We discuss here a unique flexible non‐carbonaceous layered host, namely, metal titanium niobates (M‐Ti‐niobate, M: Al³⁺, Pb²⁺, Sb³⁺, Ba²⁺, Mg²⁺), which can synergistically store both lithium ions and sodium ions via a simultaneous intercalation and alloying mechanisms. M‐Ti‐niobate is formed by ion exchange of the K⁺ ions, which are specifically located inside galleries between the layers formed by edge and corner sharing TiO₆ and NbO₆ octahedral units in the sol‐gel synthesized potassium titanium niobate (KTiNbO₅). Drastic volume changes (approximately 300–400 %) typically associated with an alloying mechanism of storage are completely tackled chemically by the unique chemical composition and structure of the M‐Ti‐niobates. The free space between the adjustable Ti/Nb octahedral layers easily accommodates the volume changes. Due to the presence of an optimum amount of multivalent alloying metal ions (50–75 % of total K⁺) in the M‐Ti‐niobate, an efficient alloying reaction takes place directly with ions and completely eliminates any form of mechanical degradation of the electroactive particles. The M‐Ti‐niobate can be cycled over a wide voltage range (as low as 0.01 V) and displays remarkably stable Li⁺ and Na⁺ ion cyclability (>2 Li⁺/Na⁺ per formula unit) for widely varying current densities over few hundreds to thousands of successive cycles. The simultaneous intercalation and alloying storage mechanisms is also studied within the density functional theory (DFT) framework. DFT expectedly shows a very small variation in the volume of Al‐titanium niobate following lithium alloying. Moreover, the theoretical investigations also conclusively support the occurrence of the alloying process of Li ions with the Al ions along with the intercalation process during discharge. The M‐Ti‐niobates studied here demonstrate a paradigm shift in chemical design of electrodes and will pave the way for the development of a multitude of improved electrodes for different battery chemistries.

中文翻译：

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插层主体中的合金：铌酸金属钛作为可充电碱性离子电池的阳极

我们在这里讨论一种独特的柔性非碳质层状主体，即金属铌酸盐（M-Ti-铌酸盐，M：Al ³⁺，Pb 2 ⁺，Sb ³⁺，Ba 2 ⁺，Mg ²⁺），它们可以协同作用。通过同时嵌入和合金化机制同时存储锂离子和钠离子。M-Ti系铌酸是由K个的离子交换形成的⁺离子，其被特别位于由边缘和角共享的TiO形成的层之间的画廊₆和NbO的_6个在溶胶-凝胶合成的钾钛铌酸八面体单元（KTiNbO ₅）。通常，通过M-Ti-铌酸盐的独特化学组成和结构，可以通过化学方法彻底解决通常与合金化存储机制相关的急剧的体积变化（大约300-400％）。可调节的Ti / Nb八面体层之间的自由空间可轻松适应体积变化。由于在M-Ti-铌酸盐中存在最佳数量的多价合金化金属离子（占总K ^+的50–75％），因此有效的合金化反应直接与离子发生，从而完全消除了金属离子的任何形式的机械降解。电活性颗粒。铌钛酸铌可以在很宽的电压范围内（低至0.01 V）循环，并显示出非常稳定的Li ⁺和Na ⁺离子循环能力（> 2 Li ⁺ / Na^+（每个公式单位⁺），可在数百到数千个连续周期中实现广泛变化的电流密度。同时在密度泛函理论（DFT）框架内研究了同时插层和合金存储机制。DFT预计在锂合金化后，铌酸钛铝的体积变化很小。此外，理论研究也最终支持了锂离子与铝离子的合金化过程以及放电过程中的插入过程的发生。此处研究的M-Ti-铌酸盐证明了电极化学设计的范式转变，将为开发用于不同电池化学性质的多种改进电极铺平道路。