Dual Active and Kinetically Inter-Promoting Li3VO4/Graphene Anode Enabling Printable High Energy Density Lithium Ion Micro Capacitors

Planar micro-supercapacitors (MSCs) with high energy/power densities and long cycle life are expected to expedite the development of the future wearable miniaturized electronics. However, its low energy density issue always falls short in ever-increasing demands of specific energy consumption. Herein, a dual active and kinetically inter-promoting Li3VO4 (LVO)/graphene composite is designed as the anode for high energy density lithium ion micro capacitors (LIMCs). The LVO nanoparticles are evenly confined on graphene nanosheets through an atomic layer pre-deposition (ALD) technique, which substantially disperses the nucleation site and impedes the coarse grain growth in the successive solid-state formation of LVO. The much-promoted reaction kinetics of LVO and graphene substrate with sufficient diffusion space in the interdigital electrodes of LIMCs synergistically boost the three-dimensional and efficiently lithium ion storage behavior. The LVO/graphene exhibits extraordinary rate capability (98.5 mAh g−1 at 40 A g−1 (100 C)) and long-term stability. All the current collectors and asymmetric interdigital electrodes are spray printed, opening a facile and delicate technique for a large-scale production of LIMCs. The LIMCs deliver a superior volumetric energy density of 51.4 mWh cm−3, excellent flexible and cyclic stability, demonstrating a great potential for the future miniaturized, flexible, and high-performance energy storage devices.