Rotor blade grinding and re-annealing of LiCoO2: SEM, XPS, EIS and electrochemical study

Alcántara, Ricardo; Ortiz, Gregório F.; Lavela, Pedro; Jaegermann, Wolfram; Thißen, Andreas

doi:10.1016/j.jelechem.2005.07.011

Cited by 29 publications

(23 citation statements)

References 38 publications

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“…This sub-peak has been reported to be the result of carbonate impurities on the surface of the LiCoO 2 particles. 46 This contribution emerged at significant levels upon cycling bare electrodes in LiPF 6 and LiClO 4 . A weak contribution (≈1 atomic %) with a slightly lower binding energy (535.1 eV) was observed for the coated electrode cycled in LiPF 6 .…”

Section: Resultsmentioning

confidence: 99%

XPS Investigation of the Electrolyte Induced Stabilization of LiCoO₂and “AlPO₄”-Coated LiCoO₂Composite Electrodes

Quinlan

Kwabi

et al. 2015

J. Electrochem. Soc.

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The "AlPO 4 " coating has been shown to improve the electrochemical performance of LiCoO 2 batteries. We previously showed that the "AlPO 4 " coating promotes the formation of metal fluorides, which could act as a stable surface film and protect LiCoO 2 from continuous degradation upon cycling. In this work, we removed the fluorine source in the LiPF 6 salt by using the LiClO 4 salt and investigated the effectiveness of the "AlPO 4 " coating. Interestingly, the "AlPO 4 " coating was found to improve the voltage efficiency and capacity retention when cycling in the LiPF 6 electrolyte, but was detrimental when cycling in the LiClO 4 electrolyte. XPS revealed that the "AlPO 4 " coating promotes the formation of metal fluoride in both electrolytes, with the surface film formed in LiClO 4 being more electrically resistive compared to that formed in LiPF 6 . The source of fluorine in the coated electrode cycled in LiPF 6 is largely attributed to the LiPF 6 salt whereas the source of fluorine in the coated electrode cycled in LiClO 4 is the binder PVDF. We believe that the coating could react with HF impurity in the LiPF 6 electrolyte or from the binder PVDF and form stable metal fluoride films on the surface. Lithium cobalt oxide, LiCoO 2 , is currently the most common cathode material used in lithium ion battery technology, 1,2 but only half of the theoretical capacity, ≈140 mA h g −1 , is obtained when charged to 4.2 V vs. Li + /Li. Higher capacity is obtainable if cycled to voltages greater than 4.2 V, but this was shown to result in high capacity loss.3,4 Structural instability 3,5 and reactivity of the cathode with the electrolyte 3 have both been proposed as possible mechanisms for the observed capacity fade. Surface modification via coatings with intrinsic materials by thermal treatment during the synthesis process 6 or with extrinsic materials, 7-10 is one successful method of improving performance. These cathodes with surface-modified LiCoO 2 1,2,6-11 have shown improvement when cycled to high voltages compared to bare LiCoO 2 positive electrodes. However, the origin responsible for the increased performance is not well understood. Understanding the mechanism responsible for the enhancement in cycling stability provided by the coatings/surface modification is essential to further stabilize positive electrode materials for applications that demand high cycle life such as electrical vehicles and stationary storage.Enhanced performance in cycling associated with surface coating has been attributed to phase transitions, 3,4,[12][13][14][15] The recent investigation by Dahèron et al.,18 showed that the substitution of Al for Co not only increases the ionic nature of the Co-O bond through orbital mixing, but also that the substitution reduces the basicity of the LiCoO 2 surface, thus making the surface less receptive or vulnerable to acidic attack in the electrolyte. However, this benefit can be temporary as recent work indicates that the Li-Al-Co-O surface region is consumed during cycling. 27 The "AlPO 4 "-coati...

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Section: Resultsmentioning

confidence: 99%

XPS Investigation of the Electrolyte Induced Stabilization of LiCoO₂and “AlPO₄”-Coated LiCoO₂Composite Electrodes

Quinlan

Kwabi

et al. 2015

J. Electrochem. Soc.

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“…[15,16] In order to facilitate the complete reaction of LiCoO 2 with lithium, previous modification of commercial lithium cobalt oxide is carried out by grinding and reannealing, which leads to the formation of ultrathin layered particles. [17] A detailed analysis of the changes in oxidation state and local environment of cobalt atoms in lithium test cells is achieved by using the powerful X-ray absorption spectroscopies (XAS). [18] Results and Discussion X-ray absorption near edge structure (XANES) spectroscopy is a particularly well-suited technique for providing a deep insight into the oxidation state of the absorber atoms.…”

Section: Introductionmentioning

confidence: 99%

“…[17] Below 3.0 V versus Li, raw LiCoO 2 reacts with about three Li atoms through an extended plateau located at approximately 1.25 V, followed by a continuous potential fade (Figure 3 a). According to previous studies on cobalt oxides, the plateau at approximately 1.25 V is due to a reduction process in which the metal oxide is converted into an amorphous composite matrix made of metallic nanograins and lithium oxide, and the sloping part is associated with electrolyte decomposition processes.…”

Section: Introductionmentioning

confidence: 99%

“…The exfoliation of LiCoO 2 particles is a deleterious effect, which decreases the extension of the plateau of the first discharge, while the sloping region below 0.9 V extends. The carbonatation process, induced by grinding, [17] results in a shorter current-voltage plateau that continuously decreases as the grinding time increases. The extension of the sloping region of the first discharge, corresponding to the reactions with the electrolyte, is larger for the sample ground for 20 min (193 mA h g À1 measured between 0.9 and 0.3 V) and is shorter for the sample ground for 60 min (161 mA h g À1 ).…”

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confidence: 99%

“…Then, there is an anomalous behaviour in the dependence of the extension of the sloping region with grinding time. Most probably, the thin layers obtained after 20 min of grinding [17] exhibit an enhanced reactivity near 0 V. Therefore, grinding does not allow a net improvement to the poor behaviour of LiCoO 2 concerning capacity retention, probably owing to the loss of electrical connectivity between active parts by the presence of isolating lithium carbonate impurities.…”

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confidence: 99%

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X‐ray Absorption Spectroscopic Study of LiCoO₂ as the Negative Electrode of Lithium‐Ion Batteries

Chadwick

Savin

Alcántara³

et al. 2006

ChemPhysChem

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Lithium cobalt oxide (LiCoO(2)) particles are modified using rotor blade grinding and re-annealing and used as the active electrode material versus lithium in the 3-0 V potential interval, in which a maximum capacity of 903 mA h g(-1) is achieved. X-ray absorption near edge structure spectra reveal the complete reduction of Co(3+) to Co metal at 0 V. Cell recharge leads to an incomplete reoxidation of cobalt. A maximum reversible capacity of 812 mA h g(-1) is obtained, although a poor capacity retention upon prolonged cycling may limit its application.

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Nanostructured Electrodes for Lithium Ion Batteries

Alcántara

Lavela

Vicente

et al. 2011

Solid State Electrochemistry II

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Rotor blade grinding and re-annealing of LiCoO2: SEM, XPS, EIS and electrochemical study

Cited by 29 publications

References 38 publications

XPS Investigation of the Electrolyte Induced Stabilization of LiCoO₂and “AlPO₄”-Coated LiCoO₂Composite Electrodes

XPS Investigation of the Electrolyte Induced Stabilization of LiCoO₂and “AlPO₄”-Coated LiCoO₂Composite Electrodes

X‐ray Absorption Spectroscopic Study of LiCoO₂ as the Negative Electrode of Lithium‐Ion Batteries

Nanostructured Electrodes for Lithium Ion Batteries

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Rotor blade grinding and re-annealing of LiCoO2: SEM, XPS, EIS and electrochemical study

Cited by 29 publications

References 38 publications

XPS Investigation of the Electrolyte Induced Stabilization of LiCoO2and “AlPO4”-Coated LiCoO2Composite Electrodes

XPS Investigation of the Electrolyte Induced Stabilization of LiCoO2and “AlPO4”-Coated LiCoO2Composite Electrodes

X‐ray Absorption Spectroscopic Study of LiCoO2 as the Negative Electrode of Lithium‐Ion Batteries

Nanostructured Electrodes for Lithium Ion Batteries

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Product

Resources

About

XPS Investigation of the Electrolyte Induced Stabilization of LiCoO₂and “AlPO₄”-Coated LiCoO₂Composite Electrodes

XPS Investigation of the Electrolyte Induced Stabilization of LiCoO₂and “AlPO₄”-Coated LiCoO₂Composite Electrodes

X‐ray Absorption Spectroscopic Study of LiCoO₂ as the Negative Electrode of Lithium‐Ion Batteries