All-solid-state lithium batteries (ASSLBs) with non-flammable solid-state electrolytes offer high energy density and enhanced safety. However, their energy densities are greatly limited by low-capacity and low-ionic-conductivity oxide cathode materials, typically relying on the intercalation-deintercalation mechanism with a catholyte content of 15~30 wt.%. Here we introduce the LixFeXx+2 (X=Cl, Br) families as high-capacity and high-ionic-conductivity alternatives, operating via a 3 mol e- transfer intercalation-conversion coupling reaction. Notably, the catholyte-free ASSLBs using 95 wt.% LiFeCl3 active material delivers a remarkable capacity of 446 mAh g-1 and a high energy density of 912 Wh kg-1, which surpasses most oxide cathode materials. Of particular interest is the formation of amorphous Fe during the conversion process. The amorphous Fe exhibits high activity, catalyzing the conversion of LiX back to LixFeXx+2, which proves instrumental in realizing reversible intercalation-conversion reactions. These halide cathode materials represent a significant advancement towards high-energy-density ASSLBs.

中文翻译：

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基于全固态锂电池插层-转换反应的多电子转移卤化物正极材料


采用不易燃固态电解质的全固态锂电池 （ASSLB） 提供高能量密度和增强的安全性。然而，它们的能量密度受到低容量和低离子电导率氧化物正极材料的极大限制，通常依赖于阴极化合物含量为 15~30 wt.% 的插层-脱嵌机制。在这里，我们介绍了 LixFeXx+2 （X=Cl， Br） 系列作为高容量和高离子电导率的替代品，通过 3 mol e-转移插层-转化偶联反应运行。值得注意的是，使用 95 wt.% LiFeCl3 活性材料的无阴极 ASSLB 可提供 446 mAh g-1 的显着容量和 912 Wh kg-1 的高能量密度，超过了大多数氧化物正极材料。特别令人感兴趣的是在转化过程中形成非晶态 Fe。无定形 Fe 表现出高活性，催化 LiX 转化回 LixFeXx+2，这被证明有助于实现可逆的插层-转化反应。这些卤化物正极材料代表了高能量密度 ASSLB 的重大进步。