Zhi-Wen Chang

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 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.

Nanoengineered Ultralight and Robust All-Metal Cathode for High-Capacity, Stable Lithium–Oxygen Batteries

The successful development of Li–O2 battery technology depends on resolving the issue of cathode corrosion by the discharge product (Li2O2) and/or by the intermediates (LiO2) generated during cell cycling. As an important step toward this goal, we report for the first time the nanoporous Ni with a nanoengineered AuNi alloy surface directly attached to Ni foam as a new all-metal cathode system. Compared with other noncarbonaceous cathodes, the Li–O2 cell with an all-metal cathode is capable of operation with ultrahigh specific capacity (22,551 mAh g–1 at a current density of 1.0 A g–1) and long-term life (286 cycles). Furthermore, compared with the popularly used carbon cathode, the new all-metal cathode is advantageous because it does not show measurable reactivity toward Li2O2 and/or LiO2. As a result, extensive cyclability (40 cycles) with 87.7% Li2O2 formation and decomposition was obtained. These superior properties are explained by the enhanced solvation-mediated formation of the discharge products as well as the tailored properties of the all-metal cathode, including intrinsic chemical stability, high specific surface area, highly porous structure, high conductivity, and superior mechanical stability.

Hierarchical Co3O4 porous nanowires as an efficient bifunctional cathode catalyst for long life Li-O2 batteries

Hierarchical Co3O4 porous nanowires (NWs) have been synthesized using a hydrothermal method followed by calcination. When employed as a cathode catalyst in non-aqueous Li-oxygen batteries, the Co3O4 NWs effectively improve both the round-trip efficiency and cycling stability, which can be attributed to the high catalytic activities of Co3O4 NWs for the oxygen reduction reaction and the oxygen evolution reaction during discharge and charge processes, respectively.

High-Performance Integrated Self-Package Flexible Li–O2 Battery Based on Stable Composite Anode and Flexible Gas Diffusion Layer

With the rising development of flexible and wearable electronics, corresponding flexible energy storage devices with high energy density are required to provide a sustainable energy supply. Theoretically, rechargeable flexible Li-O2 batteries can provide high specific energy density; however, there are only a few reports on the construction of flexible Li-O2 batteries. Conventional flexible Li-O2 batteries possess a loose battery structure, which prevents flexibility and stability. The low mechanical strength of the gas diffusion layer and anode also lead to a flexible Li-O2 battery with poor mechanical properties. All these attributes limit their practical applications. Herein, the authors develop an integrated flexible Li-O2 battery based on a high-fatigue-resistance anode and a novel flexible stretchable gas diffusion layer. Owing to the synergistic effect of the stable electrocatalytic activity and hierarchical 3D interconnected network structure of the free-standing cathode, the obtained flexible Li-O2 batteries exhibit superior electrochemical performance, including a high specific capacity, an excellent rate capability, and exceptional cycle stability. Furthermore, benefitting from the above advantages, the as-fabricated flexible batteries can realize excellent mechanical and electrochemical stability. Even after a thousand cycles of the bending process, the flexible Li-O2 battery can still possess a stable open-circuit voltage, a high specific capacity, and a durable cycle performance.

A Water-/Fireproof Flexible Lithium–Oxygen Battery Achieved by Synergy of Novel Architecture and Multifunctional Separator

To meet the increasing demands for portable and flexible devices in a rapidly developing society, it is urgently required to develop highly safe and flexible electrochemical energy-storage systems. Flexible lithium-oxygen batteries with high theoretical specific energy density are promising candidates; however, the conventional half-open structure design prevents it from working properly under water or fire conditions. Herein, as a proof-of-concept experiment, a highly safe flexible lithium-oxygen battery achieved by the synergy of a vital multifunctional structure design and a unique composite separator is proposed and fabricated. The structure can effectively prevent the invasion of water from the environment and combustion, which is further significantly consolidated with the help of a polyimide and poly(vinylidene fluoride-co-hexafluoropropylene) composite separator, which holds good water resistance, thermal stability, and ionic conductivity. Unexpectedly, the obtained lithium-oxygen battery exhibits superior flexibility, water resistance, thermal resistance, and cycling stability (up to 218 cycles; at a high current of 1 mA and capacity of 4 mA h). This novel water/fireproof, flexible lithium-oxygen battery is a promising candidate to power underwater flexible electronics.

CeO 2 @NiCo 2 O 4 nanowire arrays on carbon textiles as high performance cathode for Li-O 2 batteries

The successful development of Li-O2 battery technology depends on developing a stable and efficient cathode. As an important step toward this goal, for the first time, we report the development of CeO2 nanoparticles modified NiCo2O4 nanowire arrays (NWAs) grown on the carbon textiles as a new carbon-free and binder-free cathode system. In this study, the Li-O2 battery with the CeO2@NiCo2O4 NWAs has exhibited much reduced overpotentials, a high discharge capacity, an improved cycling stability, outperforming the Li-O2 battery with NiCo2O4 NWAs. These improvements can be attributed to both the tailored morphology of discharge product and improved oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activity after CeO2 NPs deposition. To a considerable extent, this idea of cathode construction including structure design and composition optimization can provide guidance for further researches in developing more powerful cathode for Li-O2 battery.

Hybrid electrolyte with robust garnet-ceramic electrolyte for lithium anode protection in lithium-oxygen batteries

Rechargeable lithium-oxygen (Li-O2) batteries have received intensive research interest due to its ultrahigh energy density, while its cycle stability is still hindered by the high reactivity of the Li anode with oxygen and moisture. To alleviate the corrosion of the metallic lithium anodes for achieving a stable Li-O2 battery, and as a proof-of-concept experiment, a distinctive hybrid electrolyte system with an organic/ceramic/organic electrolyte (OCOE) architecture is designed. Importantly, the cycle number of Li-O2 batteries with OCOE is significantly improved compared with batteries with an organic electrolyte (OE). This might be attributed to the effective suppression of the lithium anode corrosion caused by the OE degradation and the crossover of oxygen from the cathode. We consider that our facile, low-cost, and highly effective lithium protection strategy presents a new avenue to address the daunting corrosion problem of lithium metal anodes in Li-O2 batteries. In addition, the proposed strategy can be easily extended to other metal-O2 battery systems, such as Na-O2 batteries.

In Situ CVD Derived Co-N-C Composite as Highly Efficient Cathode for Flexible Li-O2 Batteries

To promote the development of high energy Li-O2 batteries, it is important to design and construct a suitable and effective oxygen-breathing cathode. Herein, activated cobalt-nitrogen-doped carbon nanotube/carbon nanofiber composites (Co-N-CNT/CNF) as the effective cathodes for Li-O2 batteries are prepared by in situ chemical vapor deposition (CVD). The unique architecture of these electrodes facilitates the rapid oxygen diffusion and electrolyte penetration. Meanwhile, the nitrogen-doped carbon nanotube/carbon nanofiber (N-CNT/CNF) and Co/CoNx serve as reaction sites to promote the formation/decomposition of discharge product. Li-O2 batteries with Co-N-CNT/CNF cathodes exhibit superior electrochemical performance in terms of a positive discharge plateau (2.81 V) and a low charge overpotential (0.61 V). Besides, Li-O2 batteries also present a high discharge capacity (11512.4 mAh g-1 at 100 mA g-1 ), and a long cycle life (130 cycles). Meanwhile, the Co-N-CNT/CNF cathode also has an excellent flexibility, thus the assembled flexible battery with Co-N-CNT/CNF can work normally and hold a wonderful capacity rate under various bending conditions.

Photoinduced decoration of NiO nanosheets/Ni foam with Pd nanoparticles towards a carbon-free and self-standing cathode for a lithium–oxygen battery with a low overpotential and long cycle life

Constructing an air electrode with a porous structure and tunable chemical composition can provide a solution to improve the performances of Li–O2 batteries. Herein, via a facile synthesis strategy by combining electrodeposition and photoreduction, we have fabricated a free-standing cathode with palladium (Pd)-modified NiO nanosheets (NS) grown on Ni foam (PNS). The Li–O2 battery with the PNS cathode delivers a high capacity (18 900 mA h g−1 at 200 mA g−1), a much reduced charge overpotential (∼0.35 V), and a long-term cycling life (103 cycles at 200 mA g−1 and 1000 mA h g−1). These properties are due to the good activity of NiO/Pd catalyst, the highly porous structure of NiO nanosheets, and the absence of an organic binder. More importantly, film-like Li2O2 is formed via a surface growth pathway in the PNS cathode, providing a large contact area between the Li2O2 and cathode surfaces. As a benefit, the electron transfer during the charge process is facilitated, contributing to a much reduced charge overpotential.