Critical evaluation of the stability of highly concentrated LiTFSI - Acetonitrile electrolytes vs. graphite, lithium metal and LiFePO4 electrodes
Artikel i vetenskaplig tidskrift, 2018

Highly concentrated LiTFSI - acetonitrile electrolytes have recently been shown to stabilize graphite electrodes in lithium-ion batteries (LIBs) much better than comparable more dilute systems. Here we revisit this system in order to optimise the salt concentration vs. both graphite and lithium metal electrodes with respect to electrochemical stability. However, we observe an instability regardless of concentration, making lithium metal unsuitable as a counter electrode, and this also affects evaluation of e.g. graphite electrodes. While the highly concentrated electrolytes have much improved electrochemical stabilities, their reductive decomposition below ca. 1.2 V vs. Li + /Li° still makes them less practical vs. graphite electrodes, and the oxidative reaction with Al at ca. 4.1 V vs. Li + /Li° makes them problematic for high voltage LIB cells. The former originates in an insufficiently stable solid electrolyte interphase (SEI) dissolving and continuously reforming – causing self-discharge, as observed by paused galvanostatic cycling, while the latter is likely caused by aluminium current collector corrosion. Yet, we show that medium voltage LiFePO 4 positive electrodes can successfully be used as counter and reference electrodes.

SEI

Highly concentrated electrolyte

Li-ion battery

Self-discharge

Al corrosion

Författare

Viktor Nilsson

Chalmers, Fysik, Kondenserade materiens fysik

Centre national de la recherche scientifique (CNRS)

Uppsala universitet

Reza Younesi

Uppsala universitet

D. Brandell

Uppsala universitet

K. Edstrom

Uppsala universitet

Centre national de la recherche scientifique (CNRS)

Patrik Johansson

Centre national de la recherche scientifique (CNRS)

Chalmers, Fysik, Kondenserade materiens fysik

Journal of Power Sources

0378-7753 (ISSN)

Vol. 384 334-341

Ämneskategorier

Oorganisk kemi

Materialkemi

Annan kemiteknik

DOI

10.1016/j.jpowsour.2018.03.019

Mer information

Senast uppdaterat

2018-09-07