Multifunctional Nanocomposites with High Strength and Capacitance Using 2D MXene and 1D Nanocellulose

Abstract

Structural electrode materials that integrate high mechanical strength and high electrochemical performances are attractive as they are indispensable for building lightweight, flexible electronics. [1][2][3] These materials should be able to withstand extreme mechanical stress and deformations while maintaining high charge storage properties, and thereby decrease the electrochemically inactive weight and volume for packaging of devices, especially in limited spaces. [1] Most conventional electrode materials, however, fail to meet both requirements. [4] Some of reported strategies involved using carbon fiber-reinforced composites [5,6] or graphene-based materials [1] as structural electrodes to deliver mechanical strength. These materials, however, fall short on the electrochemi cal energy storage capacitance. Alternatively, metal oxides [7] or conducting polymers [8] can be incorporated to boost the capacitance of the graphene-based materials. The problem is the weak interactions between different components, which results in low mecha nical stability of the final composites. [7,9] Therefore, there is a crucial need for the development of new-generation structural energy storage nanocomposites, which monolithically integrate excellent mechanical properties, high electronic and ionic conductivities, and high charge storage capabilities. A balance should also exist between these properties without substantially sacrificing one property over the other. [1] The family of two-dimensional (2D) metal carbides and nitrides, collectively known as MXene, are interesting materials for building high-performance supercapacitors. [10][11][12][13][14][15][16] MXenes have a general formula of M n+1 X n T x , where M is an early transition metal such as Ti, X is carbon or nitrogen, and T x indicates the presence of different functional groups (O, OH, and F) on the surface of metal layers, a result of aqueous exfoliation synthesis of MXenes. [10,17,18] Ti 3 C 2 T x MXene has been widely reported as a high-performance electrode material either in its pristine form or in hybrids with other guest materials such as poly(vinyl alcohol) (PVA), [18] polypyrrole, [19,20] and polyaniline, [21] as well as in hybridization with other carbon materials such as graphene, [22] carbon nanotubes, [23][24][25] and carbon nanofibers. [26] Most of the MXene hybrid nanocomposites, however, have only shown improvement in either capacitance or mechanical properties while sacrificing one property over the other, and they lack the required mechanical integrityThe family of two-dimensional (2D) metal carbides and nitrides, known as MXenes, are among the most promising electrode materials for supercapacitors thanks to their high metal-like electrical conductivity and surface-functional-group-enabled pseudocapacitance. A major drawback of these materials is, however, the low mechanical strength, which prevents their applications in lightweight, flexible electronics. A strategy of assembling freestanding and mechanically robust MXene (Ti 3 C 2 T x ) nanoco...

A Facile, High‐Yield, and Freeze‐and‐Thaw‐Assisted Approach to Fabricate MXene with Plentiful Wrinkles and Its Application in On‐Chip Micro‐Supercapacitors

“…The energy density of m‐MSC is in the range of 10.3 to 29.6 mWh cm −3 with a corresponding power density in the range of 18.6 to 3.1 W cm −3 . Remarkably, these values are higher than lithium thin‐film batteries (<10 mWh cm −3 ), commercial super‐capacitors (5.5 V/100 mF), and reported MXene‐related MSCs like all‐MXene MSCs (18 mWh cm −3 ), MXene film MSCs (12.4 mWh cm −3 ), MXene/graphene (1.4 mWh cm −3 ), MXene/cellulose nanofiber (0.9 mWh cm −3 ), etc.…”

“…In addition, FAT‐MXene MSC keeps about 97.8% of capacitance retention after 2000 cycles of charge and discharge (Figure S14, Supporting Information). Figure i shows the Ragone plots to compare the volumetric energy and power density of FAT‐MXene MSC with those of other graphene‐or MXene‐related MSCs and commercially available energy storage devices . The details of these MSCs are listed in Table S1, Supporting Information.…”

Pristine Titanium Carbide MXene Films with Environmentally Stable Conductivity and Superior Mechanical Strength

“…Generally, H 2 O molecules existed in Ti 3 C 2 T x films as bound water (mainly intercalated monolayer type water) could influence the conductivity and mechanical properties from the previous reports, henceforth the control of this type of H 2 O (typically by vacuum annealing at 150 °C) is not the main point in this work. What we expected to explore is the impact of confined water in Ti 3 C 2 T x films on mechanical properties, and the water content was controlled by stabilizing the film samples at 60 °C/10% RH and 20 °C/75% RH for 48 h. Interestingly, in 75% RH environment, stress–strain curves of pristine Ti 3 C 2 T x films were characterized by a hardening region at larger strain, which therefore rendered the record‐high strain energy of 1.48 ± 0.19 MJ m −3 and ultimate strength up to 114 MPa (of 0.1 m H + induced films) in pure Ti 3 C 2 T x films (Figure d; Table S1, Supporting Information) . The larger failure strain and lower modulus of films in 75% RH environment are the results of plasticity effect of H 2 O whereas the higher strength at large strain featured in pristine Ti 3 C 2 T x films implies the enhanced layer interactions (Figure S13, Supporting Information).…”

High‐Strength and Tough Crystalline Polysaccharide‐Based Materials†

“…producing resultant nanocomposites with tensile strengths as high as 416 MPa while maintaining high electrical conductivities of up to of 690 S/cm. [ 20 ]…”

“…There are two typical material‐processing strategies: “top‐down” and “bottom‐up”. Both approaches have been widely applied for constructing polysaccharide‐based materials including hydrogels, [ 15,16 ] aerogels/carbon aerogels, [ 17,18 ] microspheres, [ 19 ] nanocomposites, [ 20 ] sponges, [ 21 ] bioplastics, [ 22 ] and membranes. [ 23 ] Crystalline polysaccharide‐based materials have been successfully utilized in various applications like textiles, [ 24 ] building blocks, [ 25,26 ] sensors, [ 27 ] water treatment, [ 28 ] heat‐insulators, [ 29 ] ionic conductors, [ 30 ] battery separators, [ 31 ] energy storage materials, [ 32 ] solar steam generators, [ 33 ] and biomedical devices.…”