A novel high-energy-density lithium-free anode dual-ion battery and in situ revealing the interface structure evolution.

Lithium-free anode dual-ion batteries have attracted extensive studies due to their simple configuration, reduced cost, high safety and enhanced energy density. For the first time, a novel Li-free DIB based on a carbon paper anode (Li-free CGDIB) is reported in this paper. Carbon paper anodes usually have limited application in DIBs due to their poor electrochemical performance. Herein, by using a lithium bis(fluorosulfonyl)imide (LiFSI)-containing electrolyte, the battery shows outstanding electrochemical performance with a capacity retention of 96% after 300 cycles at 2C with a stable 98% coulombic efficiency and 89% capacity retention after 500 cycles at 5C with a stable coulombic efficiency of 98.5%. Moreover, the electrochemical properties of the CGDIB were investigated with a variety of in situ characterization techniques, such as in situ EIS, XRD and online differential electrochemical mass spectrometry (OEMS). The multifunctional effect of the LiFSI additive on the electrochemical properties of the Li-free CGDIB was also systematically analyzed, including generating a LiF-rich interfacial film, prohibiting Li dendrite growth effectively and forming a defective structure of graphite layers. This design strategy and fundamental analysis show great potential and lay a theoretical foundation for facilitating the further development of DIBs with high energy density.

High-Energy Density Li metal Dual-Ion Battery with a Lithium Nitrate-Modified Carbonate-Based Electrolyte.

Lithium (Li) metal is a favorable anode for most energy storage equipment, thanks to its higher theoretical specific capacity. However, nonuniform Li nucleation/growth results in large-sized and irregular dendrites generated from the Li anode, which causes rapid capacity fade and serious safety hazard, hindering its widespread practical applications. In this paper, with the aid of a lithium nitrate (LiNO3) additive in a carbonate-based electrolyte, the Li anode shows low hysteresis for in excess of 1000 h at a current density of 0.5 mA cm-2. At the same time, a Li-graphite dual-ion battery exhibits an outstanding cycling stability at 5C; after 1000 cycles, 81% of the capacity is retained. After calculation, the Li-graphite dual-ion battery shows a competitive specific energy density of 243 Wh kg-1 at a power density of 234 W kg-1. Moreover, the linear sweep voltammetry test was first performed to analyze the Li nucleation/growth mechanism and explain the effect of the LiNO3 additive. The superior electrochemical properties of the Li-graphite dual-ion battery are ascribed to the formation of smooth Li composed of Li nanoparticles and a steady solid electrolyte interface film.

Novel MnO-Graphite Dual-Ion Battery and New Insights into Its Reaction Mechanism during Initial Cycle by Operando Techniques.

Dual-ion battery complements lithium-ion batteries in terms of the use of inexpensive materials and ease to construct cells. To improve the safety and energy density of dual-ion battery, in this paper, a novel MnO-graphite dual-ion battery is reported for the first time. Microporous MnO materials are used as anode, which exhibits a low conversion potential and a low voltage hysteresis. The MnO-graphite dual-ion battery can deliver a capacity of 104 mAh g-1 at 0.5C and exhibits good rate performances and cycling stability (capacity retention >93% after 300 cycles). A mechanism is proposed to explain the irreversibility in capacity during the initial cycle by using operando X-ray diffraction in combination with online electrochemical mass spectrometry and electrochemical impedance spectroscopy.

Study on a series of novel self-assembly supramolecular solar cells based on a double-layer structured chromophore of Zn-porphyrins.

We prepared in this work an anchoring porphyrin and a series of hat-porphyrins. The zinc atom of the hat-porphyrins can be coordinated axially with the pyridine moiety of the anchoring porphyrin which is anchored on the titania surface by a carboxyl group. The structures of the assemblies were confirmed using computational calculations, transmission electron microscopy (TEM) and energy dispersive spectrometry (EDS). Solar cell devices of the monomer anchoring porphyrin and its assemblies were fabricated and the photovoltaic performances were measured under standard AM 1.5 sunlight irradiance. We found that the assembly devices showed higher JSC and lower VOC than that of the monomer anchoring porphyrin device. However, the comprehensive influence of JSC and VOC led to an enhancement in the solar-to-electric power-conversion efficiency (PCE) of the assemblies. We also studied the variation of JSC and VOC using electronic absorption and emission spectroscopy, charge extraction measurements, transient photovoltage decay measurements and electrochemical impedance spectroscopy.