FeCl₃ Intercalated Microcrystalline Graphite Enables High Volumetric Capacity and Good Cycle Stability for Lithium‐Ion Batteries

Abstract

To achieve a high volumetric capacity, both high tap density and high gravimetric capacity should be considered in one electrode. Herein, microcrystalline graphite (MG), a type of excellent graphite host, is proposed for the large‐scale preparation of FeCl3‐intercalated graphite intercalation compounds (GICs) to simultaneously meet the requirements of high tap density (0.95 g cm−3) and high gravimetric capacity (905 mAh g−1). FeCl3‐intercalated MG achieves the integration of isotropic orientation structure, amorphous carbon ingredients between graphite grains, and crumpled graphite layers, thus effectively buffering structure expansion and suppressing the dissolution of soluble FeCl3 guest and LiCl discharge products. In a lithium‐ion cell, the anode shows a high volumetric capacity of 859 mAh cm−3 and a stable cycle performance for lithium‐ion storage. More importantly, the influence of microstructure features of GICs on their electrochemical properties is demonstrated, which may be of great value to better design and prepare other GIC anodes for high volumetric capacity and good cycle stability.

AlCl3-graphite intercalation compounds as negative electrode materials for lithium-ion capacitors

“…As previously reported, the graphitization degree affects the MCl x -GIC structure. 27 The increased interlayer spacing due to AlCl 3 intercalation was reported in the literature to be 0.954 nm. 26 When comparing the GIC (00l) and graphite (002) plane intensity ratios, the ratios of the AlCl 3 -GICs (200 and 150) were higher than those of the AlCl 3 -GICs (135 and 115).…”

“…In previous reports, the wavenumber of the G bands of metal chloride-GICs such as FeCl 3 -GICs shied to higher values due to electron donation from the graphite host to the guest metal chlorides. 21,22 In this study, the same observation was made for each of the AlCl 3 -GICs. Therefore, the intercalation of AlCl 3 is believed to have occurred in all the products.…”

“…It has been reported that FeCl 3 conversion occurs at 0.2 V. In addition, the peaks may also be due to Li + absorption in the pores as observed in hard carbon and surface capacitance. 13,21,22,34 Fig. S5 † and 6b show the charge/discharge curves of the initial and second cycle at 0.1 A g À1 , respectively.…”

“…However, graphite negative electrodes suffer from limited rate capability, owing to the sluggish solid phase diffusion of Li + ions, and a low Li + ion capacity. 7,9 Metal-chloride graphite intercalation compounds (MCl x -GICs) such as FeCl 3 -GICs, which have been reported as LIB negative electrodes, [21][22][23] are attractive alternatives to graphite. FeCl 3 -GICs have a structure consisting of graphite as the host material and FeCl 3 as the guest material.…”

Macroscopic yarns of FeCl3-intercalated collapsed carbon nanotubes with high doping and stability

“…In the intercalated state, single-wall carbon nanotubes (SWCNTs) have shown new optical absorption bands with Br2, Cs and AuCl3 at saturation doping [13,14], a decrease in work function, e.g., with AuCl3 [14], and simultaneous increase in electrical conductivity and mechanical properties in I2 intercalated CNT fibres [7]. GICs additionally show superconductivity, e.g., in KC8 and CaC6 compounds [15], increased energy storage capacities by using FeCl3-intercalated graphites as anode [16][17][18], among other properties. Indeed, producing continuous, macroscopic fibres of intercalated CNTs with the rich properties of GICs has been an attractive prospect since the early days of CNT research [19].…”