High energy and high power primary Li-CFx_x batteries enabled by the combined effects of the binder and the electrolyte

Several effective methods have been developed recently to demonstrate simultaneous high energy and high power density in Li - carbon fluoride (CF$_x$) batteries. These methods can achieve as high as 1000 Wh/kg energy density at 60-70 kW/kg power density (40-50 C rate) in coin cells and 750 Wh/kg energy density at 12.5 kW/kg power density (20 C rate) in pouch cells. This performance is made possible by ingenious nano-architecture design, controlled porosity, boron doping and electrolyte additives. In the present study, we show that a similarly great performance, 931 Wh/kg energy density at 59 kW/kg power density, can be achieved by using a polyacrylonitrile binder and a LiBF4 electrolyte in Li - graphite fluoride coin cells. We also demonstrate that the observed effect is the result of the right combination of the binder and the electrolyte. We propose that the mechanistic origin of the observed phenomena is an electro-catalytic effect by the polyacrylonitrile binder. While our proposed method has a competitive performance, it also offers a simple implementation and a scalable production of high energy and high power primary Li-CF$_x$ cells.Comment: 13 pages, 8 figures, 1 tabl

Teflon: A Decisive Additive in Directly Fabricating Hierarchical Porous Carbon with Network Structure from Natural Leaf

Hierarchically porous carbons are of increasing importance due to their special physicochemical properties. The state-of-the-art approaches for synthesizing hierarchical porous carbon with network structure normally suffer from specific chemistries, rigid reaction conditions, high cost, and multiple tedious steps that limit their large scale production. Herein, we present an interesting insight into the important role of Teflon additive in fabrication of hierarchical porous carbon derived from biomass and, thus, use natural Indicalamus leaves for the first time to successfully synthesize hierarchical porous carbon with a three-dimensional morphology of interconnected nanoparticle units by using a facile and post-treatment-free carbonization technique. It is surprisingly found that the addition of Teflon not only reduces the synthesis procedure by combining post-removal of silica and carbonization in a single step but also plays a decisive role in generating the hierarchical carbonaceous network structure with a specific surface area as high as 1609 m²/g without any extra activation procedures. Benefiting from the combination of well-developed porosity and valuable hierarchical porous morphology, this type of hierarchical porous carbon has demonstrated attractive liquid-phase adsorption properties toward organic molecules