Facile Synthesis of Potassium Decahydrido‐Monocarba‐<i>closo</i>‐Decaborate Imidazole Complex Electrolyte for All‐Solid‐State Potassium Metal Batteries
Zhiwei Lu, Zhiwei Lu, Pengtao Qiu, Hanyu Zhai, Guoguo Zhang, Xinwei Chen, Xinwei Chen, Zhansheng Lu, Zhansheng Lu, Yiying Wu, Xuenian Chen, Xuenian Chen
Abstract
Abstract All‐solid‐state potassium metal batteries have caught increasing interest owing to their abundance, cost‐effectiveness, and high energy/power density. However, their development is generally constrained by the lack of suitable solid‐state electrolytes. Herein, we report a new complex KCB 9 H 10 ⋅ 2C 3 H 4 N 2 , synthesized by grinding and heating the mixture of potassium decahydrido‐monocarba‐ closo ‐decaborate (KCB 9 H 10 ) and imidazole (C 3 H 4 N 2 ) under mild conditions, to achieve the K‐ion superionic solid‐state electrolyte. The crystal structure was revealed as an orthorhombic lattice with the space group of Pna 2 1 by FOX software. The diffusion properties for K + in the crystal structure were calculated using the climbing image nudged elastic band (CI‐NEB) method. KCB 9 H 10 ⋅ 2C 3 H 4 N 2 exhibited a high ionic conductivity of 1.3×10 −4 S cm −1 at 30 °C, four orders of magnitude higher than that of KCB 9 H 10 . This ionic conductivity is also the highest value of hydridoborate‐based K + conductors reported. Moreover, KCB 9 H 10 ⋅ 2C 3 H 4 N 2 demonstrated a K + transference number of 0.96, an electrochemical stability window of 1.2 to 3.2 V vs. K/K + , and good stability against the K metal coated by a layer of potassium imidazolate (KIm). These great performances make KCB 9 H 10 ⋅ 2C 3 H 4 N 2 a promising K‐ion solid‐state electrolyte.