Ultrastable Graphite‐Potassium Anode through Binder Chemistry

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2023-12, Vol.19 (50), p.e2302987-n/a
• Main Authors: Mao, Zhifei, Shi, Xiaojun, Zhang, Taoqiu, Zheng, Zhi, Liang, Xueying, Wang, Rui, Jin, Jun, He, Beibei, Gong, Yansheng, Wang, Huanwen
• Format: Article
• Language: English
• Subjects: Adhesive strength; anodes; binder; Electrolytes; Graphite; Nanotechnology; Polyvinyl alcohol; Potassium; potassium‐ion batteries; Rechargeable batteries; Three dimensional printing
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202302987

Graphite with abundant reserves has attracted enormous research interest as an anode of potassium‐ion batteries (PIBs) owing to its high plateau capacity of 279 mAh g−1 at ≈0.2 V in conventional carbonate electrolytes. Unfortunately, it suffers from fast capacity decay during K+ storage. Herein, an ultrastable graphite‐potassium anode is developed through binder chemistry. Polyvinyl alcohol (PVA) is utilized as a water‐soluble binder to generate a uniform and robust KF‐rich SEI film on the graphite surface, which can not only inhibit the electrolyte decomposition, but also withstand large volume expansion during K+‐insertion. Compared to the PVDF as binder, PVA‐based graphite anode can operate for over 2000 cycles (running time of 406 days at C/3) with 97% capacity retention in KPF6‐based electrolytes. The initial Coulombic efficiency (ICE) of graphite anode is as high as 81.6% using PVA as the binder, higher than that of PVDF (40.1%). Benefiting from the strong adhesion ability of PVA, a graphite||fluorophosphate K‐ion full battery is further built through 3D printing, which achieves a record‐high areal energy of 8.9 mWh cm−2 at a total mass loading of 38 mg cm−2. These results demonstrate the important role of binder in developing high‐performance PIBs. Polyvinyl alcohol is utilized as a water‐soluble binder to generate an KF‐rich SEI film on graphite anode of potassium‐ion batteries, which exhibit excellent cycling stability (97% capacity retention after 2000 cycles at 1/3 C, running time of 406 days) and a high ICE of 81.6% in the 0.8 m KPF6/EC/DEC electrolyte.