No abstract

Safety issues are critical barriers to large-scale energy storage applications of lithium-ion batteries (LIBs). Using an ameliorated, thermally stable, shutdown separator is an effective method to overcome the safety issues. Herein, we demonstrate a novel, cellulosic biomass-material-blended polyvinylidene fluoride separator that was prepared using a simple nonsolvent-induced phase separation technique. This process formed a microporous composite separator with reduced crystallinity, uniform pore size distribution, superior thermal tolerance, and enhanced electrolyte wettability and dielectric and mechanical properties. In addition, the separator has a superior capacity retention and a better rate capability compared to the commercialized microporous polypropylene membrane. This fascinating membrane was fabricated via a relatively eco-friendly and cost-effective method and is an alternative, promising separator for high-power LIBs.

No abstract

Carboxymethyl cellulose nanofibrils (CMCNFs) are of great importance in the fields of sustainable chemistry and energy materials but challenging in preparation, e.g., low yield, pollution, and morphology control. In this work, CMCNFs with a quantitative yield (95%) and good morphology control were successfully achieved using a simple, low-cost, and relatively ecofriendly protocol. Water-insoluble carboxymethyl cellulose (CMC) with a low degree of substitution (DS ≤ 0.35) was obtained via moderate alkalization and etherification of cellulose raw materials and then was mechanically fibrillated to prepare CMCNFs using a microfluidizer. As the DS of the CMCNFs was increased from 0.05 to 0.35, the diameter was obviously decreased from 100 to 35 nm without changing the treelike matrix that was confirmed by TEM characterization. More importantly, there is no obvious difference in the final performance of the CMCNFs derived from different cellulose raw materials (i.e., cotton and wood) through this approach. Additionally, compared with the commercial CNFs, high stabilization of Pickering emulsions stabilized by the CMCNFs (DS = 0.23) could be achieved because of its novel morphology with a network structure, implying that the CMCNFs could potentially serve as a biofunctional stabilizer.

As one of the energy storage devices, all-solid-state flexible supercapacitors have attracted significant attention because of their high power density, low cost, high safety, low environmental impact, and long cycle life. In this study, a new type of all-solid-state flexible supercapacitor that uses cellulose nanofibers (CNFs)/molybdenum disulfide (MoS 2 )/reduced graphene oxide (RGO) hybrid aerogel film as an electrode material and charge collector and H 2 SO 4 /polyvinyl alcohol (PVA) gel as an electrolyte and separator has been demonstrated. These aerogels are prepared by supercritical CO 2 drying, which use CNFs as an effective, environmentally friendly, and steady dispersant of MoS 2 and RGO. Owing to the porous structure of the electrodes and the remarkable electrolyte absorption properties, the supercapacitors exhibit excellent electrochemical properties. The specific capacitance calculated from the cyclic voltammogram curves at a scan rate of 2 mV s À1 is about 916.42 F g À1. The capacity retention is more than 98% after 5000 charge-discharge cycles at a current density of 0.5 mA cm À2. Additionally, the areal capacitance, areal power density, and energy density of the supercapacitors are about 458.2 mF cm