Researchers designed a nonflammable phosphate electrolyte for potassium-ion batteries that maintains stability across both electrodes, according to a peer-reviewed study published in Nature Communications.
Conventional nonflammable electrolytes often suffer from poor electrode compatibility caused by strong solvation and excessive free solvent molecules. To address this limitation, the team developed a molecular design strategy using tri(2-butoxyethyl) phosphate. By attaching lengthened functionalized side-chains to the phosphate backbone, the molecule achieves multi-site chelation through synergistic interactions between its ether oxygen (C-O-C) and phosphoryl (P=O) groups.
The enlarged molecular structure increases the anion-to-solvent ratio in the electrolyte. This structural shift promotes the formation of stable electrode-electrolyte interphases on both positive and negative battery electrodes.
Testing demonstrated high electrochemical stability across multiple configurations. A graphite negative electrode using the tailored electrolyte retained 92.7% of its capacity after 800 cycles at 100 mA g−1. A 4.2 V Prussian blue positive electrode recorded 88.6% capacity retention after 3,200 cycles at 100 mA g−1. When assembled into a graphite||Prussian blue full cell, the system maintained 80.3% capacity retention after 1,500 cycles at 500 mA g−1.
Jie Wen and Maoting Xia contributed equally as lead authors on the paper. The research team included scientists from Hunan University, Clemson University, Central South University, Hunan University of Technology and Business, and the Yuelushan Center for Industrial Innovation. Project funding came from the National Natural Science Foundation of China, the China Postdoctoral Science Foundation, the Program of Top Talent for Hunan Province, and the R. A. Bowen Endowed Professorship funds at Clemson University.
