Interlayer Engineering Construction of 2D Nb₂CT_x with Enlarged Interlayer Spacing Towards High Capacity and Rate Capability for Lithium‐Ion Storage

Abstract

The Li+ storage rate capability and diffusion dynamics in two‐dimensional (2D) materials are mainly determined by the interlayer spacing of materials. Investigating the effects of interlayer spacing on Li+ diffusion rate in 2D materials can provide a theoretical guidance for developing the high rate 2D materials for Li+ storage. Herein, a novel approach that P‐phenylenediamine (PPDA) electrostatically intercalated into Nb2CTx layers is employed to facilitate fast Li+ diffusion dynamics and improve diffusion rate for Li+ storage. The PPDA molecules existed between Nb2CTx layers have “support and dragline” effects on layers structure during Li+ insertion/exaction. The PPDA‐Nb2CTx not only enlarges interlayer spacing (d=1.27 nm) to accelerate the Li+ diffusion rate, but also enhances the layered structure stability due to the “support and dragline” effects of PPDA molecules. The PPDA‐Nb2CTx exhibits the excellent capacity of 400 mAh g−1 at a current density of 0.1 A g−1 and displays a superior capacity retention as 70.2 % at 5.0 A g−1 compared with that of 0.5 A g−1. The PPDA‐Nb2CTx//AC lithium ions hybrid capacitor (LIHC) delivers an excellent power density of 2754.8 W kg−1 at an energy density of 58.3 Wh kg−1 and a capacity retention with 80.0 % at 1.0 A g−1 after 1000 cycles. The interlayer engineering based on electrostatic intercalation provides a novel perspective to expand interlayer spacing, possessing a theoretical guidance for developing the Li+ storage materials with high‐rate capability.

Exploring 2D Energy Storage Materials: Advances in Structure, Synthesis, Optimization Strategies, and Applications for Monovalent and Multivalent Metal‐Ion Hybrid Capacitors

“…Organic molecules (such as maleic acid, [ 177 ] sodium tricyanomelaminate, [ 178 ] diamine [ 179 ] and p ‐phenylenediamine (PPDA) [ 180 ] )‐intercalated 2D materials were also reported with significantly improved performance. Zhang et al.…”

“…When a nonaqueous LIHC was assembled using Ti 2 CT x (LiF/HCl) negative electrode and LiNi 1/3 Co 1/3 Mn 1/3 O 2 positive electrode, an excellent energy density of 160 Wh kg −1 at 220 W kg −1 could be achieved. In addition, maleic acid (MA) chemical welded Ti 3 C 2 (MA‐Ti 3 C 2 ) [ 177 ] and PPDA‐propped Nb 2 CT x (PPDA‐Nb 2 CT x ) [ 180 ] were reported. The intercalation of different substances between the MXenes layers can not only expand the interlayer space, thereby exposing more active sites and improving ion diffusion kinetics, but also alleviate the self‐stacking which seriously affects the performance of the MXenes.…”

Diacid Molecules Welding Achieved Self-Adaption Layered Structure Ti3C2MXene toward Fast and Stable Lithium-Ion Storage

“…Therefore, the self-adaption layered structure MA-Ti 3 C 2 with enlarged interlayer spacing is designed to enhance the structure stability for improving the rate capability. In Figure d, the first CV cycles of MA-Ti 3 C 2 exhibit the irreversible peaks at 0.75 and 1.7 V, attributing to the SEI films and other side reaction between Ti 3 C 2 and surface functional groups . The sharp peaks located at 0.02 and 0.32 V corresponded to the lithiation and delithiation process, and the CV curves almost overlap with each other in the next cycles, indicating an excellent Li + storage performance.…”

“…In Figure 3d, the first CV cycles of MA-Ti 3 C 2 exhibit the irreversible peaks at 0.75 and 1.7 V, attributing to the SEI films and other side reaction between Ti 3 C 2 and surface functional groups. 58 The sharp peaks located at 0.02 and 0.32 V corresponded to the lithiation and delithiation process, and the CV curves almost overlap with each other in the next cycles, indicating an excellent Li + storage performance. In Figure 3e, MA-Ti 3 C 2 demonstrates a great discharge capacity of 498.9 mAh g −1 in the initial cycle and capacity hardly lost in the second and third cycles, suggesting an excellent cycling performance.…”

A Review on the Conventional Capacitors, Supercapacitors, and Emerging Hybrid Ion Capacitors: Past, Present, and Future

“…Liu et al reported the P ‐phenylenediamin was electrostatically intercalated into Nb 2 CT x layers (PPDA–Nb 2 CT x ), which not only endowed the increased interlayer distance to promote the Li + diffusion, but also improved layered structure stability attributed to the “support and dragline” effects. [ 116 ] The PPDA–Nb 2 CT x delivered an excellent capacity as 400 mAh g −1 under 0.1 A g −1 and the assembled PPDA–Nb 2 CT x //AC LIC exhibited an energy density up to 100.3 Wh kg −1 under 53.6 W kg −1 .…”