Gassing in Li4Ti5O12-based batteries and its remedy

Abstract

Destructive gas generation with associated swelling has been a major challenge to the large-scale application of lithium ion batteries (LIBs) made from Li4Ti5O12 (LTO) anodes. Here we report root causes of the gassing behavior, and suggest remedy to suppress it. The generated gases mainly contain H2, CO2 and CO, which originate from interfacial reactions between LTO and surrounding alkyl carbonate solvents. The reactions occur at the very thin outermost surface of LTO (111) plane, which result in transformation from (111) to (222) plane and formation of (101) plane of anatase TiO2. A nanoscale carbon coating along with a stable solid electrolyte interface (SEI) film around LTO is seen most effective as a barrier layer in suppressing the interfacial reaction and resulting gassing from the LTO surface. Such an ability to tune the interface nanostructure of electrodes has practical implications in the design of next-generation high power LIBs.

A Facile Surface Reconstruction Mechanism toward Better Electrochemical Performance of Li4Ti5O12 in Lithium‐Ion Battery

“…The hydroxyl groups are Lewis‐acid sites which are considered to be able to initiate the decomposition of electrolyte solvent. Due to this high catalytic activity, anatase‐TiO 2 is considered as an undesired phase and potentially triggers severe side reactions and gassing 34, 35. Interestingly, for the hydrothermal treated LTO with 0.008 mol L −1 Na 2 S aqueous solution, the A/L value is always zero from 4 to 12 h, indicating that Na 2 S prevents the formation of anatase‐TiO 2 phase on the LTO surface.…”

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

“…Many previous works have reported that the voltage corresponding to the reaction of LTO with lithium (1.55 V vs. Li/Li + ) is too high to reductively decompose electrolytes. However, recent studies have demonstrated that electrolyte decomposition does occur and generates surface films on the LTO surface, even when the cell is operated within the stability window of the common salts and solvents used in LIBs [23][24][25][26][27][28]. Song et al [27] reported the formation of a surface film on an LTO surface, which is significantly enhanced by the presence of conductive carbon in the composite LTO electrodes.…”

Molten Salt Synthesis of Different Ionic Radii Metallic Compounds Doped Lithium Titanate Used in Li-Ion Battery Anodes

“…) and the inherently sluggish lithium-ion diffusion coef cient of bulk LTO greatly limit its rate capability, as well as its practical implementation [4][5][6][7][8][9] . The improvement for the rate performance of Li 4 Ti 5 O 12 anode have been widely studied over the past decade, which can be roughly divided into two strategies.…”