An Anode‐Free Potassium‐Metal Battery Enabled by a Directly Grown Graphene‐Modulated Aluminum Current Collector

• Published in: Advanced materials (Weinheim) 2022-07, Vol.34 (29), p.e2202902-n/a
• Main Authors: Zhao, Yu, Liu, Bingzhi, Yi, Yuyang, Lian, Xueyu, Wang, Menglei, Li, Shuo, Yang, Xianzhong, Sun, Jingyu
• Format: Article
• Language: English
• Subjects: Adhesive strength; Aluminum; aluminum foil; Anodes; anode‐free potassium‐metal batteries; Chemical vapor deposition; Collectors; current collectors; direct growth; Energy storage; Graphene; Materials science; Metal foils; Plating; Potassium; Storage batteries; Surface energy
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202202902

Potassium (K)‐metal batteries have emerged as a promising energy‐storage device owing to abundant K resources. An anode‐free architecture that bypasses the need for anode host materials can deliver an elevated energy density. However, the poor efficiency of K plating/stripping on potassiophobic anode current collectors results in rapid K inventory loss and a short cycle life. Herein, commercial Al foils are decorated with an ultrathin graphene‐modified layer (Al@G) through roll‐to‐roll plasma‐enhanced chemical vapor deposition. By harnessing strong adhesion (10.52 N m−1) and a high surface energy (66.6 mJ m−2), the designed Al@G structure ensures a highly smooth and ordered K plating/stripping process. Consequently, during K‐metal plating/stripping, Al@G can operate at a current density of up to 4.0 mA cm−2 and cyclic capacity of up to 4.0 mAh cm−2, with an ultralong lifespan of up to 1000 h at 0.5 mA cm−2 and stable cycling of up to 750 h under periodic current fluctuations of 0.1–2.0 mA cm−2. In addition, a novel anode‐free K‐metal full‐cell prototype enabled by Al@G anode current collectors is constructed, demonstrating ameliorative cyclic stability. Benefiting from a plasma‐enhanced chemical vapor deposition setup integrated with a roll‐to‐roll configuration, a commercial Al foil is elaborately decorated with a graphene layer with strong adhesion and high surface energy, which enables a smooth and highly reversible K plating/stripping process. An anode‐free K‐metal full‐cell using the as‐synthesized substrate as the anode current collector displays improved performance.