Employing renewable, earth-abundant, environmentally friendly, low-cost natural materials to design flexible supercapacitors (FSCs) as energy storage devices in wearable/portable electronics represents the global perspective to build sustainable and green society. Chemically stable and flexible cellulose and electroactive lignin have been employed to construct a biomass-based FSC for the first time. The FSC was assembled using lignosulfonate/single-walled carbon nanotube (Lig/SWCNT) pressure-sensitive hydrogels as electrodes and cellulose hydrogels as an electrolyte separator. The assembled biomass-based FSC shows high specific capacitance (292 F g at a current density of 0.5 A g), excellent rate capability, and an outstanding energy density of 17.1 W h kg at a power density of 324 W kg. Remarkably, the FSC presents outstanding electrochemical stability even suffering 1000 bending cycles. Such excellent flexibility, stability, and electrochemical performance enable the designed biomass-based FSCs as prominent candidates in applications of wearable electronic devices.

Wearable supercapacitors, as one of the most important power supplies for wearable electronics, require excellent flexibility and deformability and a structure that is not easily delaminated. In this work, a robust ligninsulfonate/single-wall carbon nanotube film/holey reduced graphene oxide (Lig/SWCNT/HrGO) film with excellent tensile strength (121.8 MPa) and flexibility has been prepared via a filtration process followed by a hydrothermal treatment. During the filtration process, the SWCNT and small-size holey graphene oxide (HGO) can form a multilayer-like interconnected structure, and a part of HGO with a large specific surface area intersperses in the SWCNT network. HGO can be further reduced to HrGO, and the HrGO, Lig, and SWCNT can combine tightly to generate a compact multilayer-like structure during the hydrothermal process. High-strength, flexible, porous cellulose hydrogel (9.56 MPa) has been fabricated via a self-enhancing method through phase inversion of microcrystalline cellulose and partially dissolved bacterial cellulose mixture dispersion. A wearable supercapacitor is assembled by the Lig/SWCNT/HrGO films and self-enhancing cellulose hydrogel, which exhibits excellent tensile strength (112.3 MPa), areal capacitance (1121 mF cm–2), and energy density (77.8 μWh cm–2). More importantly, the areal capacitance shows a nearly linear increase with an increase in the mass of the film electrode. When the film electrode mass reaches up to 16.5 mg cm–2, the wearable supercapacitor delivers an ultrahigh areal capacitance of 4110 mF cm–2 and an energy density of 285.4 μWh cm–2. Remarkably, the wearable supercapacitor can sustain many types of arbitrary deformation and this outstanding flexibility is attributed to the strong interaction between wood-derived cellulose and Lig, which prevents the delamination of the electrodes and the separator. This work provides a facile approach for the preparation of a biopolymer-based, multilayer-like structure film and a self-enhancing method to obtain high-strength cellulose hydrogel, thus developing a biomimetic high-performance wearable energy storage device.

The preparation of graphene-based aerogels with excellent mechanical strength, elasticity, and compressibility is still a challenge. Herein, we demonstrate a robust, elastic, and lightweight graphene/aramid nanofiber/polyaniline nanotube (rGO/ANF/PANIT) aerogel that is prepared by mixing graphene oxide (GO), ANF, and PANIT dispersions, followed by thermal treatment at 90 °C, freeze-drying, and a low-temperature annealing process. The PANIT bonds the graphene sheets tightly, benefitting the formation of composite gels. The ANF tightly interconnects the graphene sheets and further reinforces the composite network framework significantly, hence endowing rGO/ANF/PANIT composite aerogels with robust mechanical property. The prepared aerogels present a low density of ∼12 mg cm −3 , high conductivity, good resilience, and high compressibility. The rGO/ANF/PANIT aerogels as pressure sensors exhibit a high sensitivity of 1.73 kPa −1 , low detection limit (40 Pa), wide detection range, and excellent compressive cycle stability, highlighting the promising applications in pressure-sensitive electrical devices, including medical health detection, wearable electronics, and intelligent packaging fields.

Recently, electroactive biomass‐based hydrogels have attracted great attention for flexible supercapacitor electrodes due to its porous, renewable, earth‐abundant, low‐cost, and environmentally friendly characters. However, it is challenging to facilely prepare biomass‐based hydrogels with simultaneously possesses high mechanical strength and excellent electrochemical performance. In this work, the lignosulfonate/polypyrrole (Lig/PPy) hydrogel (LP54) is obtained. In order to further improve the mechanical strength and electrochemical performance of LP54, functionalized porous carbon nanospheres/lignosulfonate/polypyrrole hydrogel (FPCSLP54) is prepared by introducing a trace of FPCS (≈4.5 wt%) fabricated by hydrothermal treatment the mixture of PCS and pyrrole into the prepared LP54 system. FPCS can be uniformly anchored into Lig/PPy framework. The LP54 and FPCSLP54 exhibit compressive strength of 6.0 and 9.3 kPa with the water content of 94.9% and 94.3%, respectively. Meanwhile, as‐prepared LP54 and FPCSLP54 are separately assembled into symmetric flexible supercapacitors with cellulose/H2SO4 hydrogel electrolytes, which exhibit superior areal capacitance (463 and 522 mF cm−2), good rate capability and outstanding energy density (41.2 and 72.5 µWh cm−2). Remarkably, flexible supercapacitors present outstanding electrochemical stability even suffering 1000 bending cycles. In this work, the strategy to construct electroactive biomass‐based hydrogels is contributed and a new method to enhance the properties of hydrogels is provided.

The development of a novel preparation strategy for 3D porous network structures with an aligned channel or wall is always in challenge. Herein, a 3D porous network composed of an aligned graphenebased wall is fabricated by a confined self-assembly strategy in which holey reduced graphene oxide (HrGO)/lignin sulfonate (Lig) composites are orientedly anchored on the framework of the Lig/single-wall carbon nanotube (Lig/SWCNT) hydrogel by vacuum-assisted filtration accompanied with confined self-assembly and followed with hydrothermal treatment. After freeze drying, the obtained ultralight Lig/SWCNT/HrGO al aerogel exhibits excellent shape memory properties and can roll back to the original shape even if suffering from a high compressive strain of 86.2%. Furthermore, the as-prepared aerogel used as a water-driven artificial muscle shows powerful driving force and can lift ultrahigh weight cargo that is 1030.6 times its own weight. When the prepared Lig/SWCNT/HrGO al aerogel is used as a pressure sensor, it also exhibits high sensitivity (2.28 kPa −1 ) and a wide detection region of 0.27−14.1 kPa. Additionally, the symmetric flexible supercapacitor assembled with as-prepared aerogel films shows superior stored energy performance that can tolerate 5000 cycles of bending. The present work not only fabricates a high-performance multifunctional material but also develops a new strategy for the preparation a wood-like 3D porous aligned wall network structure.

Three-dimensional (3D) carbon nanotube-based porous networks have received considerable attention as active nanomaterials for flexible/wearable sensor applications due to their excellent conductivity and mechanical flexibility. Herein, ultralight, biocompatible, and conductive SWCNT/tannic acid (TA) and Mg 2+ /SWCNT/TA aerogels have been facilely fabricated using TA as a dispersion reagent and crosslinker and Mg 2+ to introduce a metal−phenolic network. The construction of a SWCNT@ TA core−shell structure and the low CNT concentration of SWCNT/TA 3:3 contribute to a high linear sensitivity of 432 kPa −1 in a wide pressure range (0.014−28 kPa), while Mg 2+ modulation endows Mg 2+ /SWCNT/TA 1:1 with an ultrahigh linear sensitivity of 13662 kPa −1 in a pressure range of 0.014−1.05 kPa. The superior sensing performance of as-prepared aerogels, including high sensitivity, wide working range, low detection limit (14 Pa), and fast stimuli-response (200−300 ms), enables them to detect tiny changes in human biosignals and imperceptible vibration, which show great potential in applications of health monitoring, human− machine interfaces, and various flexible electronics.

Wood-inspired HCNF@Lig introduced into MXenes constructing a nacre-like material with high mechanical strength and excellent flexibility used as a flexible supercapacitor.

To endow high mechanical strength and thermal stability aramid nanofiber (ANF) with novel functionality will lead to great applications. Herein, a strategy to generate covalent-bonds among components towards obtaining the...