Adaptive Cation Pillar Effects Achieving High Capacity in Li‐Rich Layered Oxide, Li2MnO3‐LiMeO2 (Me = Ni, Co, Mn). Issue 42 (2nd September 2022)

• Record Type: Journal Article
• Authors: Hiroi, Satoshi; Oishi, Masatsugu; Ohara, Koji; Shimoda, Keiji; Kabutan, Daiki; Uchimoto, Yoshiharu
• Is Part Of: Small. Volume 18:Issue 42(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-09-02
• Subjects: adaptive pillars -- cation mixing -- Li‐rich layered oxides -- lithium‐ion batteries -- pair distribution function -- positive electrode materials -- X‐ray total scattering measurements; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.202203412
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: Intensive research is underway to further enhance the performance of lithium‐ion batteries (LIBs). To increase the capacity of positive electrode materials, Li‐rich layered oxides (LLO) are attracting attention but have not yet been put to practical use. The structural mechanisms through which LLO materials exhibit higher capacity than conventional materials remain unclear because their disordered phases make it difficult to obtain structural information by conventional analysis. The X‐ray total scattering analysis reveals a disordered structure consisting of metal ions in octahedral and tetrahedral sites of Li layers as a result of cation mixing after the extraction of Li ions. Metal ions in octahedral sites act as rigid pillars. The metal ions move to the tetrahedral site of the Li layer, which functions as a Li‐layer pillar during Li extraction, and returns to the metal site during Li insertion, facilitating Li diffusion as an adaptive pillar. Adaptive pillars are the specific structural features that differ from those of the conventional layered materials, and their effects are responsible for the high capacity of LLO materials. An essential understanding of the pillar effects will contribute to design guidelines for intercalation‐type positive electrodes for next‐generation LIBs. Abstract : Variations of the atomic structure of Li‐rich layered oxide (LLO) positive electrode by charge–discharge cycles are unveiled. Two kinds of pillars supporting vacant Li layers exist in the layered structure formed by the charge process. A promising way to unveil the mechanism behind the enhanced electrochemical properties is to understand the role of transition metals in the LLO material.