Densifiable Ink Extrusion for Roll-to-Roll Fiber Lithium-Ion Batteries with Ultra-High Linear and Volumetric Energy Densities.

Conventional bulky and rigid planar architecting power systems are difficult to satisfy the growing demand for wearable applications. One-dimensional fiber batteries bearing appealing features of miniaturization, adaptability, and weavability, represent a promising solution, yet challenges remain pertaining to energy density and scalability. Herein, an ingenious densifiable functional ink is invented to fabricate scalable, flexible, and high mass loading fiber lithium-ion batteries (LIBs) by adopting a fast ink-extrusion technology. In the formulated ink, pyrrole-modified reduced graphene oxide (py-rGO) is elaborately introduced and exerts multiple influences: not only assembles carbon nanotubes (CNTs) and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) to compose a sturdy, conductive and agglomeration-free three-dimensional network that realizes an ultra-high content (75 wt%) of the active materials and endows the electrode excellent flexibility, but serves as a capillary densification inducer, encouraging an extremely large linear mass loading (1.01 mg cm -1 per fiber) and packing density (782.1 mg cm -3 ). As a result, the assembled fiber LIBs deliver an impressive linear and volumetric energy densities with superb mechanical compliance, demonstrating the best performance among all the reported extruded fiber batteries. This work highlights a highly effective and facile approach to fabricate high-performance fiber energy storage devices for future practical wearable applications. This article is protected by copyright. All rights reserved.