Lithium-ion (Li-ion) batteries with high energy density are essential for running electric and hybrid cars, as well as for powering the next devices and power grids. These Li-ion batteries use transition metal oxide-based cathodes with a high energy density.
Among numerous investigated potential materials, the LiNi1/3Mn1/3Co1/3O2 cathode has been shown to deliver the best performance at a high potential of 4.5 V versus Li/Li+ with high reversible capacity.
The carbonate species in commercial electrolytes, ethylene carbonate, and diethyl carbonate, however, experience a severe oxidative breakdown at such high potentials. As a result, the cathode surface develops a thick layer of cathode electrolyte interphase (CEI), substantially impairing its performance.
As a result, scientists have looked into electrolyte additives as a means of limiting performance degradation by stabilizing and concealing the cathode surface. Options now on the market, however, present risks to both safety and the environment.
Recently, a team of researchers, led by Professor Noriyoshi Matsumi from Japan Advanced Institute of Science and Technology (JAIST), microbially synthesized 2,5-dimethyl-3,6-bis(4-aminobenzyl)pyrazine (DMBAP), a bio-based compound, as a potential additive for stabilizing the LiNi1/3Mn1/3Co1/3O2 cathodes. In contrast to current additives, DMBAP is sustainable, eco-friendly, economical, and non-toxic, which distinguishes their method.
The team comprised Former Senior Lecturer Rajashekar Badam, Postdoctoral Research Fellow Agman Gupta, and Doctoral Course Student Noriyuki Takamori from JAIST, along with Professor Naoki Takaya, Assistant Professor Shunsuke Masuo, and Former Graduate Student Hajime Minakawa from the University of Tsukuba in Japan. Their findings have been published in the Scientific Reports journal.
Microbially prepared pyrazine-amine compound DMBAP will boost the performance of lithium-ion secondary batteries essential for next-generation electric vehicles and drones. It will also promote the wider utilization of bio-based resources in the huge-scale automotive industry. Further, bio-based materials for energy storage devices will doubly reduce carbon dioxide emissions during manufacturing and operation.
Professor Noriyoshi Matsumi
“Although biomass-derived materials attract both researchers and society in general, their applications in electric devices, including lithium-ion batteries, are still limited. This study focuses on novel microbial metabolites, particularly the unique pyrazine-derived diamine DMBAP from the gene cluster of Pseudomonas fluorescens SBW25, discovered in collaboration with Prof. Masuo. Its role as an electrolyte additive could impact the fields of sustainability and the smart-cell industry,” explains Prof. Takaya, speaking of the motivation behind the study.
According to a preliminary theoretical analysis, the DMBAP molecule’s highest occupied molecular orbital (HOMO) is situated higher than it would be for a general-purpose electrolyte. This made it simple to oxidize at the cathode surface and formed a shield over it. The diamine in DMBAP also stopped CEI from dissolving.
For further investigation, the researchers also carried out a thorough electrochemical examination of DMBAP. The HOMO band energy was confirmed using linear sweep voltammetry, while X-ray photoelectron spectroscopy revealed C−N=C peaks indicative of oxidative electropolymerization.
Cyclic voltammetry and charge-discharge studies showed that the DMBAP additive stabilized the LiNi1/3Mn1/3Co1/3O2 cathode by improving the battery’s rate capability, cyclic stability, coulombic efficiency, and capacity retention. Furthermore, tests using dynamic electrochemical impedance spectroscopy showed that a low interfacial resistance CEI had formed.
These findings led the scientists to the conclusion that the DMBAP underwent sacrificial oxidative breakdown, resulting in the formation of an organic passivation armor on the cathode surface. As a result, the cathode’s excessive electrolyte deterioration was constrained, and the structure of the transition metal oxides was stabilized.
In effect, this virtuous phenomenon increases the operating potential window of LiNi1/3Mn1/3Co1/3O2 cathode to 4.5 V versus Li/Li+. Furthermore, DMBAP had a notable stabilizing effect on the battery system for both half-cell and full-cell configurations.
“Microbially prepared pyrazine-amine compound DMBAP will boost the performance of lithium-ion secondary batteries essential for next-generation electric vehicles and drones. It will also promote the wider utilization of bio-based resources in the huge-scale automotive industry. Further, bio-based materials for energy storage devices will doubly reduce carbon dioxide emissions during manufacturing and operation,” says Prof. Matsumi, discusses the future benefits of their work.
