Ultrahigh-energy-density fluorinated calcinated macadamia nut shell cathodes for lithium/fluorinated carbon batteries

Lithium/fluorinated carbon (Li/CFx) batteries are widely applied in various industries because of the high energy densities of CFx compounds. However, incompatibility between high degrees of fluorination and the electrochemical activity of C-F bonds limits further improvements of the energy densities of CFx cathodes. Here, calcined macadamia nut shell is fluorinated with F-2 gas below 300 degrees C. The products deliver specific capacities exceeding 900 mAh g(-1), associated with discharge potentials exceeding 3.0 V (vs. Li/Li+). The product fluorinated at 280 degrees C achieves an unprecedented maximum energy density of 2585 W h kg(-1), surpassing the present maximum theoretical energy density of commercial (CF)(n) (2185 W h kg(-1)). Its electrochemical properties presumably originate from the complete destruction of the periodic crystalline lattice in the basal plane, which substantially alters the electron distribution within the C-F bonds. This study presents a new approach for designing exceptionally high-energy-density CFx compounds for lithium primary batteries using an accessible and inexpensive raw material. (C) 2019 Elsevier Ltd. All rights reserved.