Research progress in fluorinated carbon sources and the discharge mechanism for Li/CF_xprimary batteries

Abstract

Lithium/fluorinated carbon (Li/CFx) primary batteries are still receiving extensive attention in particularly the study of CFx cathodes has made great progress in recent years with the discovery of new carbon sources.

Boosting the Electrochemical Performance of Primary and Secondary Lithium Batteries with Mn-Doped All-Fluoride Cathodes

“…The higher the fluorination temperature, the greater the degree of fluorination (x), and the worse the conductivity of CF x . 32 To improve the dynamic properties of the composites, the strategy of Mndoping was adopted in the synthesis of FeF 3 . The optimal gas phase fluorination temperature was determined to be 350 °C, at which not only Fe and Mn in the Mn-doped Fe 3 C@C can be converted into FeF 3 and MnF 3 but also most of the carbon in FeF 3 @C can be converted into CF x at the same time, to produce Mn y Fe 1−y F 3 @CF x composites (FM7).…”

“…When the fluorination temperature is further increased, a large number of FeF 3 -coated carbon materials can be converted into CF x with electrochemical activity and form perfluorinated FeF 3 @CF x composites, which improves the specific capacity of the composites. The higher the fluorination temperature, the greater the degree of fluorination ( x ), and the worse the conductivity of CF x . To improve the dynamic properties of the composites, the strategy of Mn-doping was adopted in the synthesis of FeF 3 .…”

“…Therefore, a reaction temperature lower than 600 °C is commonly used, and the higher the fluorination degree, the worse the conductivity of CF x . 32 To obtain higher energy density, it is necessary to increase significantly the load mass of the active substances and to reduce the proportion of the inactive substances. 33 In this study, most of the substances in the cathode were converted into electroactive fluoride by NF 3 gas phase fluorination to gain perfluorinated compounds, i.e., the carbon in the FeF 3 /C composite was converted into CF x with electrochemical activity, to improve the energy density of the electrode.…”

“…The higher the fluorination reaction temperature, the higher the fluorine content (0.5 < x < 1) and the higher the specific capacity of the material, but an excessively high temperature may lead to the decomposition of carbon fluoride. Therefore, a reaction temperature lower than 600 °C is commonly used, and the higher the fluorination degree, the worse the conductivity of CF x …”

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

“…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 ].…”