High-Energy and High-Power Primary Li-CFx Batteries Enabled by the Combined Effects of the Binder and the Electrolyte

Abstract

Several effective methods have been developed recently to demonstrate simultaneous high energy and high power density in Lithium - carbon fluoride (Li-CFx) batteries. These methods can achieve as high as a 1000 Wh/kg energy density at a 60–70 kW/kg power density (40–50 C rate) in coin cells and a 750 Wh/kg energy density at a 12.5 kW/kg power density (20 C rate) in pouch cells. This performance is made possible by an ingenious nano-architecture design, controlled porosity, boron doping, and electrolyte additives. In the present study, we show that a similarly great performance, a 931 Wh/kg energy density at a 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 of 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-CFx cells.

High Energy Density of Ball-Milled Fluorinated Carbon Nanofibers as Cathode in Primary Lithium Batteries

“…This method could be used for a variety of materials [ 8 , 15 ]. Some improvements in the electrolyte composition (e.g., [ 23 , 25 ]) could also be used for milled fluorinated nanofibers.…”

“…Because fluorinated carbons (CFxs) exhibit the highest theoretical energy density among current cathode materials for lithium primary batteries, extensive efforts are devoted to the enhancement of either their energy density, their power density, or both (see recent review papers [ 1 , 2 , 3 , 4 ]). The very recent strategies involve (i) considering new carbonaceous precursors for fluorination or innovative fluorination routes [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ], (ii) chemical changes in the CFx, either on the surface or in the bulk [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ], and (iii) change in the electrolyte composition [ 13 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ]. Ball milling, a simple process for reducing the particle size of a compound, is widely used for electrode materials [ 30 , 31 , 32 , 33 , 34 ], creating more space to accumulate the LiF(s) particles formed.…”