Building K–C Anode with Ultrahigh Self‐Diffusion Coefficient for Solid State Potassium Metal Batteries Operating at −20 to 120 °C

• Published in: Advanced materials (Weinheim) Vol. 35; no. 16; pp. e2209833 - n/a
• Main Authors: Wu, Jian‐Fang, Zhou, Wang, Wang, Zixing, Wang, Wei‐Wei, Lan, Xuexia, Yan, Hanghang, Shi, Tuo, Hu, Renzong, Cui, Xiangyang, Xu, Chaohe, He, Xiangming, Mao, Bing‐Wei, Zhang, Tao, Liu, Jilei
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.04.2023
• Subjects: Allotropy; Aluminum oxide; Anodes; composite potassium anodes; Current density; Diffusion coefficient; diffusion kinetics; Electrochemical analysis; Electrolytic cells; Energy storage; High current; high‐temperature stability; interfacial stability; Kinetics; Melting points; Pigments; Potassium; Solid electrolytes; Solid state; solid state potassium batteries; Thermal stability; diffusion kinetics; high-temperature stability; interfacial stability; solid state potassium batteries; composite potassium anodes
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202209833

Solid state potassium (K) metal batteries are intriguing in grid‐scale energy storage, benefiting from the low cost, safety, and high energy density. However, their practical applications are impeded by poor K/solid electrolyte (SE) interfacial contact and limited capacity caused by the low K self‐diffusion coefficient, dendrite growth, and intrinsically low melting point/soft features of metallic K. Herein, a fused‐modeling strategy using potassiophilic carbon allotropes molted with K is demonstrated that can enhance the electrochemical performance/stability of the system via promoting K diffusion kinetics (2.37 × 10−8 cm2 s−1), creating a low interfacial resistance (≈1.3 Ω cm2), suppressing dendrite growth, and maintaining mechanical/thermal stability at 200 °C. A homogeneous/stable K stripping/plating is consequently implemented with a high current density of 2.8 mA cm−2 (at 25 °C) and a record‐high areal capacity of 11.86 mAh cm−2 (at 0.2 mA cm−2). The enhanced K diffusion kinetics contribute to sustaining intimate interfacial contact, stabilizing the stripping/plating at high current densities. Full cells coupling ultrathin K–C composite anodes (≈50 µm) with Prussian blue cathodes and β/β″‐Al2O3 SEs deliver a high energy density of 389 Wh kg−1 with a retention of 94.4% after 150 cycles and fantastic performances at −20 to 120 °C. An ultrathin K–10% reduced graphene oxide anode is constructed, delivering promoted K diffusion kinetics and mechanical/thermal stability at 200 °C, which creates an interfacial resistance (≈1.3 Ω cm2) with a current density of 2.8 mA cm−2 at 25 °C and an areal capacity of 11.86 mAh cm−2, enabling solid state potassium metal batteries operating at −20 to 120 °C.