Investigation on Li4Ti5O12 batteries developed for hybrid electric vehicle

Wu, Kai; Yang, Jun; Zhang, Yao; Wang, Chenyun; Wang, Deyu

doi:10.1007/s10800-012-0442-0

Cited by 94 publications

(91 citation statements)

References 20 publications

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“…17 One of the main differences between the use of graphite and LTO anodes, is the fact, that LTO-containing Li-ion pouch bag cells frequently tend to swell after several cycles or during storage in the charged state, whereby the main gas component is H 2 (≈ 50 wt%). 3,[16][17][18][19][20][21] In contrast to that, pouch cells containing graphite electrodes do not show such strong gassing upon cycling or storage. 13,22 Joho et al 8 performed DEMS measurements on graphite half-cells with different concentrations of water (250 ppm, 1000 ppm and 4000 ppm H 2 O), demonstrating that the amount of C 2 H 4 decreases with increasing H 2 O concentration and that the formation of H 2 increases with the water content.…”

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confidence: 88%

Gas Evolution at Graphite Anodes Depending on Electrolyte Water Content and SEI Quality Studied by On-Line Electrochemical Mass Spectrometry

Bernhard

Metzger

Gasteiger

2015

J. Electrochem. Soc.

153

179

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The gas evolution during the formation of graphite electrodes is quantified by On-line Electrochemical Mass Spectrometry (OEMS) for dry electrolyte (< 20 ppm H 2 O) and 4000 ppm H 2 O containing electrolyte to mimic the effect of trace water during the formation process. While the formation in dry electrolyte mainly shows ethylene (C 2 H 4 ) from the reduction of ethylene carbonate (EC) and small amounts of hydrogen (H 2 ), the formation in water-containing electrolyte yields large amounts of H 2 and considerable amounts of CO 2 in addition to the expected C 2 H 4 evolution. We could show that a protective solid-electrolyte interphase (SEI) layer formed by pre-cycling the graphite electrode in 2% vinylene carbonate (VC) containing electrolyte can reduce the H 2 evolution in watercontaining electrolyte by a factor of 7.5 compared to a pristine graphite electrode. Consequently, the ability of graphite electrodes to form an SEI prevents excessive gassing from trace water, which, e.g., is observed for non-SEI forming lithium titanate ( Today's Li-ion batteries usually employ graphite or lithium titanate Li 4 Ti 5 O 12 (LTO) as anode material. Graphite electrodes are known to have an irreversible capacity loss upon the first charge, i.e., during the first Li + -ion intercalation into the layered graphite structure. 1 This effect is related to the formation of the so called solid-electrolyte interphase (SEI) and depends strongly on the electrolyte composition and the electrode potential.2 The capacity loss is explained by the reduction of electrolyte components on the graphite surface, which irreversibly consumes Li + -ions and forms the protective and passivating SEI layer on the negative electrode. On the one hand, the SEI inhibits further reduction reactions on the anode surface due to its electronically insulating nature, on the other hand it is still permeable for Li + -ions, allowing for Li + intercalation. [3][4][5][6][7][8][9][10][11] Recent work by the group of Brett Lucht showed that lithium ethylene dicarbonate (LEDC) and LiF are the main constituents of the SEI layer on graphite, when ethylene carbonate-based electrolytes are used, independent of the type of lithium salt. 12 The main gaseous components formed during electrolyte reduction on graphite anodes are ethylene (C 2 H 4 ), hydrogen (H 2 ) and other hydrocarbons like propylene (depending on the cyclic carbonate, which is used in the electrolyte mixture).13-15 When employing the common alkyl carbonate electrolytes containing ethylene carbonate (EC), dimethylcarbonate (DMC), diethylcarbonate (DEC) and/or ethyl methyl carbonate (EMC) with LiPF 6 , no carbon dioxide (CO 2 ) formation is observed during the SEI formation. 10In contrast to graphite, LTO is generally believed to possess no SEI protection, since its lithiation potential (1.55 V Li ) is too high to allow reduction of electrolyte components. Thus, LTO is more prone to gassing from trace water and other impurities in the alkyl carbonate electrolyte.16 Gassing studies with LTO as anode material...

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confidence: 88%

Gas Evolution at Graphite Anodes Depending on Electrolyte Water Content and SEI Quality Studied by On-Line Electrochemical Mass Spectrometry

Bernhard

Metzger

Gasteiger

2015

J. Electrochem. Soc.

153

179

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“…Recent research suggests reactions involving a Ti 3+ /Ti 4+ redox couple combined with electrolyte parasitic reactions. 6,[8][9][10][11] Other research suggests residual moisture in the electrodes and electrolyte causes gas formation.12-16 Literature has consistently identified redox gases from the anode as being dominated by H 2, CO, CO 2 , olefins and alkanes. 12,17,18 Recent work from the Dahn group found that LCO/LTO based cells with moisture levels up to 1000 ppm show increased swelling.…”

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Investigation of the Gas Generation in Lithium Titanate Anode Based Lithium Ion Batteries

Fell

Sun

Hallac

et al. 2015

J. Electrochem. Soc.

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Lithium titanate (LTO), Li 4 Ti 5 O 12 is a promising material for energy storage due to its high-rate capabilities and safety. However, gas generation, which can be observed under high-temperature operation, present a challenge to the large-scale application of lithium ion batteries made from LTO anodes. Here we analyzed sources of gas generation in an LTO system through isotopic tagging of primary suspected sources of H 2 . Specifically, we added small amounts of heavy water (D 2 O) to the electrolyte, D 2 O to the LTO electrode, or deuterated dimethyl carbonate (DMC) to the electrolyte. Upon cycling, the isotopic tagging method enables the separation of deuterated from non-deuterated gas products using combined gas chromatography and mass spectroscopy (GC/MS) analysis. The results demonstrate that cell performance and generation of H 2 are both strongly related to moisture content within the cells. Cells with deuterated DMC in the electrolyte show negligible breakdown as determined by the lack of H-D/D 2 gas production when compared to samples that contain D 2 O added into the electrode or electrolyte. These results indicate that the primary source of gas generation in LTO-based cells is residual moisture in the electrodes and electrolyte, reinforcing the importance of low-moisture processing conditions for LTO-based lithium ion batteries. The rechargeable lithium ion battery is one of the most important energy storage technologies today as the power source in hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs) and full electric vehicles (EVs) as well as for large-scale storage of renewable energy.1 Current lithium ion batteries typically utilize a graphite anode because of the low potential vs Li, good cycle life and good rate capability. However, safety is a major issue that hinders the wide scale usage of lithium ion batteries in automobiles. At elevated temperatures using graphite anodes, for example, the solid electrolyte interphase (SEI) between the non-aqueous electrolyte and the graphite surface becomes less stable and may even decompose at temperatures as low as 60• C. 2,3 Lithium ion batteries containing lithium titanate (LTO) anodes, Li 4 Ti 5 O 12 , are promising energy storage systems for their higher rate capabilities, safety, and long cycle-life, owing to their zero volumetric growth during lithiation 4,5 and higher anode voltage compared to graphite. Gas generation is a common phenomenon leading to the degradation of battery performance in Li-ion batteries. In LTO specifically, the gas generation and associated swelling, which are accelerated under high-temperature operation, present a challenge to the widespread application of lithium ion batteries made from LTO anodes. 6,7 Much research has focused on gas evolution in LTO anode based cells. It is well known that much of the gas generation can be attributed to chemical decomposition and redox decomposition of the electrolyte solvents on the anode or cathode. A well-defined mechanism for gas generation from LTO based cell...

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“…Lithium titanate (LTO; Li 4 Ti 5 O 12 ) has emerged as an alternative negative electrode material to graphite and has been widely studied because of its excellent rate performance [16][17][18][19]. Lithium ions are inserted into the spinel lattice (Li 4 Ti 5 O 12 ) at 1.55 V (vs. Li/ Li + ).…”

Section: Introductionmentioning

confidence: 99%

Effect of Pre-Cycling Rate on the Passivating Ability of Surface Films on Li₄Ti₅O₁₂ Electrodes

Jung

Hah²,

Lee

et al. 2017

Journal of Electrochemical Science and Technology

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A comparative study was performed on the passivating abilities of surface films generated on lithium titanate (LTO; Li) electrodes during pre-cycling at two different rates. The surface film deposited at a faster pre-cycling rate (i.e., 0.5 C) is irregularly shaped and unevenly covers the LTO electrode. Owing to the incomplete coverage of the protective film, this LTO electrode exhibits poor passivating ability. Additional electrolyte decomposition and concomitant film deposition occur during subsequent charge/discharge cycles. As a result of the thick surface film, severe cell polarization occurs and eventually causes cell failure. However, pre-cycling the Li/LTO cell at a slower rate (0.1 C) improves cell polarization and capacity retention; this occurs because the surface film uniformly covers the LTO electrode and provides strong passivation. Accordingly, there is no significant film deposition during subsequent charge/discharge cycling. Additionally, self-discharge is reduced during high-temperature storage.

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Investigation on Li4Ti5O12 batteries developed for hybrid electric vehicle

Cited by 94 publications

References 20 publications

Gas Evolution at Graphite Anodes Depending on Electrolyte Water Content and SEI Quality Studied by On-Line Electrochemical Mass Spectrometry

Gas Evolution at Graphite Anodes Depending on Electrolyte Water Content and SEI Quality Studied by On-Line Electrochemical Mass Spectrometry

Investigation of the Gas Generation in Lithium Titanate Anode Based Lithium Ion Batteries

Effect of Pre-Cycling Rate on the Passivating Ability of Surface Films on Li₄Ti₅O₁₂ Electrodes

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Investigation on Li4Ti5O12 batteries developed for hybrid electric vehicle

Cited by 94 publications

References 20 publications

Gas Evolution at Graphite Anodes Depending on Electrolyte Water Content and SEI Quality Studied by On-Line Electrochemical Mass Spectrometry

Gas Evolution at Graphite Anodes Depending on Electrolyte Water Content and SEI Quality Studied by On-Line Electrochemical Mass Spectrometry

Investigation of the Gas Generation in Lithium Titanate Anode Based Lithium Ion Batteries

Effect of Pre-Cycling Rate on the Passivating Ability of Surface Films on Li4Ti5O12 Electrodes

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Effect of Pre-Cycling Rate on the Passivating Ability of Surface Films on Li₄Ti₅O₁₂ Electrodes