Orthorhombic K3V3(PO4)4: A low-temperature cathode material for potassium-ion batteries

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2024-07, Vol.491, p.151968, Article 151968
• Main Authors: Luo, Rui-Jie, Du, Chong-Yu, Ma, Cui, Zeng, Jie, Xu, Xuan, Qian, Zhe, Mei, Zhe, Zhou, Zi-Ting, Zhu, Ze-Yu, Zhou, Yong-Ning
• Format: Article
• Language: English
• Subjects: Cathode materials; Orthorhombic; Polyanionic; Potassium-ion batteries
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2024.151968

•A combination of high-energy ball milling and solid-state synthesis was used to prepare the K3V3(PO4)4/C cathode material.•K3V3(PO4)4/C exhibits promising low-temperature cycle performance.•The structural evolution of K3V3(PO4)4 was revealed using synchrotron in situ XRD techniques.•It is found that V3+/V4+ redox dominates the charge compensation in K3V3(PO4)4/C during cycling. Potassium-ion battery has been considered as a promising energy storage device with low cost and high sustainability. However, its low-temperature performance is always poor due to the large size of K+ ions and poor ion transportation capability under low temperature. In this work, a carbon-coated orthorhombic K3V3(PO4)4/C cathode material for potassium-ion batteries is developed with promising low-temperature cycle performance. At −10 °C, K3V3(PO4)4/C retains a reversible capacity of 52.2 mAh/g for 1400 cycles at a current density of 100 mA g−1. The superior low-temperature performance is attributed to its open framework structure, which provides three-dimension channels for K-ion transportation. It is revealed that V3+/V4+ redox dominates the charge compensation in K3V3(PO4)4/C during charge and discharge processes. Carbon coating can not only reduce the charge transfer resistance of the electrode and prevent electrode cracking, but also helps to the formation of CF3-rich interfaces between the cathode and electrolyte, ensuring high interfacial stability of K3V3(PO4)4/C during cycling.