In Situ Ions Induced Formation of KxF‐Rich SEI Layers toward Ultrastable Life of Potassium‐Ion Batteries

• DOI: 10.1002/adma.202401943
• Publication Date: 2024-05-20T23:29:25Z
• Authors: Tianqi Wang; Xin He; Min Zhou; Jing Ning; Shengling Cao; Manlin Chen; Haomiao Li; Wei Wang; Kangli Wang; Kai Jiang
• Keywords: 02 engineering and technology; 0210 nano-technology

AbstractEngineering F‐rich solid electrolyte interphase (SEI) layers is regarded as an effective strategy to enable the long‐term cycling stability of potassium‐ion batteries (KIBs). However, in the conventional KPF6 carbonate electrolytes, it is challenging to form F‐containing SEI layers due to the inability of KPF6 to decompose into KxF. Herein, AlCl3 is employed as a novel additive to change the chemical environment of the KPF6 carbonate electrolyte. First, due to the large charge‐to‐radius ratio of Al3+, the Al‐containing groups in the electrolyte can easily capture F from PF6− and accelerate the formation of KxF in SEI layer. In addition, AlCl3 also reacts with trace H2O or solvents in the electrolytes to form Al2O3, which can further act as a HF scavenger. Upon incorporating AlCl3 into conventional KPF6 carbonate electrolyte, the hard carbon (HC) anode exhibits an ultra‐long lifespan of 10000 cycles with a high coulombic efficiency of ≈100%. When coupled with perylene‐3,4,9,10‐tetracarboxylic dianhydride (PTCDA), the full cell exhibits a high capacity retention of 81% after 360 cycles‐significantly outperforming cells using conventional electrolytes. This research paves new avenues for advancing electrolyte engineering towards developing durable batteries tailored for large‐scale energy storage applications.