Conduction with fast Li ion conductivity at room temperature is a major challenge for the development of all solid-state Li-ion batteries. Herein, we demonstrate a novel room-temperature ultrafast Li-ion conductor, lithium borohydride ammonia borane complexes ((LiBH₄)_x·AB). The incorporation of AB into the LiBH₄ structure intrinsically increases the cell volume and decreases the volume density of Li ion, which substantially facilitates the Li-ion conduction. The LiBH₄·AB complex delivers up to 4.04 × 10^–4 S cm^–1 of ion conductivity at 25 °C with nearly negligible electron conductivity. The Li-ion transference number is higher than 0.999 at 40 °C. The room-temperature Li-ion conductivity obtained is largely superior to other LiBH₄-based solid-state electrolytes reported previously under identical conditions. Moreover, the ultrafast Li-ion conduction remains stable upon heating and cooling cycling (18–55 °C). Ab initio molecular dynamics simulations display a kind of 1D Li diffusion channel along the b direction in the LiBH₄·AB structure, which offers a much lower activation energy barrier (0.12 eV), consequently enabling superior Li-ion conductivity at room temperature.

中文翻译：

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在硼氢化锂结构中引入氨硼烷基团可实现固态电池在室温下超快的锂离子电导率

在室温下具有快速锂离子电导率的导电性是所有固态锂离子电池发展的主要挑战。在这里，我们演示了一种新型的室温超快锂离子导体，硼氢化锂氨硼烷络合物（（LiBH ₄）_x ·AB）。AB掺入LiBH ₄结构中本质上增加了细胞体积并降低了Li离子的体积密度，这实质上促进了Li离子的传导。LiBH ₄ ·AB复合物可提供最高4.04×10 ^–4 S cm ^–1离子电导率在25°C时几乎可以忽略不计。在40°C下，锂离子迁移数高于0.999。在相同条件下，获得的室温锂离子电导率大大优于先前报道的其他基于LiBH ₄的固态电解质。此外，超快的锂离子传导在加热和冷却循环（18–55°C）时保持稳定。从头算分子动力学模拟显示了一种沿LiBH ₄ ·AB结构中b方向的一维Li扩散通道，该通道提供了低得多的活化能垒（0.12 eV），因此在室温下具有优异的锂离子传导性。