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

Abstract

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...

Elevated temperature performance of high voltage Li1+yMn1.5Ni0.5O4−xFx spinel in window-shifted Li-ion cells

“…As opposed to the general acceptance of LTO as a passivation-free material due its 1.55V potential above the carbonate-based electrolytes reduction potential, passivation was evidenced at the surface of LTO [62,63]. However, significant gassing observed in LTO-based cells with the release of H 2 , CO and CO 2 may prevent its use in commercial applications [63][64][65][66].…”

Challenges of Spinel Li4Ti5O12 for Lithium‐Ion Battery Industrial Applications

“…H 2 and CO are produced during electrochemical reactions. Fell et al [147] further proved that the H 2 is not directly decomposed from the H 2 O molecule using an elemental tracer method with heavy water (D 2 O). [12,18,145,146] However, the formation of H 2 is controversial.…”

“…However, according to a series comparison tests, Wu et al found that moisture contributes less to cell swelling. Fell et al further proved that the H 2 is not directly decomposed from the H 2 O molecule using an elemental tracer method with heavy water (D 2 O). They found that the cells with a certain amount of DMC solvent having much more D 2 O in the electrolyte showed no observable D 2 and minimal H‐D signals, indicating that the hydrogen gas was generated by the co‐reduction of DMC and water.…”

In-situ measurements of mechanical and volume change of LiCoO2 lithium-ion batteries during repeated charge–discharge cycling by using digital image correlation

“…In practice, it is known that the chemical compositions of the active materials vary with charge-discharge cycles, which may result in strain and volume change of electrode, the increasing of its impedance, and the deteriorating of individual commercial LIB capacity. Finally, it would lead to the serious imbalance of the electrochemical properties (discharging capacity, open circuit voltage (OCV), and cell impedance) [4][5][6][7][8][9]. Furthermore, the accumulated strain and stress due to the electrode swelling upon cycling may induce crack nucleation and propagation, and other failure in batteries [10][11][12].…”