Interface‐Structure‐Modulated CuF₂/CF_x Composites for High‐Performance Lithium Primary Batteries

Abstract

Lithium primary batteries are widely used in various fields where high energy densities and long storage times are in demand. However, studies on lithium primary batteries are currently focused on the gravimetric energy densities of active materials and rarely account for the volumetric energy requirements of unmanned devices. Herein, CuF2/CFx composites are prepared via planetary ball milling (PBM) to improve the volumetric energy densities of lithium primary batteries using the high mass density of CuF2, achieving a maximum volumetric energy density of 4163.40 Wh L−1. The CuF2/CFx hybrid cathodes exhibit three distinct discharge plateaus rather than simple combinations of the discharge curves of their components. This phenomenon is caused by charge redistribution and lattice modulation on the contact surfaces of CuF2 and CFx during PBM, which change the valence state of Cu and modify the electronic structures of the composites. As a result, CuF2/CFx hybrid cathodes exhibit unique discharge behaviors and improved rate capabilities, delivering a maximum power density of 11.16 kW kg−1 (25.56 kW L−1). Therefore, it is a promising strategy to further improve the comprehensive performance of lithium primary batteries through the use of interfacial optimization among different fluoride cathodes.

The Fluorination of Boron‐Doped Graphene for CFx Cathode with Ultrahigh Energy Density

“…[4][5][6] However, the insulated nature of CF x due to the sp 3 hybridization of covalent C-F bond, especially for CF x compounds with high fluorination degree, hinders the performance of Li/CF x battery, including low rate capability, large polarization upon discharge, and severe heat generation during operation. [7][8][9] Therefore, various attempts have been made in the past years to improve the electrochemical performances of CF x discharged at high current densities. These include the formation of a semi-ionic C-F bond, [10][11][12][13] the design of nanostructured CF x , [14][15][16][17] and conductive surface coating.…”

Surface Engineering of Fluorinated Graphene Nanosheets Enables Ultrafast Lithium/Sodium/Potassium Primary Batteries

“…Importantly, the DFG-N prepared in this work exhibits an unprecedented power density based on its ultrafast discharge capability and high discharge voltage compared to the previously reported power density of CF x cathodes (Figure 4h; Table S3, Supporting Information). [12,16,17,20,28,30,31,36,[41][42][43][44][45][46][47][48][49][50] Electrochemical impedance spectroscopy (EIS) was first used to investigate the underlying causes for electrochemical performance differences between pristine FG, surface-engineered DFG-x and DFG-N. As shown in Figure 5a, the EIS spectra were measured after discharging at 1 C to a 10% depth of discharge (DOD) state. The symbols R b , R ct , CPE1, and Z w , depicted in the set of Figure 5b, represent bulk ohmic resistance, charge-transfer resistance, double-layer capacitance, and Warburg impedance, respectively.…”

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

“…In addition to the fluorination temperature, the addition of composites can also affect the C–F bonding, and Sun et al 94 showed that the perfluorinated-CF 2 /CF 3 in the F 1s spectrum decreased with increasing CuF 2 content in XPS tests, while the proportion of half-ion (C x F) n increased instead. As shown in Fig.…”