Fluorinated graphite nanosheets for ultrahigh-capacity lithium primary batteries

Traditional fluorinated carbon (CFx) batteries are greatly limited in their applications mostly because of inferior rate performances, initial voltage delay and low fluorine-to-carbon ratio below one. This work innovatively applies graphite nanosheets (NSs) as carbon source and optimizes the fluorination process at temperature range of 250–400 °C to prepare CFx NSs. Specifically, the edge defects and –CF2, –CF3 perfluorinated functional group active sites are introduced into NSs in the form of covalent/semi-covalent/semi-ionic bonds by adjusting the temperature which also breaks the limit of fluorocarbon ratio to achieve ultra-thin microstructure with high performances. In the battery assembly process, a series of discharge electrolytes are introduced to improve the quality and realize the ultrahigh specific capacity. The optimized CFx-400 °C NSs deliver an excellent specific capacity of 921 mAh·g−1 at a current density of 10 mA·g−1 with a high energy density value of 2210 Wh·kg−1. Moreover, the new electrolytes are selected which not only serve as electrolytes but also can be loaded on CFx surface for various discharge reactions without affecting the actual battery function. Thus, the lightweight tabs and current collectors are selected to control the loading of active material and injection coefficient. The presented battery design strategy provides a new strategy to achieve an ultrahigh specific energy density of 1116 Wh·kg−1.