化学研究报告2013-09-05 2:58 AM

Microparticle Electrodes and Single Particle Microbatteries: Electrochemical and in Situ MicroRaman Spectroscopic Studies - Accounts of Chemical Research (ACS Publications)

Studies of the intrinsic electrochemical, structural, and electronic propertiesof microparticles of energy storage materials can provide much needed insight into the factors that control various aspects of the performance of technical electrodes for battery applications. This Account summarizes efforts made in our laboratories toward the development and implementation of methods for the in situ electrical, optical, and spectroscopic characterization of microparticles of a variety of such materials, including Ni hydroxide, Zn, carbon, and lithiated Mn and Co oxides. In the case of Ni hydroxide, the much darker appearance of NiOOH compared to the virtually translucent character of virgin Ni(OH)2 allowed for the spatial and temporal evolution of charge flow within spherical microparticles of Ni(OH)2 to be monitored in real time during the first scan toward positive potentials using computer-controlled video imaging. In situ Raman scattering measurements involving single microparticles of Zn harvested from a commercial Zn|MnO2 battery revealed that passive films formed in strongly alkaline solutions by stepping the potential from 1.55 V to either 0.7 or 0.8 V vs SCE displayed a largely enhanced feature at ca. 565 cm–1 ascribed to a longitudinal optical phonon mode of ZnO, an effect associated with the presence of interstitial Zn and oxygen deficiencies in the lattice. In addition, significant amounts of crystalline ZnO could be detected only for passive films formed at the same two potentials after the electrodes had been roughened by a single passivation–reduction step. Quantitative correlations were found in the case of LiMn2O4 and KS-44 graphite between the Raman spectral properties and the state of charge. In the case of KS-44, a chemometrics analysis of the spectroscopic data in the potential region in which the transition between dilute phase 1 and phase 4 of lithiated graphite is known to occur made it possible to determine independently the fraction of each of the two phases present as a function of potential without relying on the coulometric information. Also featured in this Account are methods we developed for the assembly and electrochemical characterization of Zn|MnO2 and nickel|metal-hydride Ni|MH alkaline batteries incorporating single microparticles of the active materials. As evidenced from the data collected, the voltage–time profiles for constant current operation for both types of devices were found to be similar to those of commercially available batteries involving the same chemistries. The ability to monitor the state of charge of individual particles based strictly on spectroscopic data is expected to open exciting new prospects for visualizing the flow of charge within electrodes in Li-ion batteries, an area that is being vigorously pursued in our laboratories.

KEYWORDS

SHARE & LIKE

COMMENTS

ABOUT THE AUTHOR

化学研究报告

0 Following 0 Fans 0 Projects 69 Articles

SIMILAR ARTICLES

Going in vivo, including living cells and the whole body, is very important for gaining a better understanding of the mystery of life and requires spec

Read More

Polytheonamide B (1), isolated from the marine sponge Theonella swinhoei, is a posttranslationally modified ribosomal peptide (MW 5030 Da) that display

Read More

Singlet fission (SF) is a spin-allowed process in which an excited singlet state spontaneously splits into a pair of triplet excitons. This relaxation

Read More

Singlet exciton fission is the process in conjugated organic molecules bywhich a photogenerated singlet exciton couples to a nearby chromophore in the

Read More

Uridine(5′)diphospho(1)α-d-galactose (UDP-gal) provides all galactosyl units in biologically synthesized carbohydrates. All healthy cells produce UDP-g

Read More

The coupling of aryl halides with catalytically activated aryl C–H bondsprovides a desirable and atom-economical alternative to standard cross-coupling

Read More

Acenes are a class of aromatic hydrocarbons composed of linearly fused benzene rings. Noteworthy features of these molecules include their extended fla

Read More

Securing our energy future is the most important problem that humanity faces in this century. Burning fossil fuels is not sustainable, and wide use of

Read More

Certain organic materials can generate more than one electron-hole pair per absorbed photon, a property that could revolutionize the prospects for sola

Read More

Certain organic materials can generate more than one electron-hole pair per absorbed photon, a property that could revolutionize the prospects for sola

Read More