Reasons for capacity fading of LiCoPO4 cathodes in LiPF6 containing electrolyte solutions

Markevich, Elena; Sharabi, Ronit; Gottlieb, Hugo E.; Borgel, Valentina; Fridman, K.; Salitra, Gregory; Aurbach, Doron; Semrau, G.; Schmidt, Michael A.; Schall, N.; Bruenig, C.

doi:10.1016/j.elecom.2011.11.014

Cited by 144 publications

(125 citation statements)

References 12 publications

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“…Thus, in the following experiments, the anodic decomposition of conductive carbon and ethylene carbonate is monitored by 12 CO/ 12 CO 2 , while the anodic decomposition of the 13 C-labeled carbon coating can be tracked exclusively by the formation of 13 CO/ 13 CO 2 . Figure 4 depicts the ion currents, I Z , normalized by the 36 Ar isotope current, I 36 (Figure 4a) shows the normalized ion current signals (I Z /I 36 ) derived from the anodic oxidation of the 13 C carbon coating ( 13 CO 2 and 13 CO, purple lines) as well as from the conductive carbon and the ethylene carbonate ( 12 CO 2 and 12 CO, magenta lines) after baseline correction. The middle panel (Figure 4b) shows the same data after smoothing, correction for mass fractionation, and conversion into units of [ppm], using a calibration gas (see Experimental Section for details on mass fractionation and calibration).…”

Section: C-coating Oxidation In H 2 O-free Electrolyte-mentioning

confidence: 99%

“…19 To avoid signal fluctuations due to minor pressure/temperature changes, all mass signals were normalized to the ion current of the 36 Ar isotope. The cell is first held at OCV for 2 h, followed by a linear sweep voltammetry (LSV) procedure at a scan rate of 0.05 mV/s (Series G300 potentiostat, Gamry, USA) from 3.3 to 5.3 V vs. Li/Li + .…”

Section: On-line Electrochemical Mass Spectrometry (Oems)mentioning

confidence: 99%

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Carbon Coating Stability on High-Voltage Cathode Materials in H₂O-Free and H₂O-Containing Electrolyte

Metzger

Sicklinger

Haering

et al. 2015

J. Electrochem. Soc.

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Carbon coatings on cathode materials with low electrical conductivity like phospho-olivines LiMPO 4 (M = 3d-transition metal) are known to improve their performance in Li-ion batteries. However, at high potentials and in the presence of water, the stability of carbon coatings on high-voltage materials (e.g., LiCoPO 4 ) may be limited due to the anodic oxidation of carbon. In this work, we describe the synthesis of LiFePO 4 (LFP) with an isotopically labeled 13 C carbon coating (characterized by Raman spectroscopy, electrical conductivity, and charge/discharge rate capability tests) as a model compound to study the anodic stability of carbon coated cathode materials in ethylene carbonate-based electrolytes. We characterize the degradation of the 13 C carbon coating by On-line Electrochemical Mass Spectrometry (OEMS) through the 13 CO 2 and 13 CO signals in order to differentiate the anodic oxidation of the coating ( 13 C) from the oxidation of electrolyte, conductive carbon, and binder (all 12 C) in the electrode. The oxidation of the carbon coating takes place at potentials ≥ 4.75 V for electrolyte without H 2 O (< 20 ppm) and ≥ 4.5 V for electrolyte with 4000 ppm H 2 O, and it is strongly enhanced for H 2 O-containing electrolyte. The extent of carbon coating oxidation over 100 h at 4.8 and 5.0 V vs. Li/Li + (25 • C) is projected on the basis of our OEMS data, suggesting that carbon coatings have insufficient stability at such high cathodic potentials. Furthermore, our results prove the in situ formation of H 2 O during the anodic decomposition of ethylene carbonate-containing electrolyte. The H 2 O formation is monitored via the detection of gaseous POF 3 , which is formed from the reaction of Li-ion batteries are extensively investigated as energy storage devices for electric vehicles (EVs) due to their high energy density and reasonable life time.1 In order to make EVs competitive with gasoline or diesel cars, and to eventually reduce CO 2 emissions by the electrification of personal mobility, many fundamental challenges still need to be overcome. In contrast to NMC and other layered oxides, phospho-olivines like LFP and LCP suffer from very poor electrical conductivity which limits their rate capability, i.e., their performance at high charge/discharge rates. 7 In the case of LFP, its poor electrical conductivity can be overcome by using small primary particles (0.1-0.5 μm) in combination with an electrically conductive very thin carbon coating (thickness 1-2 nm) 8 applied to the primary particles using different kinds of precursors.7,9 While uncoated LFP samples either show very poor rate capability or low capacity at rates as low as 0.1 C, 10-12 Lou et al. 13 showed that carbon coated LFP can reach 116 mAh/g LFP at high rates of 10 C (theoretical capacity: 170 mAh/g LFP ).3 Even when the current is increased to 30 C, the discharge capacity can still reach 75 mAh/g LFP , and in the 100 th cycle the capacity loss is only 2.3%. 14 presented a carbon coated LFP which is able to reach discharge capacities of 1...

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Section: C-coating Oxidation In H 2 O-free Electrolyte-mentioning

confidence: 99%

Section: On-line Electrochemical Mass Spectrometry (Oems)mentioning

confidence: 99%

Carbon Coating Stability on High-Voltage Cathode Materials in H₂O-Free and H₂O-Containing Electrolyte

Metzger

Sicklinger

Haering

et al. 2015

J. Electrochem. Soc.

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show abstract

“…The capacity gradually decreased with cycling and the capacity fade and the low Coulomb efficiency would be caused by decomposition of the electrolyte at elevated potential, which have been reported. 9,10 All-solid-state cells of In/LCP-LTP-AB were assembled. Figure 5 shows the charge-discharge curves of all-solid-state cells of In/LCP-LTP-AB, and the measurements were conducted at a current density of 0.013 mA cm ¹2 at 25°C.…”

Section: Resultsmentioning

confidence: 99%

“…F ¹ ions attack to P-O bonds in LCP and then LCP decomposes, eventually leading to rapid capacity fading of batteries. 9,10 Therefore, solid electrolytes which do not decompose at high potential are expected to be applied to the cells with LCP. A few articles about all-solid-state cells using LCP as active materials have been reported, [11][12][13][14] but it is quite difficult to operate all-solid-state cells using LCP active materials as lithium ion secondary batteries.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Composites with LiCoPO4 Electrode and LiTi2(PO4)3 Electrolyte for Bulk-type All-solid-state Lithium Batteries

et al. 2015

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All-solid-state cells with LiCoPO 4 (LCP) active material with high redox potential of 4.8 V (vs. Li + /Li) were fabricated and the cells operated as a lithium secondary battery at room temperature. The composite electrodes of LCP active material and LiTi 2 (PO 4 ) 3 (LTP) electrolyte with large contact area were synthesized in the media of oleic acid and paraffin wax by heat treatment at 700°C. The prepared LCP-LTP-Acetylene black (AB) composites were applied to electrochemical cells with a conventional organic liquid electrolyte and a sulfide solid electrolyte. The all-solid-state cells using the positive electrode composed of the LCP-LTP-AB composite and the sulfide electrolyte showed the initial discharge capacity of 50 mAh g −1 at 4.8 V (vs. Li + /Li). The cells using the electrodes without LTP and the sulfide electrolyte were difficult to operate, suggesting that formation of close contacts between LCP and LTP, and additional ion conduction paths to LCP-LTP particles are effective in increasing capacities in all-solid-state cells.

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“…This material, however, shows the capacity fading during charge-discharge cycling in commercialized LiPF 6 based electrolyte solutions because of a nucleophilic attack of F ¹ anions on the P atoms of the electrode surface. 2,3 A Li 2 O-Al 2 O 3 -TiO 2 -P 2 O 5 (LATP) solid electrolyte with NASICON-type structure possesses high electrochemical stability especially at high voltage (applicable potential range: 2.8-6 V vs. Li/Li + ). 4 Therefore, the allsolid-state lithium-ion batteries (ASS-LIB) using ceramics electrolytes as LATP are desired for the future application of the highvoltage LiCoPO 4 positive electrode.…”

Section: Introductionmentioning

confidence: 99%

Application of LiCoPO4 Positive Electrode Material in All-Solid-State Lithium-Ion Battery

2014

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Submicron particles of high voltage LiCoPO 4 are prepared by sucrose-aided combustion synthesise as a preliminary arrangement for the construction of all-solid-sate lithium-ion battery. The obtained LiCoPO 4 was assembled with Li 2 O-Al 2 O 3 -TiO 2 -P 2 O 5 (LATP) solid electrolyte using spark plasma sintering (SPS) process in order to form enhanced electrical contacts. The reversible charge/discharge capacity of LiCoPO 4 was obtained by cyclic voltammetry with a sweep rate of 0.5 mV s −1 at 150°C. It would be due to the enhanced interfacial contact between LiCoPO 4 and LATP electrolyte without any voids, which was observed by the cross-sectional SEM images.

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Reasons for capacity fading of LiCoPO4 cathodes in LiPF6 containing electrolyte solutions

Cited by 144 publications

References 12 publications

Carbon Coating Stability on High-Voltage Cathode Materials in H₂O-Free and H₂O-Containing Electrolyte

Carbon Coating Stability on High-Voltage Cathode Materials in H₂O-Free and H₂O-Containing Electrolyte

Preparation of Composites with LiCoPO<sub>4</sub> Electrode and LiTi<sub>2</sub>(PO<sub>4</sub>)<sub>3</sub> Electrolyte for Bulk-type All-solid-state Lithium Batteries

Application of LiCoPO4 Positive Electrode Material in All-Solid-State Lithium-Ion Battery

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Reasons for capacity fading of LiCoPO4 cathodes in LiPF6 containing electrolyte solutions

Cited by 144 publications

References 12 publications

Carbon Coating Stability on High-Voltage Cathode Materials in H2O-Free and H2O-Containing Electrolyte

Carbon Coating Stability on High-Voltage Cathode Materials in H2O-Free and H2O-Containing Electrolyte

Preparation of Composites with LiCoPO<sub>4</sub> Electrode and LiTi<sub>2</sub>(PO<sub>4</sub>)<sub>3</sub> Electrolyte for Bulk-type All-solid-state Lithium Batteries

Application of LiCoPO4 Positive Electrode Material in All-Solid-State Lithium-Ion Battery

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Carbon Coating Stability on High-Voltage Cathode Materials in H₂O-Free and H₂O-Containing Electrolyte

Carbon Coating Stability on High-Voltage Cathode Materials in H₂O-Free and H₂O-Containing Electrolyte