Scalable Water‐Based Production of Highly Conductive 2D Nanosheets with Ultrahigh Volumetric Capacitance and Rate Capability

• Published in: Advanced energy materials 2018-06, Vol.8 (18), p.n/a
• Main Authors: Jeon, Hyeonyeol, Jeong, Jae‐Min, Kang, Heon Gyu, Kim, Hyung‐Jin, Park, Jeyoung, Kim, Do Hyun, Jung, Young Mee, Hwang, Sung Yeon, Han, Young‐Kyu, Choi, Bong Gill
• Format: Article
• Language: English
• Subjects: 2D nanosheets; Capacitance; Electric vehicles; Electrolytes; first‐principles calculations; fluid dynamic exfoliation; Flux density; Ionic liquids; Molybdenum disulfide; Nanosheets; Nonaqueous electrolytes; Packing density; Sheets; supercapacitors
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.201800227

Highly conductive and ultrathin 2D nanosheets are of importance for the development of portable electronics and electric vehicles. However, scalable production and rational design for highly electronic and ionic conductive 2D nanosheets still remain a challenge. Herein, an industrially adoptable fluid dynamic exfoliation process is reported to produce large quantities of ionic liquid (IL)‐functionalized metallic phase MoS2 (m‐MoS2) and defect‐free graphene (Gr) sheets. Hybrid 2D–2D layered films are also fabricated by incorporating Gr sheets into compact m‐MoS2 films. The incorporated IL functionalities and Gr sheets prevent aggregation and restacking of the m‐MoS2 sheets, thereby creating efficient and rapid ion and electron pathways in the hybrid films. The hybrid film with a high packing density of 2.02 g cm−3 has an outstanding volumetric capacitance of 1430.5 F cm−3 at 1 A g−1 and an extremely high rate capability of 80% retention at 1000 A g−1. The flexible supercapacitor assembled using a polymer‐gel electrolyte exhibits excellent resilience to harsh electrochemical and mechanical conditions while maintaining an impressive rate performance and long cycle life. Successful achievement of an ultrahigh volumetric energy density (1.14 W h cm−3) using an organic electrolyte with a wide cell voltage of ≈3.5 V is demonstrated. Highly conductive and ultrathin 2D sheets of defect‐free graphene and metallic phase MoS2 are produced at high yields and high production rates by an ionic‐liquid‐assisted fluid dynamic exfoliation process. Hybrid 2D–2D layered films are fabricated by incorporating graphene sheets into compact metallic MoS2 films, thereby leading to ultrahigh volumetric capacitance, rate capability, and energy density in symmetric supercapacitor cells.