Jiguo Tu

A new cathode material for super-valent battery based on aluminium ion intercalation and deintercalation

Due to their small footprint and flexible siting, rechargeable batteries are attractive for energy storage systems. A super-valent battery based on aluminium ion intercalation and deintercalation is proposed in this work with VO2 as cathode and high-purity Al foil as anode. First-principles calculations are also employed to theoretically investigate the crystal structure change and the insertion-extraction mechanism of Al ions in the super-valent battery. Long cycle life, low cost and good capacity are achieved in this battery system. At the current density of 50 mAg−1, the discharge capacity remains 116 mAhg−1 after 100 cycles. Comparing to monovalent Li-ion battery, the super-valent battery has the potential to deliver more charges and gain higher specific capacity.

Electrochemically assembling of a porous nano-polyaniline network in a reverse micelle and its application in a supercapacitor

A polyaniline (PANI) film was electrochemically polymerized onto an ITO substrate by the pulse galvanostatic method in a reverse micelle electrolyte. The morphology of the as-prepared PANI was investigated by using a scanning electron microscope. An interesting result was that a nano-PANI was observed with a diameter of 100 nm. Further work involves investigating the potential application of the PANI films to a high performance supercapacitor electrode material. The energy density of the PANI was measured in HClO4 solution. The highest energy density of nano-PANI arrays was 116.6 W h kg−1 and kept as high 64.1 W h kg−1 at a large charge–discharge current density (10 A g−1). The cycle stability based on the PANI film electrode was investigated. The result showed that it had a low fading rate of its energy density after 500 cycles.

A long-life rechargeable Al ion battery based on molten salts

Affordable and scalable energy storage systems are necessary to mitigate the output fluctuation of an electrical power grid integrating intermittent renewable energy sources. Conventional battery technologies are unable to meet the demanding low-cost and long-life span requirements of a grid-scale application, although some of them demonstrated impressive high energy density and capacity. More recently, the prototype of an Al-ion battery has been developed using cheap electrode materials (Al and graphite) in an organic room-temperature ionic liquid electrolyte. Here we implement a different Al-ion battery in an inorganic molten salt electrolyte, which contains only an extremely low-cost and nonflammable sodium chloroaluminate melt working at 120 °C. Due to the superior ionic conductivity of the melt electrolyte and the enhanced Al-ion interaction/deintercalation dynamics at an elevated temperature of 120 °C, the battery delivered a discharge capacity of 190 mA h g−1 at a current density of 100 mA g−1 and showed an excellent cyclic performance even at an extremely high current density of 4000 mA g−1: 60 mA h g−1 capacity after 5000 cycles and 43 mA h g−1 capacity after 9000 cycles, with a coulombic efficiency constantly higher than 99%. The low-cost and safe characteristics, as well as the outstanding long-term cycling capability at high current densities allow the scale-up of this brand-new battery for large-scale energy storage applications.

A Novel Ultrafast Rechargeable Multi-Ions Battery

An ultrafast rechargeable multi-ions battery is presented, in which multi-ions can electrochemically intercalate into graphite layers, exhibiting a high reversible discharge capacity of ≈100 mAh g-1 and a Coulombic efficiency of ≈99% over hundreds of cycles at a high current density. The results may open up a new paradigm for multi-ions-based electrochemical battery technologies and applications.

Self-assembled amorphous manganese oxide/hydroxide spheres via multi-phase electrochemical interactions in reverse micelle electrolytes and their capacitive behavior

Amorphous matrices of three-dimensionally interconnected MnOx/MnOOH nano-spheres were electrochemically assembled onto a carbon substrate by a pulse galvanostatic method (PGM) in a nonionic reverse micelle electrolyte. The synthesized material showed a unique morphology which was attributed to a synergistic effect between the amphiphilic molecule based interface membrane as a soft template and the PGM approach. The transfer of the reactant was remarkably special because of the elusive thermodynamic and kinetic parameters of the interactions at the interface between the two different phases such as the polar phase–interface membrane, interface membrane–nonpolar phase and polar phase–electrode interactions. Further work involved investigations into the potential application of the assembled MnOx/MnOOH films as high performance supercapacitor electrode materials. The capacitive performance of the assembled MnOx/MnOOH was tested in a solution of 0.5 M Na2SO4. The highest specific discharge capacitance of 1659 F g−1 was achieved at a current density of 2 A g−1, and remained as high as 782 F g−1 even at a very large current density of 10 A g−1. The outstanding capacitance properties were ascribed to the ternary oxide composites forming highly porous nanostructures which guaranteed a large specific surface, full utilization of Mn oxides and a small amount of degradation of amorphous MnO2. The results indicate the feasibility of electrochemically synthesizing Mn oxides in unconventional micelle electrolytes, and their successful application in supercapacitors.

Mg–Ti co-doping behavior of porous LiFePO4 microspheres for high-rate lithium-ion batteries

The development of fast-charging lithium-ion batteries (LIBs) is an urgent necessity. Nevertheless, it is still a huge challenge to prepare superior high-rate cathode materials for LIBs. In this work, porous Mg–Ti co-doped LiFe0.985Mg0.005Ti0.01PO4 microspheres are successfully synthesized via a carbothermic reduction reaction in combination with a spray drying process, with FePO4 as the Fe and P source. Through X-ray diffraction (XRD) combined with X-ray photoelectron spectroscopy (XPS) Ar+-sputtering technology, it confirms that Mg and Ti are in the form of doping rather than surface recombination inside LiFePO4 microspheres, and the existence of Fe3+ inside the samples is confirmed as residual FePO4. Compared to the undoped sample, the porous Mg–Ti co-doped LiFePO4 microspheres show great improvement in electronic conductivity (1.58 × 10−3 S cm−1) and diffusion coefficient (5.97 × 10−9 cm s−1 for charging and 4.30 × 10−9 cm s−1 for discharging). More importantly, the porous Mg–Ti co-doped LiFe0.985Mg0.005Ti0.01PO4 microspheres show excellent high-rate capabilities, delivering a discharge capacity of 161.5, 160.3, 156.7, 147.5, 139.8 and 131.5 mA h g−1 at 0.2C, 0.5C, 1C, 3C, 5C and 8C, respectively.

A novel ordered SiOxCy film anode fabricated via electrodeposition in air for Li-ion batteries

A novel SiOxCy film is successfully fabricated by electrodeposition on a carbon paper substrate with vinyl trichlorosilane as the precursor in air. It has been found that the SiOxCy film is evenly and uniformly distributed on the carbon paper. The long-term cycling stability of the SiOxCy film anode is tested at a rate of 1 C for 1000 cycles, showing that the charge capacity decreases from 1919.8 mA h g−1 to 1020.5 mA h g−1 over 1000 cycles, suggesting good long-term cycling stability. The good cycling stability of the SiOxCy film anode is attributed to the ordered structure of the SiOxCy film. Moreover, the interwall space could provide a buffer for Si expansion during the Li insertion/extraction process, thus improving the cycle life of Si anodes.

Room temperature solid state dual-ion batteries based on gel electrolytes

The volume expansion of the electrodes and gas generation are still challenges for the current dual-ion batteries. Herein, we report a novel room temperature solid state dual-ion battery based on gel electrolytes. The dual-ion battery delivers a high reversible capacity of ∼80 mA h g−1, with excellent rate performance and long-term cycling stability. Moreover, the battery displays a high working voltage of 4.2 V, which enables to improve the application value of the battery. Typically, the problem of gas generation is further reduced by altering the charge cut-off voltage with gel electrolytes. First-principles simulations are performed to elucidate the anion intercalation behavior in a graphite cathode, demonstrating that the anion-intercalated graphite is stable without obvious distortion, and small activation energy barriers and fast ion-diffusivity are also reported. These convincing results indicate that this dual-ion battery is promising and environmentally friendly for future energy storage applications.

Flower-like Vanadium Suflide/Reduced Graphene Oxide Composite: An Energy Storage Material for Aluminum-Ion Batteries

A flower-like vanadium sulfide/reduced graphene oxide (VS4 /rGO) composite was prepared by a typical hydrothermal method and it was investigated as cathode for aluminum-ion batteries with non-inflammable and non-explosive ionic-liquid electrolytes. The charge/discharge performance measurements were performed in a voltage range of 0.1-2.0 V versus Al/AlCl4- , which gave an initial charge/discharge specific capacity af approximately 491.57 and 406.94 mA h g-1 , respectively, at a current density of 100 mA g-1 . Additionally, in the cycling performance, the discharge capacity was observed to remain over 80, 70, and 60 mA h g-1 at current densities of 100, 200, and 300 mA g-1 after 100 cycles, respectively. The result of a coulombic efficiency over 90 % after 100 cycles and high retained capacity indicate that the composite is a favorable cathode material for new rechargeable aluminum-ion batteries.

Production of Ti–Fe alloys via molten oxide electrolysis at a liquid iron cathode

This work studies the direct electrochemical preparation of Ti–Fe alloys through molten oxide electrolysis (MOE) at a liquid iron cathode. Cyclic voltammetry and potentiostatic electrolysis have been employed to study the cathodic process of titanium ions. The results show that cathodic behavior happens during the negative sweep at a potential range from −0.80 to −1.25 V (vs. QRE-Mo), corresponding to the electro-reduction of titanium ions. Importantly, Ti–Fe and titanium-rich Ti–Fe alloys have been successfully produced by galvanostatic electrolysis at different current densities of 0.15 and 0.30 A cm−2, respectively. The results show that it is feasible to directly prepare Ti–Fe alloys by the MOE method at a liquid iron cathode.