Nae-Lih Wu

Bio: Nae-Lih Wu is an academic researcher from National Taiwan University. The author has contributed to research in topics: Electrolyte & Anode. The author has an hindex of 48, co-authored 147 publications receiving 7166 citations.

Inhibition of Crystallite Growth in the Sol-Gel Synthesis of Nanocrystalline Metal Oxides

Abstract: Crystal growth upon firing of hydrous transition metal oxide gels can be effectively inhibited by replacing the surface hydroxyl group before firing with another functional group that does not condense and that can produce small, secondary-phase particles that restrict advancing of grain boundaries at elevated temperatures. Accordingly, fully crystallized SnO 2 , TiO 2 , and ZrO 2 materials with mean crystallite sizes of ∼20, 50, and 15 angstroms, respectively, were synthesized by replacing the hydroxyl group with methyl siloxyl before firing at 500°C. An ultrasensitive SnO 2 -based chemical sensor resulting from the microstructural miniaturization was demonstrated.

Enhanced Cycle Life of Si Anode for Li-Ion Batteries by Using Modified Elastomeric Binder

Abstract: Department of Chemical Engineering, Tung Hai University, Taichung, Taiwan 407Cycle-life of the particulate electrode of Si, either with or without carbon coating, for Li-ion battery has significantly beenimproved by using a modified elastomeric binder containing styrene-butadiene-rubber~SBR! and sodium-carboxyl-methyl-cellulose ~SCMC!. Compared with poly-vinylidene-fluoride~PVdF!, the (SBR 1 SCMC) mixture binder shows smaller moduli,a larger maximum elongation, a stronger adhesion strength on Cu current collector, and much smaller solvent-absorption inorganic carbonate. There were demonstrated cycle lives of .50 cycles for bare Si at 600 mAh/g or carbon-coated Si at 1000mAh/g, as contrast to <8 cycles for PVdF-bound electrode in all cases.© 2004 The Electrochemical Society. @DOI: 10.1149/1.1847685# All rights reserved.Manuscript submitted July 28, 2004; revised manuscript received September 27, 2004. Available electronically December 16,2004.

High Polarity Poly(vinylidene difluoride) Thin Coating for Dendrite-Free and High-Performance Lithium Metal Anodes

Abstract: The high-polarity β-phase poly(vinylidene difluoride) (β-PVDF), which has all trans conformation with F and H atoms located on the opposite sides of the polymer backbone, is demonstrated to be a promising artificial solid-electrolyte interphase coating on both Cu and Li metal anodes for dendrite-free Li deposition/stripping and enhanced cycling performance. A thin (≈4 µm) β-PVDF coating on Cu enables uniform Li deposition/stripping at high current densities up to 5 mA cm−2, Li-plating capacity loadings of up to 4 mAh cm−2, and excellent cycling stability over hundreds of cycles under practical conditions (1 mA cm−2 with 2 mAh cm−2). Full cells containing an LiFePO4 cathode and an anode of either β-PVDF coated Cu or Li also exhibit excellent cycling stability. The profound effects of the high-polarity PVDF coating on dendrite suppression are attributed to the electronegative F-rich interface that favors layer-by-layer Li deposition. This study offers a new strategy for the development of dendrite-free metal anode technology.

Materials for electrochemical capacitors

Abstract: Electrochemical capacitors, also called supercapacitors, store energy using either ion adsorption (electrochemical double layer capacitors) or fast surface redox reactions (pseudo-capacitors). They can complement or replace batteries in electrical energy storage and harvesting applications, when high power delivery or uptake is needed. A notable improvement in performance has been achieved through recent advances in understanding charge storage mechanisms and the development of advanced nanostructured materials. The discovery that ion desolvation occurs in pores smaller than the solvated ions has led to higher capacitance for electrochemical double layer capacitors using carbon electrodes with subnanometre pores, and opened the door to designing high-energy density devices using a variety of electrolytes. Combination of pseudo-capacitive nanomaterials, including oxides, nitrides and polymers, with the latest generation of nanostructured lithium electrodes has brought the energy density of electrochemical capacitors closer to that of batteries. The use of carbon nanotubes has further advanced micro-electrochemical capacitors, enabling flexible and adaptable devices to be made. Mathematical modelling and simulation will be the key to success in designing tomorrow's high-energy and high-power devices.

A review of electrode materials for electrochemical supercapacitors

Abstract: In this critical review, metal oxides-based materials for electrochemical supercapacitor (ES) electrodes are reviewed in detail together with a brief review of carbon materials and conducting polymers. Their advantages, disadvantages, and performance in ES electrodes are discussed through extensive analysis of the literature, and new trends in material development are also reviewed. Two important future research directions are indicated and summarized, based on results published in the literature: the development of composite and nanostructured ES materials to overcome the major challenge posed by the low energy density of ES (476 references).

Semiconductor-based Photocatalytic Hydrogen Generation

Abstract: 2.3. Evaluation of Photocatalytic Water Splitting 6507 2.3.1. Photocatalytic Activity 6507 2.3.2. Photocatalytic Stability 6507 3. UV-Active Photocatalysts for Water Splitting 6507 3.1. d0 Metal Oxide Photocatalyts 6507 3.1.1. Ti-, Zr-Based Oxides 6507 3.1.2. Nb-, Ta-Based Oxides 6514 3.1.3. W-, Mo-Based Oxides 6517 3.1.4. Other d0 Metal Oxides 6518 3.2. d10 Metal Oxide Photocatalyts 6518 3.3. f0 Metal Oxide Photocatalysts 6518 3.4. Nonoxide Photocatalysts 6518 4. Approaches to Modifying the Electronic Band Structure for Visible-Light Harvesting 6519

Carbon-based Supercapacitors Produced by Activation of Graphene

Abstract: Supercapacitors, also called ultracapacitors or electrochemical capacitors, store electrical charge on high-surface-area conducting materials. Their widespread use is limited by their low energy storage density and relatively high effective series resistance. Using chemical activation of exfoliated graphite oxide, we synthesized a porous carbon with a Brunauer-Emmett-Teller surface area of up to 3100 square meters per gram, a high electrical conductivity, and a low oxygen and hydrogen content. This sp 2 -bonded carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form primarily 0.6- to 5-nanometer-width pores. Two-electrode supercapacitor cells constructed with this carbon yielded high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes. The processes used to make this carbon are readily scalable to industrial levels.

Pseudocapacitive oxide materials for high-rate electrochemical energy storage

Abstract: Electrochemical energy storage technology is based on devices capable of exhibiting high energy density (batteries) or high power density (electrochemical capacitors). There is a growing need, for current and near-future applications, where both high energy and high power densities are required in the same material. Pseudocapacitance, a faradaic process involving surface or near surface redox reactions, offers a means of achieving high energy density at high charge–discharge rates. Here, we focus on the pseudocapacitive properties of transition metal oxides. First, we introduce pseudocapacitance and describe its electrochemical features. Then, we review the most relevant pseudocapacitive materials in aqueous and non-aqueous electrolytes. The major challenges for pseudocapacitive materials along with a future outlook are detailed at the end.