The lithium metal battery is strongly considered to be one of the most promising candidates for high-energy-density energy storage devices in our modern and technology-based society. However, uncontrollable lithium dendrite growth induces poor cycling efficiency and severe safety concerns, dragging lithium metal batteries out of practical applications. This review presents a comprehensive overview of the lithium metal anode and its dendritic lithium growth. First, the working principles and technical challenges of a lithium metal anode are underscored. Specific attention is paid to the mechanistic understandings and quantitative models for solid electrolyte interphase (SEI) formation, lithium dendrite nucleation, and growth. On the basis of previous theoretical understanding and analysis, recently proposed strategies to suppress dendrite growth of lithium metal anode and some other metal anodes are reviewed. A section dedicated to the potential of full-cell lithium metal batteries for practical applicatio...

Toward Safe Lithium Metal Anode in Rechargeable Batteries: A Review.

Metal oxide nanostructures are promising electrode materials for lithium-ion batteries and supercapacitors because of their high specific capacity/capacitance, typically 2-3 times higher than that of the carbon/graphite-based materials. However, their cycling stability and rate performance still can not meet the requirements of practical applications. It is therefore urgent to improve their overall device performance, which depends on not only the development of advanced electrode materials but also in a large part "how to design superior electrode architectures". In the article, we will review recent advances in strategies for advanced metal oxide-based hybrid nanostructure design, with the focus on the binder-free film/array electrodes. These binder-free electrodes, with the integration of unique merits of each component, can provide larger electrochemically active surface area, faster electron transport and superior ion diffusion, thus leading to substantially improved cycling and rate performance. Several recently emerged concepts of using ordered nanostructure arrays, synergetic core-shell structures, nanostructured current collectors, and flexible paper/textile electrodes will be highlighted, pointing out advantages and challenges where appropriate. Some future electrode design trends and directions are also discussed.

Recent Advances in Metal Oxide-based Electrode Architecture Design for Electrochemical Energy Storage

Hybrid porous nanowire arrays composed of strongly interacting Co3O4 and carbon were prepared by a facile carbonization of the metal–organic framework grown on Cu foil. The resulting material, possessing a high surface area of 251 m2 g–1 and a large carbon content of 52.1 wt %, can be directly used as the working electrode for oxygen evolution reaction without employing extra substrates or binders. This novel oxygen evolution electrode can smoothly operate in alkaline solutions (e.g., 0.1 and 1.0 M KOH), affording a low onset potential of 1.47 V (vs reversible hydrogen electrode) and a stable current density of 10.0 mA cm–2 at 1.52 V in 0.1 M KOH solution for at least 30 h, associated with a high Faradaic efficiency of 99.3%. The achieved ultrahigh oxygen evolution activity and strong durability, with superior performance in comparison to the state-of-the-art noble-metal/transition-metal and nonmetal catalysts, originate from the unique nanowire array electrode configuration and in situ carbon incorporati...

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Metal–Organic Framework Derived Hybrid Co3O4-Carbon Porous Nanowire Arrays as Reversible Oxygen Evolution Electrodes

Microscale supercapacitors are promising alternative energy-storage devices; however, their use has been limited by the need for complicated fabrication techniques. This work reports the scalable fabrication of graphene supercapacitors with planar geometry that achieve power densities of up to 200 W cm−3.

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Scalable fabrication of high-power graphene micro-supercapacitors for flexible and on-chip energy storage

We developed two-step solution-phase reactions to form hybrid materials of Mn3O4 nanoparticles on reduced graphene oxide (RGO) sheets for lithium ion battery applications. Mn3O4 nanoparticles grown selectively on RGO sheets over free particle growth in solution allowed for the electrically insulating Mn3O4 nanoparticles wired up to a current collector through the underlying conducting graphene network. The Mn3O4 nanoparticles formed on RGO show a high specific capacity up to ~900mAh/g near its theoretical capacity with good rate capability and cycling stability, owing to the intimate interactions between the graphene substrates and the Mn3O4 nanoparticles grown atop. The Mn3O4/RGO hybrid could be a promising candidate material for high-capacity, low-cost, and environmentally friendly anode for lithium ion batteries. Our growth-on-graphene approach should offer a new technique for design and synthesis of battery electrodes based on highly insulating materials.

Mn3O4-Graphene Hybrid as a High Capacity Anode Material for Lithium Ion Batteries

This Review provides a brief summary of the most recent research developments in the fabrication and application of one-dimensional ordered conducting polymers nanostructure (especially nanowire arrays) and their composites as electrodes for supercapacitors. By controlling the nucleation and growth process of polymerization, aligned conducting polymer nanowire arrays and their composites with nano-carbon materials can be prepared by employing in situ chemical polymerization or electrochemical polymerization without a template. This kind of nanostructure (such as polypyrrole and polyaniline nanowire arrays) possesses high capacitance, superior rate capability ascribed to large electrochemical surface, and an optimal ion diffusion path in the ordered nanowire structure, which is proved to be an ideal electrode material for high performance supercapacitors. Furthermore, flexible, micro-scale, threadlike, and multifunctional supercapacitors are introduced based on conducting polyaniline nanowire arrays and their composites. These prototypes of supercapacitors utilize the high flexibility, good processability, and large capacitance of conducting polymers, which efficiently extend the usage of supercapacitors in various situations, and even for a complicated integration system of different electronic devices.

Conducting Polymer Nanowire Arrays for High Performance Supercapacitors

An All‐Solid‐State Flexible Micro‐supercapacitor on a Chip

In this paper, a new integrated multifunctional flexible device called the Energy Storage Smart Window (ESS window) was designed and fabricated. The proposed ESS window comprises an integrated supercapacitor and electrochromism function in one flexible device using ordered polyaniline nanowire arrays as electrodes. The ESS window showed high areal capacitance and high stability as a supercapacitor, and in situ optical measurements proved its electrochromic function. Furthermore, the ESS window can be integrated with a conventional solar cell to form a smart device system, which can simultaneously harvest, store, and use renewable energy efficiently.

Integrated energy storage and electrochromic function in one flexible device: an energy storage smart window

Single-walled carbon nanotubes and chitosan composite yarn is prepared using a wet-spinning method After thermal treatment, mesoporous all-carbon yarn is obtained Based on this material, flexible all-solid-state yarn micro-supercapacitors are fabricated Electrochemical results show high specific capacitance and energy density, good rate capability and stable cycling life Results of this research offer prospect for application in portable and wearable electronics © 2014 WILEY-VCH Verlag GmbH & Co KGaA, Weinheim

High-performance all-carbon yarn micro-supercapacitor for an integrated energy system.

In this study, a flexible supercapacitor based on cloth-supported single-walled carbon nanotubes (SWCNTs) and a conducting polyaniline (PANI) nanowire array composite electrode is designed and assembled. A non-woven wiper cloth is used as a flexible substrate to produce a conductive SWCNT/cloth composite by dip coating it in the SWCNT ink. PANI nanowire arrays are then successfully deposited onto the surface of the SWCNT/cloth composite through dilute polymerization to obtain the PANI/SWCNT/cloth composite electrode, which is used to assemble the flexible supercapacitor directly. The PANI/SWCNT/cloth electrode for flexible supercapacitors possesses the merits of large capacitance (410 F g−1), high rate capability, and good stability, which may lead to its future potential application in high-performance flexible devices.

Haiping Wu

Papers

Conducting Polymer Nanowire Arrays for High Performance Supercapacitors

An All‐Solid‐State Flexible Micro‐supercapacitor on a Chip

Integrated energy storage and electrochromic function in one flexible device: an energy storage smart window

High-performance all-carbon yarn micro-supercapacitor for an integrated energy system.

Flexible supercapacitors based on cloth-supported electrodes of conducting polymer nanowire array/SWCNT composites