The development of high-performance potassium ion battery (KIB) electrodes requires a nanoengineering design aimed at optimizing the construction of active material/buffer material nanocomposites. These nanocomposites will alleviate the stress resulting from large volume changes induced by K⁺ ion insertion/extraction and enhance the electrical and ion conductivity. We report the synthesis of phosphorus-embedded ultrasmall bismuth–antimony nanocrystals (Bi_xSb_1–x@P, (0 ≤ x ≤ 1)) for KIB anodes via a facile solution precipitation at room temperature. Bi_xSb_1–x@P nanocomposites can enhance potassiation–depotassiation reactions with K⁺ ions, owing to several attributes. First, by adjusting the feed ratios of the Bi/Sb reactants, the composition of Bi_xSb_1–x nanocrystals can be systematically tuned for the best KIB anode performance. Second, extremely small (diameter ≈ 3 nm) Bi_xSb_1–x nanocrystals were obtained after cycling and were fixed firmly inside the P matrix. These nanocrystals were effective in buffering the large volume change and preventing the collapse of the electrode. Third, the P matrix served as a good medium for both electron and K⁺ ion transport to enable rapid charge and discharge processes. Fourth, thin and stable solid electrolyte interface (SEI) layers that formed on the surface of the cycled Bi_xSb_1–x@P electrodes resulted in low resistance of the overall battery electrode. Lastly, in situ X-ray diffraction analysis of K⁺ ion insertion/extraction into/from the Bi_xSb_1–x@P electrodes revealed that the potassium storage mechanism involves a simple, direct, and reversible reaction pathway: (Bi, Sb) ↔ K(Bi, Sb) ↔ K₃(Bi, Sb). Therefore, electrodes with the optimized composition, i.e., Bi_0.5Sb_0.5@P, exhibited excellent electrochemical performance (in terms of specific capacity, rate capacities, and cycling stability) as KIB anodes. Bi_0.5Sb_0.5@P anodes retained specific capacities of 295.4 mA h g^–1 at 500 mA g^–1 and 339.1 mA h g^–1 at 1 A g^–1 after 800 and 550 cycles, respectively. Furthermore, a capacity of 258.5 mA h g^–1 even at 6.5 A g^–1 revealed the outstanding rate capability of the Sb-based KIB anodes. Proof-of-concept KIBs utilizing Bi_0.5Sb_0.5@P as an anode and PTCDA (perylenetetracarboxylic dianhydride) as a cathode were used to demonstrate the applicability of Bi_0.5Sb_0.5@P electrodes to full cells. This study shows that Bi_xSb_1–x@P nanocomposites are promising carbon-free anode materials for KIB anodes and are readily compatible with the commercial slurry-coating process applied in the battery manufacturing industry.

中文翻译：

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Bi-Sb纳米晶体作为高性能钾离子电池电极嵌入磷中。

高性能钾离子电池（KIB）电极的开发需要进行纳米工程设计，以优化活性材料/缓冲材料纳米复合材料的结构。这些纳米复合材料将缓解由K ⁺离子插入/引出引起的大体积变化所引起的应力，并增强电导率和离子电导率。我们报告的磷嵌入超小型铋-锑的纳米晶体合成的（Bi _X Sb的_{1- X} @P，（0≤ X ≤1）），用于KIB阳极经由一个浅显的溶液在室温下沉淀。Bi _x Sb _{1– x} @P纳米复合材料可增强钾的钾离子-钾离子的反作用⁺离子，由于几个属性。首先，通过调节Bi / Sb反应物的进料比，可以系统地调节Bi _x Sb _{1– x}纳米晶体的组成，以获得最佳的KIB阳极性能。其次，循环后获得了极小的（直径≈3 nm）Bi _x Sb _{1– x}纳米晶体，并牢固地固定在P基质内部。这些纳米晶体可有效地缓冲大体积变化并防止电极塌陷。第三，P基质是电子和K ⁺的良好介质离子传输以实现快速充电和放电过程。第四，在循环的Bi _x Sb _{1– x} @P电极表面上形成的薄而稳定的固体电解质界面（SEI）层导致整个电池电极的电阻较低。最后，对K ⁺离子从Bi _x Sb _{1– x} @P电极中插入/抽出的原位X射线衍射分析表明，钾的存储机制涉及简单，直接和可逆的反应途径： ）↔K（Bi，Sb）↔K ₃（Bi，Sb）。因此，电极具有最佳的组成，即Bi _0.5 Sb _0.5P作为KIB阳极表现出出色的电化学性能（就比容量，倍率容量和循环稳定性而言）。Bi _0.5 Sb _0.5 @P阳极在800和550次循环后，在500 mA g ^–1时的比容量分别为295.4 mA hg ^–1和1 A g ^–1时的339.1 mA hg ^–1。此外，即使在6.5 A g ^–1时，容量仍为258.5 mA hg ^–1，这表明基于Sb的KIB阳极具有出色的倍率性能。以Bi _0.5 Sb _0.5 @P为阳极并以PTCDA（per四羧酸二酐）为阴极的概念验证KIB用于证明Bi的适用性_0.5 Sb _0.5 @P电极至满电池。这项研究表明，Bi _x Sb _{1– x} @P纳米复合材料是用于KIB阳极的有前途的无碳阳极材料，并且很容易与电池制造工业中应用的商业浆料涂覆工艺兼容。