title: Stable alkali metal ion intercalation compounds as optimized metal oxide nanowire cathodes for lithium batteries.
abstract: Intercalation of ions in electrode materials has been explored to improve the rate capability in lithium batteries and supercapacitors, due to the enhanced diffusion of Li(+) or electrolyte cations. Here, we describe a synergistic effect between crystal structure and intercalated ion by experimental characterization and ab initio calculations, based on more than 20 nanomaterials: five typical cathode materials together with their alkali metal ion intercalation compounds A-M-O (A = Li, Na, K, Rb; M = V, Mo, Co, Mn, Fe-P). Our focus on nanowires is motivated by general enhancements afforded by nanoscale structures that better sustain lattice distortions associated with charge/discharge cycles. We show that preintercalation of alkali metal ions in V-O and Mo-O yields substantial improvement in the Li ion charge/discharge cycling and rate, compared to A-Co-O, A-Mn-O, and A-Fe-P-O. Diffraction and modeling studies reveal that preintercalation with K and Rb ions yields a more stable interlayer expansion, which prevents destructive collapse of layers and allow Li ions to diffuse more freely. This study demonstrates that appropriate alkali metal ion intercalation in admissible structure can overcome the limitation of cyclability as well as rate capability of cathode materials, besides, the preintercalation strategy provides an effective method to enlarge diffusion channel at the technical level, and more generally, it suggests that the optimized design of stable intercalation compounds could lead to substantial improvements for applications in energy storage.
authors: State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology , Wuhan 430070, China.
authors: Yunlong
authors: Y
authors: Zhao
authors: Chunhua
authors: C
authors: Han
authors: Junwei
authors: J
authors: Yang
authors: Jie
authors: J
authors: Su
authors: Xiaoming
authors: X
authors: Xu
authors: Shuo
authors: S
authors: Li
authors: Lin
authors: L
authors: Xu
authors: Ruopian
authors: R
authors: Fang
authors: Hong
authors: H
authors: Jiang
authors: Xiaodong
authors: X
authors: Zou
authors: Bo
authors: B
authors: Song
authors: Liqiang
authors: L
authors: Mai
authors: Qingjie
authors: Q
authors: Zhang
keywords: Alkali metal ion intercalation; ab initio calculations; metal oxide nanowire cathodes; rotation electron diffraction; synergistic stabilizing effect