Ziqiang Shao

Cellulose nanofiber– graphene all solid-state flexible supercapacitors

Cellulose nanofibers are selected as nano-spacers, electrolyte nano-reservoirs and hierarchical nanostructure makers of CNF–RGO hybrid aerogel. The CNF–RGO hybrid aerogel based flexible supercapacitor exhibits high capacitance (207 F g−1). Taking its higher capacitance, low cost and environmentally friendly nature, they have great potential for use in flexible supercapacitors.

Cellulose nanofibers/reduced graphene oxide flexible transparent conductive paper

The cellulose nanofibers (CNFs) paper exhibit high visible light transmittance, high mechanical strength, and excellent flexibility. Therefore, CNFs paper may be an excellent substrate material for flexible transparent electronic devices. In this paper, we endeavor to prepare CNFs-based flexible transparent conductive paper by layer-by-layer (LbL) assembly using divalent copper ions (Cu(2+)) as the crosslinking agent. The thickness of the reduced graphene oxide (RGO) active layer in the CNFs paper can be controlled by the cycle times of the LbL assembly. CNFs/[RGO]20 paper has the sheet resistances of ∼2.5 kΩ/□, and the transmittance of about 76% at a wavelength of 550 nm. Furthermore, CNFs/[RGO]20 paper inherits the excellent mechanical properties of CNFs paper, and the ultimate strength is about 136 MPa. CNFs-based flexible transparent conductive paper also exhibits excellent electrical stability and flexibility.

Cellulose nanofibers/multi-walled carbon nanotube nanohybrid aerogel for all-solid-state flexible supercapacitors

In recent years, much effort has been dedicated to achieve environmentally friendly, low cost, and excellent performance energy storage devices. In this work, cellulose nanofibers (CNFs)/multi-walled carbon nanotubes (MWCNTs) hybrid aerogels are prepared from CNFs/MWCNTs hydrogels by supercritical CO2 drying using CNFs as an effective, environmentally friendly, and steady dispersant of MWCNTs. All-solid-state flexible supercapacitors are fabricated using CNFs/MWCNTs hybrid aerogel film as the electrode material and charge collector. One-dimensional CNFs can effectively prevent the aggregation of MWCNTs, significantly enhance the re-wettability, and improve the utilization efficiency of the mesopores. Therefore, CNFs/MWCNTs hybrid aerogel film-based all-solid-state flexible supercapacitors exhibit excellent electrochemical properties: the specific capacitance is about 178 F g−1. The flexible supercapacitors also exhibit excellent cyclic stability. Our work provides a novel method using low cost, and environmentally friendly CNFs to realize the full potential of the MWCNTs in an assembled bulk form. Taking its low cost and environmentally friendliness, CNFs/MWCNTs hybrid aerogel has great potential as the electrode material for all-solid-state flexible supercapacitors.

The transparency and mechanical properties of cellulose acetate nanocomposites using cellulose nanowhiskers as fillers

Cellulose nanowhiskers (CNWs) were chemically modified by acetylating to obtain acetylated cellulose nanowhiskers (ACNWs) which could be well dispersed in acetone. The chemical modification was limited only on the surface of CNWs which was confirmed by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Surface substitution degree of ACNWs was evaluated to be 0.45 through X-ray photoelectron spectroscopy (XPS). Fully bioresource-based nanocomposite films were manufactured by incorporation of ACNWs into cellulose acetate (CA) using a casting/evaporation technique. Scanning electron microscope (SEM) demonstrated that ACNWs dispersed well in the CA matrix, which resulted in high transparency of all CA nanocomposites. The tensile strength, Young’s modulus and strain at break of all CA nanocomposites exhibited simultaneous increase in comparison with neat CA matrix. At the content of 4.5 wt% ACNWs, the tensile strength, Young’s modulus and strain at break of the CA nanocomposite film were increased by 9, 39, and 44 % respectively.

Cellulose nanofiber/single-walled carbon nanotube hybrid non-woven macrofiber mats as novel wearable supercapacitors with excellent stability, tailorability and reliability

Non-woven macrofiber mats are prepared by simply controlling the extrusion patterns of cellulose nanofiber/single-walled carbon nanotube suspensions in an ethanol coagulation bath, and drying in air under restricted conditions. These novel wearable supercapacitors based on non-woven macrofiber mats are demonstrated to have excellent tailorability, electrochemical stability, and damage reliability.

Synthesis and electrospinning carboxymethyl cellulose lithium (CMC-Li) modified 9,10-anthraquinone (AQ) high-rate lithium-ion battery

New cellulose derivative CMC-Li was synthesized, and nanometer CMC-Li fiber was applied to lithium-ion battery and coated with AQ by electrospinning. Under the protection of inert gas, modified AQ/carbon nanofibers (CNF)/Li nanometer composite material was obtained by carbonization in 280 °C as lithium battery anode materials for the first time. The morphologies and structures performance of materials were characterized by using IR, (1)H NMR, SEM, CV and EIS, respectively. Specific capacity was increased from 197 to 226.4 mAhg(-1) after modification for the first discharge at the rate of 2C. Irreversible reduction reaction peaks of modified material appeared between 1.5 and 1.7 V and the lowest oxidation reduction peak of the difference were 0.42 V, the polarization was weaker. Performance of cell with CMC-Li with the high degree of substitution (DS) was superior to that with low DS. Cellulose materials were applied to lithium battery to improve battery performance by electrospinning.

Highly transparent and colour-tunable composite films with increased quantum dot loading

Transparent films incorporated with quantum dots are promising light conversion materials for many cutting-edge technologies including light-emitting diodes and luminescent solar concentrators. In this work, we demonstrated that a combination of water soluble quantum dots and ultrathin cellulose nanofibers is an advantageous strategy to fabricate highly emissive thin films of tens of micrometers. By varying the composition of quantum dots, these thin films exhibit tunable photoluminescence emissions, ranging from blue to red as well as white light. Because of the inherent nanoscale phase separation of cellulose nanofibers, the loading content of quantum dots can be increased up to 50 wt%, which results in a significant increase of the refractive index. The combination of high refractive index (∼1.56), colour-tunable emissions (450–650 nm) and high transparency (∼80%, at a wavelength longer than the absorption band of quantum dots) makes them promising candidates for photonic and optoelectronic devices.

Electrospun carboxymethyl cellulose acetate butyrate (CMCAB) nanofiber for high rate lithium-ion battery.

Cellulose derivative CMCAB was synthesized, and nanometer fiber composite material was obtained from lithium iron phosphate (LiFePO4, LFP)/CMCAB by electrospinning. Under the protection of inert gas, modified LFP/carbon nanofibers (CNF) nanometer material was obtained by carbonization in 600°C. IR, TG-DSC, SEM and EDS were performed to characterize their morphologies and structures. LFP/CNF composite materials were assembled into lithium-ion battery and tested their performance. Specific capacity was increased from 147.6 mAh g(-1) before modification to 160.8 mAh g(-1) after modification for the first discharge at the rate of 2C. After 200 charge-discharge cycles, when discharge rate was increased from 2C to 5C to 10C, modified battery capacity was reduced from 152.4 mAh g(-1) to 127.9 mAh g(-1) to 106 mAh g(-1). When the ratio was reduced from 10C to 5C to 2C, battery capacity can be quickly approximate to the original level. Cellulose materials that were applied to lithium battery can improve battery performance by electrospinning.

Transparent, flexible and luminescent composite films by incorporating CuInS2 based quantum dots into a cyanoethyl cellulose matrix

Transparent luminescent composite films were fabricated by incorporating CuInS2 based quantum dots (QDs) into a cyanoethyl cellulose (CEC) matrix.

Using a fully recyclable dicarboxylic acid for producing dispersible and thermally stable cellulose nanomaterials from different cellulosic sources

We fabricated cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) from different cellulose materials (bleached eucalyptus pulp (BEP), spruce dissolving pulp (SDP) and cotton based qualitative filter paper (QFP) using concentrated oxalic acid hydrolysis and subsequent mechanical fibrillation (for CNFs). The process was green as acid can be easily recovered, and the prepared cellulose nanomaterials were carboxylated and thermally stable. In detail, the CNC yield from the different materials was similar. After hydrolysis, the DP of the cellulose materials decreased substantially, whereas the mechanical fibrillation of the cellulosic solid residues (CSRs) did not dramatically reduce the DP of cellulose. CNCs with different aspect ratios were produced from different starting materials by oxalic acid hydrolysis. The CNCs and CNFs obtained from BEP and QFP possessed more uniform dimensions than those from SDP. On the other hand, CNFs derived from SDP presented the best suspension stability. FTIR analyses verified esterification of cellulose by oxalic acid hydrolysis. The results from both XRD and Raman spectroscopy indicated that whereas XRD crystallinity of CNCs from BEP and QFP did not change significantly, there was some change in Raman crystallinity of these samples. Raman spectra of SDP CNCs indicated that the acid hydrolysis preferably removed cellulose I portion of the samples and therefore the CNCs became cellulose II enriched. TGA revealed that the CNCs obtained from QFP exhibited higher thermal stability compared to those from BEP and SDP, and all the CNCs possessed better thermal stability than that of CNCs from sulfuric acid hydrolysis. The excellent properties of prepared cellulose nanomaterials will be conducive to their application in different fields.