Diamine molecules double lock-link structured graphene oxide sheets for high-performance sodium ions storage

ACS Appl. Mater. Interfaces

Huang

Cai

et al. 2021

Boosting sufficient Li + ion mobility in Li 4 Ti 5 O 12 (LTO) is crucial for high-rate performance lithium storage. Here, an ultrafast charge storage oxygen vacancy two-dimensional (2D) LTO nanosheet was successfully fabricated through a one-pot hydrothermal method. The selectively doped Al 3+ into octahedron Li + /Ti 4+ 16d sites not only provide bulk oxygen vacancy and appropriate distorted TiO 6 octahedra to facilitate Li + ions diffusion, but also serve as a "pillar" to stabilize the Ti−O framework. The oxygen vacancy lowers Li + ion diffusion energy barrier. Moreover, the 2D structure provides open diffusion channels for fast Li + ion transport. As a result, the sample shows excellent electrochemical performance for bifunctional lithium storage. As a lithium-ion battery anode, the capacity retention reaches 112.8 mA h g −1 after 5000 cycles at 40 C with a fading rate of 0.288% per 100 cycles. Meanwhile, as a lithium-ion capacitor anode, it exhibits an excellent rate capacity of 120 mA h g −1 after 5000 cycles at 500 C with nearly 100% Coulombic efficiency. The produced LTO shows much higher rate capacity and longer lifetime than the reported LTO. Density functional theory calculations also demonstrate that oxygen vacancy can facilitate Li + ion diffusion kinetics. The relationship between oxygen vacancy content and Li + ions diffusion energy barrier in LTO is quantified. This work pioneers a defect engineering strategy for synthesized high-performance electrode materials.

Section: Introductionmentioning

confidence: 99%

Oxygen Vacancy Enhanced Two-Dimensional Lithium Titanate for Ultrafast and Long-Life Bifunctional Lithium Storage

ACS Appl. Mater. Interfaces

Huang

Cai

et al. 2021

“…Fourier transform infrared (FTIR) spectra are exhibited in Figure b; the strong absorption peaks at 1441 and 3293 cm –1 corresponding to C–N and N–H bonds of Ti 3 C 2 -NH 2 and CC bonds at 1183 cm –1 are attributed to MA molecules. It is worth noting that the adsorption peak at 1625 cm –1 is CO in HN–CO bonds, , which further proves that MA molecules are linked with Ti 3 C 2 layers to form MA-Ti 3 C 2 . The X-ray photoelectron spectra (XPS) of MA-Ti 3 C 2 displays a new N 1s peak compared with pure Ti 3 C 2 , suggesting that N elements are introduced by chemical welding Ti 3 C 2 and MA molecules (Figure S1).…”

Section: Resultsmentioning

confidence: 99%

“…According to eq , the Li + diffusion coefficient ( D Li+ ) is inversely proportional to σ, in which the σ values of MA-Ti 3 C 2 and Ti 3 C 2 are 518.7 and 689.9, respectively (Figure b), illustrating that the approach of regulating interlayer spacing is significant to fast Li + diffusion. As shown in Figure c, the GITT test process can be divided into three stages: pulse, constant current, and relaxation, in which the diffusion coefficient ( D Li+ ) can be deduced directly from the following equation where L is the thickness of electrode sheets, τ is the relaxation time, and Δ E s and Δ E τ represent the total change of the voltage during current pulse and the change in steady-state voltage during the step at the plateau potentials, respectively. Specifically, the D Li+ values of MA-Ti 3 C 2 and Ti 3 C 2 are 1.4 × 10 –8 –5.8 × 10 –7 and 2.1 × 10 –9 –2.2 × 10 –7 cm 2 s –1 (Figure d), respectively, declaring that MA-Ti 3 C 2 with self-adaption layered structure can offer fast Li + transport pathways for facilitating Li + diffusion dynamics.…”

Section: Resultsmentioning

confidence: 99%

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

ACS Sustainable Chem. Eng.

Zhang

et al. 2021

Self Cite

Ti 3 C 2 has been considered as a potential material for lithium-ion storage because of its abundant surface terminals, excellent metal-like conductivity, and modifiable layered structure. However, the Li + diffusion rate in interlayer is limited by the small interlayer spacing determined by the van der Waals forces. Herein, the dehydration condensation reaction between amino-functionalized Ti 3 C 2 (Ti 3 C 2 -NH 2 ) and maleic acid (MA) molecules was utilized to enlarge the interlayer spacing of Ti 3 C 2 . The MA molecules were successfully welded into interlayers of Ti 3 C 2 by HN−CO bonds (namely, chemical welding) and MA chemical welded Ti 3 C 2 (MA-Ti 3 C 2 ) with self-adaption layered structure were obtained. The MA molecules can contribute double effects to the layered structure of Ti 3 C 2 , and they act as chains to remit the volume change during Li + insertion and serve as pillars to enhance the structure stability during Li + extraction. The MA-Ti 3 C 2 exhibits an interlayer spacing of 1.28 nm, a fast Li + diffusion rate (1.4 × 10 −8 to 5.8 × 10 −7 cm 2 s −1 ), and improved Li + storage performance. The MA-Ti 3 C 2 //AC lithium-ion capacitor (LIC) demonstrates an excellent energy density of 102.5 Wh kg −1 at 200 W kg −1 and cycle stability with 76.3% at 1.0 A g −1 after 1000 cycles. This novel chemical welding delivers an effective perspective for modifying the layered structure, enhancing the structure stability, and achieving fast Li + diffusion and high-rate capability of twodimension materials.

“…In addition, the Li + diffusion resistance of PPDA‐Nb 2 CT x and Nb 2 CT x can be quantificationally evaluated by Li + diffusion coefficients, which is achieved from GITT measurements (Figure 5e and S5). According to Equation S4, the Li + diffusion coefficients of PPDA‐Nb 2 CT x and Nb 2 CT x at different potentials can be obtained (the positive sign only represents charge process and negative sign represents discharge process) [44] . In Figure 5f, the Li + diffusion coefficient (1.5×10 −9 ∼4.6×10 −7 cm 2 s −1 ) of PPDA‐Nb 2 CT x is higher than that of Nb 2 CT x (1.2×10 −9 ∼2.6×10 −7 cm 2 s −1 ), indicating the intercalation of PPDA molecules can not only offer a large specific surface area to improve Li + storage performance, but also expand interlayer spacing to accelerate Li + diffusion rate.…”

Section: Resultsmentioning

confidence: 99%

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

Zhang

et al. 2021

Batteries & Supercaps

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.