Reticulate Dual‐Nanowire Aerogel for Multifunctional Applications: a High‐Performance Strain Sensor and a High Areal Capacity Rechargeable Anode

Abstract

Nanowire aerogels (NWAs) are highly versatile and used in many applications. However, most synthesized NWAs are composed of single components that may produce unsatisfactory aggregated performance in mechanical strength, conductivity, and electrochemistry. To address this issue, a reticulate dual-nanowire aerogel (rDNWA) composed of FeS 2 nanowires and carbon nanotubes (CNTs) via a simple solvothermal method is synthesized. The rDNWA possesses excellent compressibility (modulus of 1.32 MPa), good conductivity (0.65 S cm −1 ), and high porosity (>98%). It can be applied as a high-performance strain sensor with good sensitivity (Gauge Factor = 1.69) and enhanced stability. It can be densified to yield a high areal capacity of 10.0 mAh cm −2 and a high mass loading of 14.4 mg cm −2 after 100 cycles. As a freestanding anode for lithium ion battery (LIB), it exhibits a high specific mass capacity of 1031 mAh g −1 after 100 cycles at a current density of 100 mA g −1 and retains it to 729 mAh g −1 at a current density of 500 mA g −1 after 400 cycles. The outstanding overall performance of the hybrid aerogel is derived from the synergistic effect of intertwined CNTs and FeS 2 nanowires and can be extended to fabricate NWAs with novel multifunctional capabilities.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.201807467. management, sensing, catalysis, etc. [1][2][3][4][5][6][7] SNWAs have been constructed from metal (Cu, Ag, Pd) nanowires, [2,[8][9][10][11] metal oxide (TiO 2 , MnO 2 , K 2−x Mn 8 O 16 ) nanowires, [5,[12][13][14] and other inorganic nanowires (Silica, C, SiC) [4,[15][16][17] and they are all composed of single nanowires that often constrained them to a single outstanding performance in say either the mechanical strength, conductivity, or electrochemical property (capacity, stability, and rate performance for a lithium ion battery (LIB)) but unsatisfactory when their collective capabilities are considered. For example, the Cu NWAs reported by Jung et al. [9] have superior conductivity (116 S cm −1 ) but due to the weak Van der Waals forces its mechanical strength is relatively low (Young's modulus: 1.2 kPa). The MnO 2 NWA synthesized by Long et al. [14] is intrinsically nonconductive even though its 1230 mAh g −1 theoretical capacity for an LIB is high. Carbon nanotube (CNT) aerogels [4] possess a relatively low specific capacity (372 mAh g −1 ) for an LIB despite being highly compressible with an excellent mechanical strength. Typically, most SNWAs are unable to concurrently satisfy several material stipulations of strength, conductivity, active electrochemistry, strain sensing, etc., required in a multifunctional application.To address this issue, much effort has been focused on the fabrication of reticulate NWAs with multicomponents. The mechanical blending of nonconductive nanowires with conductive materials (graphene, for example) during a preparation process (via a sol-gel method) is an effective way to improve their conductivity. ...

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