MXenes@Te as a composite material for high-performance aluminum batteries

Abstract

The emerging two-dimensional (2D) materials, MXenes, play an important role in various fields of energy storage and exhibit excellent electrochemical performance. Herein, we prepared few-layered MXenes (F-Ti 3 C 2 T x ) and loaded Te on the surface of F-Ti 3 C 2 T x by using a simple hightemperature evaporation method. In addition, the electrochemical performance of the aluminum battery with F-Ti 3 C 2 T x as support material was studied. The initial charge/discharge specific capacities are 987/1096 mA h g −1 at 0.2 A g −1 . An obvious discharge voltage plateau of about 1.3 V appears at various current densities. The specific capacity is about 258 mA h g −1 with MXenes@Te as the active material in the aluminum battery, which benefits from the excellent electronic conductivity of the MXenes and their 2D layered structure. Density functional theory calculations were carried out to explore the mechanism. Ti 3 C 2 O 2 @Te is more inclined to adsorb [AlCl 4 ] − than Ti 3 C 2 O 2 . Furthermore, the valence change behavior of element Te was studied by using thermodynamic calculation (FactSage 7.1). X-ray photoelectron spectroscopy results show that when the battery is fully charged to 2.4 V element Te and Ti ions (Ti 3+ , Ti 2+ ) are oxidized to Te 4+ and Ti 4+ . In contrast to the charging process, the high-valence Te 4+ and Ti 4+ are reduced again during discharging. Element Te is reduced to lower-valence Te 2− when the discharge voltage is lower than 0.6 V, and a higher charge voltage (2.56 V) is required for Te to be oxidized to Te 6+ .

In Situ Selenization of Ti3C2Tx Assisted by Cu2+ with Superior Performance for Aluminum Ion Batteries

“…According to Bragg’s law, where d is the spacing of the crystal, θ is half of the diffraction angle, λ is the wavelength, and n is the reflection level; the smaller the value of θ, the larger the interlayer distance along the c -axis. Therefore, the adsorption of Cu 2+ benefits to the expansion of the layer structure, which will contribute to ion diffusion during the electrochemical progress . Raman tests were carried out on the material and the tests revealed the presence of TiSe 2 , which was added to the support as shown in the figure below.…”

High Performance and Long‐cycle Life Rechargeable Aluminum Ion Battery: Recent Progress, Perspectives and Challenges

“…In terms of capacity, rate capability, and structural stability, hybrid MXenes, which include both early and late transition metals, can provide a more balanced performance. [135][136][137] MXene and N-doped carbon (NC) shells have been composited with Ni 0.6 Co 0.4 S (Ni 0.6 Co 0.4 S@MXene@NC) for AIBs in the literature. Ni 0.6 Co 0.4 S can reversibly store Al ions with improved Al 3 + intercalation/deintercalation kinetics in the designed hybrid, whereas MXene and NC can not only facilitate electron transfer, but also contribute to high chemical and structural stability by inhibiting active species dissolution and allowing for favorable volume change tolerance (Figure 10).…”

“…After 150 cycles with a current density of 0.6 A g À 1 , the specific capacity was 449 mAh g À 1 , and the capacity retention rate was at 70 %. [135]…”

“…A major reaction mechanism in rechargeable batteries is the intercalation (deintercalation) of carrier ions into (from) the interlayer region of stacked MXenes. In terms of capacity, rate capability, and structural stability, hybrid MXenes, which include both early and late transition metals, can provide a more balanced performance [135–137] . MXene and N‐doped carbon (NC) shells have been composited with Ni 0.6 Co 0.4 S (Ni 0.6 Co 0.4 S@MXene@NC) for AIBs in the literature.…”

“…To overcome such problems, few‐layered MXenes (F‐Ti 3 C 2 Tx) were synthesized, then Te was loaded onto the surface of F‐Ti 3 C 2 Tx using a simple high‐temperature evaporation process. After 150 cycles with a current density of 0.6 A g −1 , the specific capacity was 449 mAh g −1 , and the capacity retention rate was at 70 % [135] …”