With high theoretical capacity and applicable operating voltage, layered transition metal oxides are potential cathodes for potassium-ion batteries (PIBs). However, a K⁺/vacancy ordered structure in these oxides limits the K⁺ transport kinetics and storage sites so that the PIBs still have poor rate performance and low achievable capacity. Here, to effectively resolve the problem, a K⁺/vacancy disordered P3-type structure is designed and synthesized by simply modulating the K⁺ contents in Mn/Ni-based layered oxides. The effect of the K⁺ contents in a series of K_xMn_0.7Ni_0.3O₂ (x = 0.4–0.7) oxides has been systematically studied and it is found that while the K⁺/vacancy ordered superstructure is stable at low K⁺ content (x < 0.6), a complete K⁺/vacancy disordered structure forms at high K⁺ content (x > 0.6), evidenced by selected area electron diffraction and voltage plateaus in the charge/discharge curves. The K⁺/vacancy disordered K_0.7Mn_0.7Ni_0.3O₂ exhibits much better rate performance and higher discharge capacity, compared to the K⁺/vacancy ordered K_0.4Mn_0.7Ni_0.3O₂. Molecular dynamic simulations confirm that the K⁺/vacancy disordered structure possesses interconnected continuous channels for K⁺ diffusion and more active storage sites. This discovery sheds light on rational design of K⁺/vacancy disordered layered oxide cathodes for next-generation high-performance PIBs.

中文翻译：

---

适用于高倍率和高容量钾离子电池的K +调制K + /空位无序层状氧化物

具有较高的理论容量和适用的工作电压，层状过渡金属氧化物是钾离子电池（PIB）的潜在阴极。但是，这些氧化物中的K ⁺ /空位有序结构限制了K ^+的传输动力学和存储位点，因此PIB的速率性能仍然很差，可达到的容量较低。这里，为了有效地解决该问题，通过简单地调节Mn / Ni基层状氧化物中的K ⁺含量，设计并合成了K ⁺ /空位无序的P3型结构。的K个效果⁺内容在一系列的K _X的Mn _0.7镍_0.3 ø ₂（X= 0.4–0.7）氧化物已经过系统地研究，发现虽然K ⁺ /空位有序的上层结构在低K ⁺含量下（x <0.6）是稳定的，但完整的K ⁺ /空位无序结构在高K ⁺含量下形成（x > 0.6），由充电/放电曲线中的选定区域电子衍射和电压平稳期证明。与K ⁺ /空位有序K _0.4 Mn _0.7相比，K ⁺ /空位无序K _0.7 Mn _0.7 Ni _0.3 O ₂表现出更好的倍率性能和更高的放电容量。Ni _0.3 O ₂。分子动力学模拟证实，K ⁺ /空位无序结构具有互连的K ⁺扩散连续通道和更活跃的存储位点。这一发现为下一代高性能PIB的K ⁺ /空位无序分层氧化物阴极的合理设计提供了启示。