Ex situ X-­Ray absorption study of Li-­rich layered cathode material Li[Li0.2Mn0.56Ni0.16Co0.08]O2


Autoria(s): Wang, Diandian
Contribuinte(s)

Giorgetti, Marco

Data(s)

26/07/2013

31/12/1969

Resumo

The Li-rich layered transition metal oxides (LLOs) Li2MnO3-LiMO2 (M=Mn, Co, Ni, etc.) have drawn considerable attention as cathode materials for rechargeable lithium batteries. They generate large reversible capacities but the fundamental reaction mechanism and structural perturbations during cycling remain controversial. In the present thesis, ex situ X-ray absorption spectroscopy (XAS) measurements were performed on Li[Li0.2Mn0.56Ni0.16Co0.08]O2 at different stage of charge during electrochemical oxidation/reduction. K-edge spectra of Co, Mn and Ni were recorded through a voltage range of 3.7-4.8V vs. Li/Li+, which consist of X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). Oxidation states during initial charge were discussed based on values from literature as well as XANES analysis. Information about bond distance, coordination number as well as corresponding Debye-Waller factor were extracted from Gnxas analysis of raw data in the EXAFS region. The possibility of oxygen participation in the initial charge was discussed. Co and Ni prove to take part in the oxidation/reduction process while Mn remain in the tetravalent state. The cathode material appears to retain good structural short-range order during charge-discharge. A resemblance of the pristine sample and sample 4 was discovered which was firstly reported for similar compounds.

Formato

application/pdf

Identificador

http://amslaurea.unibo.it/5773/1/Diandian_wang_tesi.pdf

Wang, Diandian (2013) Ex situ X-­Ray absorption study of Li-­rich layered cathode material Li[Li0.2Mn0.56Ni0.16Co0.08]O2. [Laurea magistrale], Università di Bologna, Corso di Studio in Advanced spectroscopy in chemistry [LM-DM270] <http://amslaurea.unibo.it/view/cds/CDS0885/>

Relação

http://amslaurea.unibo.it/5773/

Direitos

info:eu-repo/semantics/openAccess

Palavras-Chave #Li-rich layered transition metal oxides (LLOs), XANES, EXAFS, charge compensation mechanism #scuola :: 843899 :: Scienze #cds :: 0885 :: Advanced spectroscopy in chemistry [LM-DM270] #sessione :: prima
Tipo

PeerReviewed