Fig. 1
From: In situ X-ray diffraction studies on nominal composition of C2Li under high pressure and temperature
Characteristics and preparation of \(\hbox {C}_{2}\)Li. (a, b) Schematic crystal structures of \(\hbox {C}_{6}\)Li and \(\hbox {C}_{2}\)Li along the \(c_\textrm{h}\)-axis (left) and in the graphite layer (right). \(I_\textrm{c}\) is the repeated distance between the Li\(^{+}\) ions layers along the \(c_\textrm{h}\)-axis. The \(a_\textrm{h}\) values of C\(_{6}\)Li and \(\hbox {C}_{2}\)Li are approximately 4.30 and 2.49 Å, respectively. (c) Simulated XRD patterns for \(\hbox {C}_{6}\) (\(P6_{3}/mmc\)), \(\hbox {C}_{6}\)Li (P6/mmm), and \(\hbox {C}_{2}\)Li (P6/mmm) with respect to the d value. (d) Schematic of the procedure for synthesizing \(\hbox {C}_{2}\)Li in this study. Two samples of \(\hbox {C}_{2}\)Li were initially prepared in the nominal composition through two different methods, and the resulting samples are referred to as \(\hbox {C}_{6}+3\)Li and \(\hbox {C}_{6}\)Li + 2Li. Then, each sample was installed in a HP capsule (Ta), pressurized at 10 GPa, and heated at 400 \(^{\circ }\hbox {C}\) for 30 min. Energy-dispersive XRD measurements were conducted during the HP-HT synthesis. (e) Discharge curve of the C\(_{6}\)/Li cell for preparing \(\hbox {C}_{6}\)Li\(_{x}\) with x = 0.98. Inset: \(\hbox {C}_{6}\)Li\(_{0.98}\) pellet just after the discharge reaction.
