Molecular-Level Heterostructures Assembled from Titanium Carbide MXene and Ni–Co–Al Layered Double-Hydroxide Nanosheets for All-Solid-State Flexible Asymmetric High-Energy Supercapacitors

Abstract

Unique layered Ti3C2/Ni–Co–Al layered double hydroxide (LDH) heterostructures alternatively stacked with molecular-level nanosheets are for the first time synthesized by a facile liquid-phase cofeeding and electrostatic attraction heteroassemble strategy between negatively charged Ti3C2 and positively charged Ni–Co–Al-LDH nanosheets. The molecular-level Ti3C2/Ni–Co–Al-LDH heterostructures possessing the merits of both conductive and pseudocapacitive components can show greatly enhanced dynamic behavior in Faradaic reaction, which is significant for obtaining a high power density. Electrons penetrate in Ti3C2 layers, while ions diffuse rapidly along two-dimensional galleries, displaying the shortest diffusion pathway and highest efficiency for charge transfer. The Ti3C2/Ni–Co–Al-LDH heterostructure exhibits a specific capacitance of 748.2 F g–1 at current density of 1 A g–1, showing an enhanced rate capacity. Importantly, a maximum energy density of 45.8 Wh kg–1 is obtained when Ti3C2/Ni–Co–Al-LDH acts as the positive electrode for an all-solid-state flexible asymmetric supercapacitor. The results indicate that molecular-level heterotructure is a promising candidate for future high-energy supercapacitors.

Low‐Temperature Reduction Strategy Synthesized Si/Ti3C2 MXene Composite Anodes for High‐Performance Li‐Ion Batteries

“…To reveal the chemical bonding state between Si and MXene Ti 3 C 2 , an evolution of surface groups is investigated via FTIR spectra (Figure b). For both pure MXene Ti 3 C 2 and Ti 3 C 2 /Si samples, characteristic peaks around 3448 and 1630 cm −1 are observed, which are attributed to the stretching vibration of OH and CO bonds, respectively . The two bands at 1110 and 473 cm −1 are assignable to SiOSi asymmetric stretching and bending vibration.…”

“…In this regard, 2D Ti 3 C 2 MXene is an ideal alternative due to its high diffusion mobility of Li + ions (≈10 −10 –10 −9 cm 2 s −1 ) with lower Li + diffusion barrier (0.07 eV) than that of graphene (0.3 eV) . Ti 3 C 2 MXene also has been an attractive candidate for electrode materials of supercapacitors and anodes of LIBs due to the abundant surface redox reaction, which enables Ti 3 C 2 display significant contribution to the capacity rather than only work as conductive matrix. For instance, black phosphorus quantum dot (BPQD)/Ti 3 C 2 MXene nanosheet composites synthesized by an interfacial assembly strategy present a high reversible capacity of 1124 mAh g −1 at 50 mA g −1 when used as anodes of LIBs, which is attributed to the excellent conductivity of Ti 3 C 2 MXene and indispensable synergies of BPQD and Ti 3 C 2 MXene in capacity contribution .…”

Surface Modified MXene‐Based Nanocomposites for Electrochemical Energy Conversion and Storage

“…The authors have also demonstrated that these self‐assembled nanohybrids could be a versatile precursor toward MXene‐based alloy, metal sulfide, and trichalcogenidophosphate heterostructures. Then, the method was applied to the assembly of NiCoAl–LDH and Ti 3 C 2 T m MXene by Wang and co‐workers . The difference is, the electrostatic attraction was considered to be the driven force for the assembly of negatively charged Ti 3 C 2 T m and positively charged NiCoAl–LDH nanosheets.…”

Transition Metal Carbide Complex Architectures for Energy‐Related Applications

“…Another group of interesting self‐supported TMC film electrodes was Mxene‐based composites such as MXenes/RGO, MXenes/CNTs, MXenes/C 3 N 4 , MXenes/metals oxides, and MXenes/LDH . For examples, the Feng group has designed a flexible all‐solid‐state supercapacitor with Ti 3 C 2 T x MXene‐graphene composites as the electrode .…”

“…The Qiao group used the Ti 3 C 2 MXenes and g‐C 3 N 4 to design free‐standing flexible MXenes/C 3 N 4 films for high‐performance OER and Zn‐air batteries (Figure c) . The Ti 3 C 2 T x MXenes coupled with the metal oxides and LDH nanosheets to form the self‐supported film electrodes for LIBs, and all‐solid‐state flexible SCs were also realized . Another type of self‐supported TMC film electrode of Mo 2 C/N‐rGO film was assembled by the filtration of the MoO 3 and GO, and this film electrode showed highly efficient HER activity …”