Search

Abstract The commercial Nafion proton exchange membranes are most widely used in vanadium redox flow batteries (VRBs). However, their poor ion selectivity and high cost significantly limits the further development of the VRB. Herein, a green biopolymer, lignin, was firstly employed as the additive in the pristine SPEEK membrane to replace the Nafion membrane for the VRB applications. It is found that the abundant hydroxyl groups in lignin not only facilitate the dispersion of the lignin in the SPEEK matrix, but also significantly improve the proton conductivity and ion selectivity of the membrane. With these merits, the VRB single cell based on the SPEEK/lignin membrane exhibits 95.95% and 71.47% capacity retention after 100 and 300 cycles under 120 mA cm−2, respectively. Moreover, its ultrahigh coulombic efficiency (over 99.5%) and energy efficiency (over 83.5%) indicate the outstanding capability of ion selectivity and the superb protons conductivity of the membrane. The excellent stability, low cost, and remarkable device performance of the composite membrane make it a promising candidate for the next generation larger-scale VRB applications. Graphical abstract A green sulfonated poly(ether ether ketone)/lignin membrane with excellent ion selectivity is prepared to enable low cost and ultra-stable vanadium redox flow battery. fx1 Highlights • A green sulfonated poly(ether ether ketone)/lignin membrane (SPEEK/lignin) is fabricated. • The SPEEK/lignin membrane shows higher ion selectivity compared to Nafion 212 membrane. • A vanadium redox flow battery assembled with low cost SPEEK/lignin membrane shows impressive cycle life. [ABSTRACT FROM AUTHOR]

Abstract The ions exchange membrane is the key component in the redox flow battery (RFB), which determines the cycle life and the cost of RFB. Herein, we successfully prepared a low-cost K+ formed sulfonated poly(ether ether ketone) (SPEEK-K) membrane for the neutral Zn-Fe redox flow battery (ZFB) by solution casting method. The ZFB based on our SPEEK-K membrane shows outstanding performance with the coulombic efficiency and energy efficiency over 95% and 78%, respectively, at a high current density of 40 mA cm−2. The cost of SPEEK-K membrane for ZFB is also investigated, compared with commercial Nafion 117 membrane. The comprehensive performance of the SPEEK-K membrane for high energy density ZFB makes this membrane as one of the promising candidates for next generation large-scale energy storage system. Highlights • A low-coat and high-performance SPEEK-K membrane has been developed for Zn-Fe flow battery. • The stability and conductivity of the SPEEK-K is higher than that of the pristine SPEEK and commercial Nafion 117 membrane. • The Zn-Fe flow battery based on the SPEEK-K membrane exhibits high coulombic efficiency and energy efficiency. [ABSTRACT FROM AUTHOR]

Abstract A novel composite membrane blended the sulfonated poly (ether ether ketone) (SPEEK) with modified carbonaceous mudstone (SPEEK/MCM) has been developed for vanadium redox flow battery (VRB). Using a strong acidification treatment, a large amount of hydrophilic oxygen functional groups was introduced on the modified carbonaceous mudstone (MCM) particles, which has been evidenced to enhance the proton conductivity. It is found that the MCM particles help to retard the permeation of vanadium ions through the membrane. With these merits, the VRB single cell based on our novel SPEEK/MCM membrane exhibits outstanding device performance. Notably, the coulombic efficiency (CE) of the cell is as high as more than 99% and the per-cycle capacity loss is only 0.15% under a high current density of 120 mA cm−2. Our work provides a simple method to prepare low cost and high-performance membranes for VRB. More importantly, the SPEEK/MCM membrane has promising potential in other battery applications. Highlights • A composited SPEEK/ carbonaceous mudstone (SPEEK/MCM) membrane is fabricated for vanadium redox flow battery. • The SPEEK/MCM membrane shows much lower vanadium ion permeability compared to Nafion 212 membrane. • A vanadium redox flow battery assembled with a SPEEK/MCM membrane shows excellent cell performance. [ABSTRACT FROM AUTHOR]

Abstract A solar cell, capable of directly converting solar energy into electricity, bears a Shockley-Queisser limit of about 31% based on a single pn junction. In general, less than 50% of the solar irradiation spectrum (mostly in the ultraviolet and visible regions) can be utilized for the conversion. As such, the theoretical utilization rate is less than 15% in a single device, with most of the extra energy being lost as heat. It is thus appealing to enhance the energy utilization with devices that could collect the heat loss. In this study, we design and demonstrate a solar tube to realize photo-electric and photo-thermal conversions simultaneously. The key point is the use of titanium tube: (1) it has a small plasma frequency to enable wide absorption for thermal conversion; (2) it accommodates TiO 2 nanotube arrays to solve the cracking problem under tensile stress. A sandwiched membrane of high transparency and conductivity is developed for hole transport and collection. Eventually, a total energy efficiency of about 25.2% is obtained. Such a solar tube is anticipated to highly boost the utilization rate of solar energy with judiciously designed structure. Graphical abstract A solar tube integrating the photo-electric and photo-thermal conversion is developed in this study, with a total efficiency of about 25.2%. The key component is the titanium tube used, which has a small plasma frequency to enhance the light harvesting and accommodates the nanotube arrays to release the tensile stress. fx1 Highlights • A solar tube integrating the photo-electric and photo-thermal conversion is demonstrated. • The titanium having small plasma frequency is selected to enable wide absorption of photon energy for thermal conversion. • A sandwiched membrane of high transparency and conductivity is developed for tubular solar cells. [ABSTRACT FROM AUTHOR]

Abstract Graphene deposited on the surface of a carbon felt (CF) using a solution coating method has been developed as a high-performance positive electrode for an all vanadium redox flow battery (VRB). A key to obtain excellent electrochemical activity towards the VO 2 +/VO2+ redox couple is to wrap the CF using the graphene with high specific surface area and superb conductivity. It is found that the dipping times of CF into the graphene/Nafion solution significantly affect its electrochemical activity. The cyclic voltammetry (CV) results indicate that with 5 dipping times, the graphene coated CF (G/CF) exhibits the highest peak current and lowest peak potential difference towards the VO 2 +/VO2+ redox couple. More importantly, the VRB assembled with our novel G/CF cathodic electrode shows a decreased polarization during charge/discharge process compared with the control VRB with the pristine CF. Consequently, both the voltage efficiency and energy efficiency of the VRB with G/CF electrode have increased compared to the one with pristine CF. Our work provides a simple solution coating process to fabricate graphene modified CF electrode for VRB with high performance and this simple method is believed to be promising in other electrocatalysts applications. Highlights • A graphene coated carbon felt electrode (G/CF) for has been fabricated. • The graphene is homogenous dispersed on the surface of fiber of carbon felt. • The G/CF electrode displays high activity towards the VO2+/VO 2 + redox couple. • The G/CF electrode shows much better cell performance compared to pristine carbon felt electrode. [ABSTRACT FROM AUTHOR]

Polyethylene oxide (PEO)-coated hollow SnNi nanospheres (SnNi@PEO) and hollow SnNi nanospheres were obtained by a galvanic replacement method using Ni nanospheres as the sacrificial template association with surfactant (sodium dodecyl sulfate, SDS). Compared with hollow SnNi nanospheres and solid Sn nanospheres, the obtained SnNi@PEO were applied for the first time in lithium ion batteries (LIBs) and showed better electrochemical properties (reversible capacity of 560 mAh g −1 after 100 cycles with a coulomb efficiency above 98%). The excellent electrochemical performance of SnNi@PEO can be ascribed to hollow structure and PEO coating to alleviate volume expansion. To further comprehending of the mechanical stability, a diffusion-stress coupled model was solved numerically to simulate the diffusion-induced stress evolution of the single sphere during the lithiation process in LIBs. [ABSTRACT FROM AUTHOR]