Ji-Jing Xu

Tailoring deposition and morphology of discharge products towards high-rate and long-life lithium-oxygen batteries

Lithium-oxygen batteries are an attractive technology for electrical energy storage because of their exceptionally high-energy density; however, battery applications still suffer from low rate capability, poor cycle stability and a shortage of stable electrolytes. Here we report design and synthesis of a free-standing honeycomb-like palladium-modified hollow spherical carbon deposited onto carbon paper, as a cathode for a lithium-oxygen battery. The battery is capable of operation with high-rate (5,900 mAh g ⁻¹ at a current density of 1.5 A g⁻¹) and long-term (100 cycles at a current density of 300 mA g⁻¹ and a specific capacity limit of 1,000 mAh g⁻¹). These properties are explained by the tailored deposition and morphology of the discharge products as well as the alleviated electrolyte decomposition compared with the conventional carbon cathodes. The encouraging performance also offers hope to design more advanced cathode architectures for lithium-oxygen batteries.

Synthesis of Perovskite‐Based Porous La0.75Sr0.25MnO3 Nanotubes as a Highly Efficient Electrocatalyst for Rechargeable Lithium–Oxygen Batteries

Rechargeable lithium–oxygen (Li-O2) batteries have recently attracted great attention because they can theoretically store 5–10 times more energy than current lithium-ion batteries, which is essential for clean energy storage, electric vehicles, and other high-energy applications. However, to use Li-O2 batteries for practical applications, numerous scientific and technical challenges need to be surmounted. 8] In response, intensive research efforts have been made to address the challenges by incorporating metal oxides, metal nitrides, metal nanoparticles, 21] and organometallic compounds 22] as electrocatalysts in the O2 electrode. Although significant improvements in the oxygen-reductionreaction (ORR) and/or oxygen-evolution-reaction (OER) overpotentials have been achieved, there is still a demand for highly efficient electrocatalysts to further enhance the specific capacity, rate capability, and cyclic life especially at a high capacity. On the other hand, most of the catalyst performances reported thus far are tested using carbonate-based or mixed ether-carbonate-based electrolytes, which have now been shown to be not inert to the superoxide radical (O2C ) and thus are inevitably decomposed upon cell discharge/ charge. For example, Luntz and co-workers demonstrate that, when carbonate-based electrolytes are employed for LiO2 cells, the main role of the Au, Pt, and MnO2 catalysts is to catalyze the decomposition of the electrolytes. In this context, the development of OER and ORR electrocatalysts in a relatively stable electrolyte is thus of importance to realize a reversible Li-O2 battery. Compared to carbonate, ether-based electrolytes have been reported to be more suitable for Li-O2 batteries because the desired lithium peroxide is the dominant product. 29] However, there are not many reports on electrocatalysts for Li-O2 batteries with ether-based electrolytes. 10, 30, 33] Perovskite oxides have a high electronic/ionic conductivity and catalytic activity and thus could be a promising candidate as electrocatalyst for Li-O2 batteries. [33–35] Herein, we firstly propose and realize a facile, effective, and scalable strategy for preparing perovskite-based porous La0.75Sr0.25MnO3 nanotubes (PNT-LSM) by combining the electrospinning technique with a heating method. Figure 1

3D ordered macroporous LaFeO3 as efficient electrocatalyst for Li–O2 batteries with enhanced rate capability and cyclic performance

Rechargeable lithium–oxygen (Li–O2) battery is one of the most promising technologies among various electrochemical energy storage systems, while the incapability of the electrocatalyst and the inefficient transport of reactants in the O2 electrode still limit the round-trip efficiency, rate capability, and cycle stability of the Li–O2 battery. Here, three-dimensional ordered macroporous LaFeO3 (3DOM-LFO) is synthesized and employed as electrocatalyst in Li–O2 battery with relatively stable TEGDME based electrolyte. The Li–O2 cells with 3DOM-LFO show enhanced electrochemical performances, including low overpotential, high specific capacity, good rate capability and cycle stability up to 124 cycles. This enhanced catalytic performance might be due to the synergistic effect of the porosity and catalytic activity of the 3DOM-LFO catalyst.

Artificial Protection Film on Lithium Metal Anode toward Long-Cycle-Life Lithium-Oxygen Batteries

An artificial while very stable solid electrolyte interphase film is formed on lithium metal using an electrochemical strategy. When this protected Li anode is first used in a Li-O2 battery, the film formed on the anode can effectively suppress the parasitic reactions on the Li anode/electrolyte interface and significantly enhance the cycling stability of the Li-O2 battery.

Flexible lithium-oxygen battery based on a recoverable cathode

Although flexible power sources are crucial for the realization next-generation flexible electronics, their application in such devices is hindered by their low theoretical energy density. Rechargeable lithium–oxygen (Li–O2) batteries can provide extremely high specific energies, while the conventional Li–O2 battery is bulky, inflexible and limited by the absence of effective components and an adjustable cell configuration. Here we show that a flexible Li–O2 battery can be fabricated using unique TiO2 nanowire arrays grown onto carbon textiles (NAs/CT) as a free-standing cathode and that superior electrochemical performances can be obtained even under stringent bending and twisting conditions. Furthermore, the TiO2 NAs/CT cathode features excellent recoverability, which significantly extends the cycle life of the Li–O2 battery and lowers its life cycle cost.

Electrostatic Induced Stretch Growth of Homogeneous β -Ni(OH) 2 on Graphene with Enhanced High-Rate Cycling for Supercapacitors

Supercapacitors, as one of alternative energy devices, have been characterized by the rapid rate of charging and discharging, and high power density. But they are now challenged to achieve their potential energy density that is related to specific capacitance. Thus it is extremely important to make such materials with high specific capacitances. In this report, we have gained homogenous Ni(OH)2 on graphene by efficiently using of a facile and effective electrostatic induced stretch growth method. The electrostatic interaction triggers advantageous change in morphology and the ordered stacking of Ni(OH)2 nanosheets on graphene also enhances the crystallization of Ni(OH)2. When the as-prepared Ni(OH)2/graphene composite is applied to supercapacitors, they show superior electrochemical properties including high specific capacitance (1503 F g−1 at 2 mV s−1) and excellent cycling stability up to 6000 cycles even at a high scan rate of 50 mV s−1.

Macroporous Interconnected Hollow Carbon Nanofibers Inspired by Golden‐Toad Eggs toward a Binder‐Free, High‐Rate, and Flexible Electrode

Inspired by the favorable structure and shape of golden-toad eggs, a self-standing macroporous active carbon fiber electrode is designed and fabricated via a facile and scalable strategy. After being decorated with ruthenium oxide, it endows Li-O2 batteries with superior electrochemical performances.

Flexible and Foldable Li–O2 Battery Based on Paper-Ink Cathode

A flexible freestanding air cathode inspired by traditional Chinese calligraphy art is built. When this novel electrode is employed as both a new concept cathode and current collector, to replace conventional rigid and bulky counterparts, a highly flexible and foldable Li-O2 battery with excellent mechanical strength and superior electrochemical performance is obtained.

Cable‐Type Water‐Survivable Flexible Li‐O2 Battery

A novel cable-type water-survivable flexible Li-O2 battery is developed with a hydrophobic and free standing gel polymer electrolyte. Superior battery performances are successfully achieved under mechanical twisting, bending, and even immersed in water conditions, showing the high promise to power next-generation versatile flexible electronics.

In Situ Construction of Stable Tissue-Directed/Reinforced Bifunctional Separator/Protection Film on Lithium Anode for Lithium–Oxygen Batteries

To achieve a high reversibility and long cycle life for Li-O2 battery system, the stable tissue-directed/reinforced bifunctional separator/protection film (TBF) is in situ fabricated on the surface of metallic lithium anode. It is shown that a Li-O2 cell composed of the TBF-modified lithium anodes exhibits an excellent anodic reversibility (300 cycles) and effectively improved cathodic long lifetime (106 cycles). The improvement is attributed to the ability of the TBF, which has chemical, electrochemical, and mechanical stability, to effectively prevent direct contact between the surface of the lithium anode and the highly reactive reduced oxygen species (Li2 O2 or its intermediate LiO2 ) in cell. It is believed that the protection strategy describes here can be easily extended to other next-generation high energy density batteries using metal as anode including Li-S and Na-O2 batteries.