Abstract

The dendrite growth of Li anodes severely degrades the performance of lithium-oxygen (Li-O₂) batteries. Recently, hybrid solid electrolyte (HSE) has been regarded as one of the most promising routes to tackle this problem. However, before this is realized, the HSE needs to simultaneously satisfy contradictory requirements of high modulus and even, flexible contact with Li anode, while ensuring uniform Li⁺ distribution. To tackle this complex dilemma, here, an HSE with rigid Li_1.5Al_0.5Ge_1.5(PO₄)₃ (LAGP) core@ultrathin flexible poly (vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) shell interface has been developed. The introduced large amount of nanometer-sized LAGP cores can not only act as structural enhancer to achieve high Young's modulus but can also construct Li⁺ diffusion network to homogenize Li⁺ distribution. The ultrathin flexible PVDF-HFP shell provides soft and stable contact between the rigid core and Li metal without affecting the Li⁺ distribution, meanwhile suppressing the reduction of LAGP induced by direct contact with Li metal. Thanks to these advantages, this ingenious HSE with ultra-high Young's modulus of 25 GPa endows dendrite-free Li deposition even at a deposition capacity of 23.6 mAh. Moreover, with the successful inhibition of Li dendrites, the HSE-based quasi-solid-state Li-O₂ battery delivers a long cycling stability of 146 cycles, which is more than three times that of gel polymer electrolyte-based Li-O₂ battery. This new insight may serve as a starting point for further designing of HSE in Li-O₂ batteries, and can also be extended to various battery systems such as sodium-oxygen batteries.

中文翻译：

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用于高性能准固态锂氧电池的无枝晶锂负极混合固体电解质

摘要

锂负极的枝晶生长严重降低了锂氧（Li-O ₂）电池的性能。最近，混合固体电解质（HSE）被认为是解决这一问题的最有希望的途径之一。然而，在此之前，HSE需要同时满足高模量和与锂负极均匀、灵活接触的矛盾要求，同时确保锂^离子分布均匀。为了解决这个复杂的难题，这里采用了具有刚性 Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃的 HSE(LAGP) core@ultrathin 柔性聚（偏二氟乙烯-六氟丙烯）（PVDF-HFP）壳界面已经开发完成。引入的大量纳米级 LAGP 核不仅可以作为结构增强剂来实现高杨氏模量，还可以构建 Li ⁺扩散网络以均匀化 Li ⁺分布。超薄柔性 PVDF-HFP 外壳在刚性核与锂金属之间提供柔软稳定的接触，而不会影响锂⁺分布，同时抑制与锂金属直接接触引起的 LAGP 还原。由于这些优势，这种具有 25 GPa 超高杨氏模量的巧妙 HSE 即使在 23.6 mAh 的沉积容量下也能实现无枝晶的锂沉积。此外，通过成功抑制锂枝晶，基于HSE的准固态Li-O ₂电池具有146次循环的长循环稳定性，是基于凝胶聚合物电解质的Li-O ₂电池的三倍以上电池。这一新见解可以作为进一步设计 Li-O ₂电池中 HSE 的起点，也可以扩展到各种电池系统，如钠氧电池。