Role of Electrolytes in the Stability and Safety of Lithium Titanate-Based Batteries

Arunabh Ghosh,Fouad Ghamouss

doi:10.3389/fmats.2020.00186

Arunabh Ghosh, Fouad Ghamouss

Open Access

https://doi.org/10.3389/fmats.2020.00186

Copy DOI

Abstract

Lithium titanate (Li4Ti5O12, LTO) has emerged as an alternative anode material for rechargeable lithium-ion batteries with the promises of long cycle life, superior safety, better low-temperature performance, and higher power density compared to their graphite-based counterparts. LTO, being a “zero-strain” material, shows almost no volume change (<1%) during lithium insertion/extraction and hence offers excellent cycling stability (over 20,000 cycles). LTO anodes were initially popular with the belief that these anodes’ electrolyte-interfaces were free of any solid electrolyte interphase (SEI) layers. However, that was found to be not accurate. Rather recent studies have reported different types of deposits and layer formations on the surface of LTOs, and therefore this unexplored area got serious attention from the past few years and emerged as an important future research direction. However, these anodes, being very active catalysts, suffer from severe unwanted reactions with electrolytes, and problems like gas evolution and associated swelling of the battery pack happen. On the other hand, electrolytes were found to be one of the primary sources of these problems, as they are also reactive with both anode and cathodes, and this creates a severe stability and safety concern. The presence of moisture within the system, decomposition of the electrolyte solvents and solutes, high catalytic activities of the anode, are among the possible reasons behind the instability of an LTO based battery. Developing an appropriate chemical composition of the electrolyte, and/or modification of the electrode/electrolyte interface can provide prevention from these issues.

Highlights

The importance of lithium ion (Li+) batteries (LIBs) has been established for several decades; efforts are ongoing to refine and improve the performance of the batteries
At such a low potential, the electrolyte is reduced and a solid electrolyte interphase (SEI) layer is formed (Aurbach, 2002), which in one sense is beneficial as it stops further reaction of the anode with the electrolyte, but the layer hinders lithium ion insertion/removal, leading to a poor cycle life and irreversible capacity during the first few cycles (Winter et al, 1998)
It has been observed that the addition of specific additives to the electrolyte has greatly influenced the performance of LTO batteries by facilitating the formation of stable, protective layers on the electrode surface, such layers being considered as a form of SEI

Summary

Introduction

The importance of lithium ion (Li+) batteries (LIBs) has been established for several decades; efforts are ongoing to refine and improve the performance of the batteries. For the purpose of suppressing the gas generation of LMO//LTO/C LIB systems, a high-potential formation protocol was developed, which resulted in a stable SEI film on the surfaces of LTO/C materials.

Results

Conclusion