4]. The derived NaFePO<sub>4</sub> cathodes containing both amorphous and maricite phases exhibit much improved sodium storage performance with an initial capacity of 115 mA h g<sup>-1</sup> at 1 C and an excellent cycling stability of capacity retention of 91.3% after 800 cycles.<br />Case 3: The crystalline Ag<sub>3</sub>PS<sub>4</sub> was transformed into amorphous state via a chemo-mechanical milling process. The Ag<sup>+</sup> conductivity of the amorphous sample was found to be about three orders of magnitude higher than that of the crystalline counterpart. The amorphous sample exhibits lower activation energy (<i>E</i><sub>a</sub>) for the Ag<sup>+</sup> migration, and hence, lower Ag+ conductivity compared to the crystalline one. By performing structural characterizations, we explored the origin of the enhanced Ag<sup>+</sup> conductivity of the amorphous sample. The present study provides valuable information for developing solid electrolytes. References: 1. Y.F. Zhang, P.X. Wang, T. Zheng, D.M. Li, G.D. Li, Y.Z. Yue. Enhancing Li-ion battery anode performances via disorder/order engineering. Nano Energy 49 (2018) 596-602.<br />2. J. Kjeldsen, Y.Z. Yue, C.B. Bragatto, A.C.M. Rodrigues. Electronic Conductivity of Vanadium-Tellurite Glass-Ceramics. J. Non-Cryst. Solids 378 (2013) 196-200.<br />3. Y.F. Zhang, P.X. Wang, G.D. Li, J.H. Fan, C.W. Gao, Z.Y. Wang, Y.Z. Yue, Clarifying the charging induced nucleation in glass anode of Li-ion batteries and its enhanced performances, Nano Energy 57 (2019) 592-599.<br />4. F.Y. Xiong, Q.Y. An, L.X. Xia, Y.Zhao, L.Q. Mai, H.Z. Tao, Y.Z. Yue, Revealing the atomistic origin of the disorder-enhanced Na-storage performance in NaFePO<sub>4</sub> battery cathode, Nano Energy 57 (2019) 608-615. |
