The resurgence of interest in sodium-ion batteries (SIBs) is largely driven by their natural abundance and favourable cost, apart from their comparable electrochemical performance when compared with lithium-ion batteries (LIBs). The uneven geographic distribution of the raw materials required for LIBs has also contributed to this. The solid-state electrolyte (SSE) is typically one of the vital components for energy storage in SIBs and for achieving high electrochemical performances. SSEs are preferred over liquid electrolytes primarily due to their enhanced safety and stability, apart from the option of achieving higher energy density. A single sodium-ion selective conductor minimises dendrite formation and cell polarisation, among many other benefits over binary ionic conductors in battery operation. Here, we demonstrate the first example of a sulfonated supramolecular organic two-dimensional (2D) nanosheet as a novel class of single sodium-ion conductors prepared from the self-assembly of a functionalised guanidinium ion (AD-1). Solvent-assisted exfoliation of the bulk powder in water yielded nanosheet morphology, whereas nanotube morphology was achieved in isopropanol (IPA). In contrast, self-assembly with systematic water/IPA solvent ratio variations produced marigold, sunflower, and nanorod morphologies. Thermodynamic parameters, crystallinity, elemental composition, and varying natures of hydrogen bonding in five distinct morphologies were determined using microscopic and spectroscopic studies. The single Na⁺ conducting properties of each morphology are correlated in terms of morphology, crystallinity, and the solvent used to achieve that specific morphology. Importantly, with high crystallinity and directional ion channels, 2D nanosheet morphology exhibits the highest single Na⁺-ion conductivity of 3.72 × 10⁻⁴ S cm⁻¹ with an activation energy of 0.28 eV, showing a moderately high Na⁺-ion transference number of 0.83 at room temperature without incorporating any additional sodium salts and organic solvents. This report is believed to be the first to show the significance of nanostructure morphologies in achieving high single-Na⁺-ion transport.

中文翻译：

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用于高效单钠离子传导的自组装胍衍生物的二维有机纳米片：合理化形态编辑和离子传导


人们对钠离子电池（SIB）的兴趣重新燃起，很大程度上是由于其自然丰富性和有利的成本，以及与锂离子电池（LIB）相比具有可比的电化学性能。锂离子电池所需原材料的地理分布不均匀也是造成这种情况的原因之一。固态电解质（SSE）通常是SIB中储能和实现高电化学性能的重要组成部分之一。 SSE 优于液体电解质，主要是因为它们具有更高的安全性和稳定性，此外还可以实现更高的能量密度。与二元离子导体相比，单一钠离子选择性导体在电池运行中具有许多其他优点，可最大程度地减少枝晶形成和电池极化。在这里，我们展示了磺化超分子有机二维（2D）纳米片的第一个例子，它是一种新型的单钠离子导体，由功能化胍离子（AD-1）的自组装制备而成。水中的散装粉末经溶剂辅助剥离产生纳米片形态，而纳米管形态是在异丙醇（IPA）中实现的。相比之下，采用系统的水/异丙醇溶剂比例变化的自组装产生了万寿菊、向日葵和纳米棒形态。使用显微镜和光谱研究确定了五种不同形态的热力学参数、结晶度、元素组成和氢键的不同性质。每种形态的单一Na ⁺导电特性在形态、结晶度和用于实现该特定形态的溶剂方面是相关的。 重要的是，由于具有高结晶度和定向离子通道，二维纳米片形态表现出最高的单Na ⁺离子电导率，为3.72 × 10 ^-4 S cm ^-1 ，活化能为0.28 eV，表现出较高的Na ⁺离子迁移数在室温下不加入任何额外的钠盐和有机溶剂的情况下，其分子量为0.83。该报告被认为是第一个展示纳米结构形态在实现高单Na ⁺离子传输方面的重要性的报告。