纳米支架孔隙率和表面化学性质对LiBH4-LiNH2 /金属氧化物纳米复合材料锂离子电导率的影响,Journal of Materials Chemistry A

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纳米支架孔隙率和表面化学性质对LiBH4-LiNH2 /金属氧化物纳米复合材料锂离子电导率的影响
Journal of Materials Chemistry A ( IF 10.7 ) Pub Date : 2020-09-14 , DOI: 10.1039/d0ta07600g
Laura M. de Kort _{1,

2,

3,

4} , Justine Harmel _{1,

2,

3,

4} , Petra E. de Jongh _{1,

2,

3,

4} , Peter Ngene _{1,

2,

3,

4}

Affiliation

固态电解质对于实现容量更安全的电池至关重要。锂基复合氢化物（例如LiBH _4）作为固态电解质显示出令人鼓舞的特性。但是，增加其低室温电导率（LiBH ₄为10 ^-8 S cm ^-1）是应用的先决条件。BH的局部离子取代₄^-与NH ₂^-，随后在孔氧化支架nanoconfinement增加电导率为5×10 ^-4小号厘米^-1。在这里，我们显示了LiBH ₄ -LiNH ₂的电导率/金属氧化物纳米复合材料受支架材料的化学和物理性质的强烈影响。通过调节表面化学性质和孔结构，在室温下电导率可以改变三个数量级。出乎意料的是，即使观察到支架表面化学的显着影响，纳米复合材料的电导率很大程度上由支架孔体积决定。这与纳米限制的纯LiBH ₄形成对比，后者的电导率由中孔支架的化学性质决定。对于纳米受限的LiBH ₄ –LiNH ₂因此，电导率的提高归因于支架孔内部高导电相的稳定，而不是如纳米约束LiBH ₄所观察到的在氧化物/氢化物界面处形成导电界面层。这些发现可能适用于其他阳离子和阴离子取代的纳米复合材料，并提供有用的工具来开发具有出色的离子电导率的新型固态电解质。

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The effect of nanoscaffold porosity and surface chemistry on the Li-ion conductivity of LiBH4–LiNH2/metal oxide nanocomposites

Solid-state electrolytes are crucial for the realization of safer batteries with improved capacity. Lithium-based complex hydrides, for instance LiBH₄, display promising characteristics as solid-state electrolytes. However, increasing their low room temperature conductivity (10⁻⁸ S cm⁻¹ for LiBH₄) is a prerequisite for application. Partial ionic substitution of BH₄⁻ with NH₂⁻ followed by nanoconfinement in mesoporous oxide scaffolds increases the conductivity to 5 × 10⁻⁴ S cm⁻¹. Here, we show that the conductivity of LiBH₄–LiNH₂/metal oxide nanocomposites is strongly influenced by the chemical and physical nature of the scaffold material. By tuning both the surface chemistry and the pore structure, the conductivity can be varied by three orders of magnitude at room temperature. Unexpectedly, even though a significant influence of the scaffold surface chemistry is observed, the nanocomposite conductivity is largely dictated by the scaffold pore volume. This is in contrast to nanoconfined pure LiBH₄, where the conductivity is governed by the chemical nature of the mesoporous scaffold. For nanoconfined LiBH₄–LiNH₂, the conductivity improvement is attributed to stabilization of a highly conductive phase inside the scaffold pores, rather than the formation of a conductive interfacial layer at the oxide/hydride interface as observed for nanoconfined LiBH₄. These findings could be applicable to other cation- and anion-substituted nanocomposites and provide a useful tool to develop novel solid-state electrolytes with excellent ionic conductivities.

更新日期：2020-10-13

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