New studies refute the prevailing notion that the degradation of rechargeable battery performance is primarily due to filmy residue on the electrodes, identifying them instead as secondary consequences.
The actual cause of the decline in rechargeable battery efficiency is uncovered.
For many years, the scientific community has operated under the assumption that the performance degradation of rechargeable batteries is largely attributable to the film-like accumulations on the internal electrodes. However, recent findings have shown this perspective to be incorrect.
The presence of dendritic or arborescent lithium metal deposits on battery electrodes is now understood not to be the core reason for performance decline, but is instead a derivative effect. Today (September 28), the first-ever direct assessment of the electrical characteristics at the junction between the solid electrode and liquid electrolyte within a rechargeable battery has been published in the academic journal Nature Energy.
Conducted by researchers at the Department of Energy’s Pacific Northwest National Laboratory (PNNL), the study demonstrates that the so-called solid electrolyte interphase (SEI) is not an electrical insulator as formerly believed. Rather, it exhibits semiconductor-like behavior. This new understanding resolves long-standing uncertainties about the electrical functioning of the SEI during battery operation.
Dr. Yaobin Xu, a battery research scientist, utilizes a transmission electron microscope to scrutinize the functionality of a rechargeable battery. Credit: Photo by Andrea Starr | Pacific Northwest National Laboratory
These results have immediate ramifications for the development of more enduring batteries by optimizing the physical and electrochemical traits of the liquid electrolyte—often dubbed the lifeblood of an operational battery.
“Increased electrical conductance leads to a thicker SEI layer with complex solid lithium formations, which ultimately compromises battery efficiency,” remarked Chongmin Wang, a PNNL Laboratory Fellow and expert in battery technology who co-headed the research.
Micro-Scale Battery Research Challenges Conventional Wisdom on Rechargeable Battery Functionality
The SEI layer, thinner than a sheet of tissue paper, holds significant sway over battery performance. This thin film selectively enables the transit of charged lithium ions during discharging and regulates electron movement that provides battery power.
Initial formation of the SEI occurs during the first charging cycle and ideally remains stable for the projected lifespan of the battery. However, inspection of aging rechargeable batteries often exposes considerable accumulation of solid lithium on the negative electrodes. Until now, it was widely presumed that this led to performance decay, partly due to limitations in conducting precise measurements to verify cause and effect.
The team, led by Wang and Wu Xu, a materials scientist with PNNL’s Battery Materials and Systems Group, along with co-authors Yaobin Xu and Hao Jia, and additional collaborators from PNNL, Texas A&M University, and Lawrence Berkeley National Laboratory, addressed this gap by creating a novel method to directly measure the electrical conductivity across the SEI using an experimental setup. This involved coupling transmission electron microscopy with nanoscale manipulation of specially fabricated metal needles within the microscope. Electrical properties of the SEI layer were then measured on either copper or lithium metal using four distinct electrolyte formulations.
Measurements by the team confirmed that the SEI layer becomes semi-conductive as battery voltage escalates, exhibiting electron leakage in all cases examined.
The Results Indicate Carbon-Based Molecules Are Responsible for Electron Leakage, Shortening Battery Life
After documenting this previously unobserved semiconductor-like behavior, the researchers aimed to identify the specific components within the chemically intricate SEI responsible for the leakage of electrons.
“It was discerned that carbon-based organic elements of the SEI are inclined to leak electrons,” Xu noted.
Consequently, the study concluded that minimizing these organic elements in the SEI would prolong battery longevity.
“Even minor fluctuations in the rate of electron conduction through the SEI can lead to substantial differences in battery efficiency and cycle stability,” Wang further elaborated.
Reference: “Direct in situ measurements of electrical properties of solid–electrolyte interphase on lithium metal anodes” 28 September 2023, Nature Energy.
DOI: 10.1038/s41560-023-01361-1
Contributors to the research also included PNNL researchers Peiyuan Gao, Xia Cao, Phung M. L. Le, Mark H. Engelhard, Shuang Li, and Ji-Guang Zhang. The study received sponsorship from the DOE Office of Energy Efficiency and Renewable Energy’s Office of Vehicle Technologies under the Advanced Battery Materials Research Program and the US-Germany Cooperation on Energy Storage. Electrical and imaging analysis was conducted at the Environmental Molecular Sciences Laboratory, a nationally recognized scientific user facility sponsored by DOE’s Office of Biological and Environmental Research and located at PNNL. Additional characterization work took place at the Molecular Foundry at Lawrence Berkeley National Laboratory, supported by the DOE Office of Science, Office of Basic Energy Sciences.
Table of Contents
Frequently Asked Questions (FAQs) about Rechargeable Battery Degradation
What does the new research about rechargeable batteries claim?
The new research, conducted by the Department of Energy’s Pacific Northwest National Laboratory (PNNL), challenges the long-standing belief that filmy buildups on battery electrodes are the primary cause of performance degradation. Instead, these buildups are identified as secondary consequences.
Who led this groundbreaking research?
The research was spearheaded by a team at the Department of Energy’s Pacific Northwest National Laboratory (PNNL). Chongmin Wang, a PNNL Laboratory Fellow and battery technology expert, co-led the study.
What methods were used to come to this conclusion?
The research team employed a novel method that involved the first-ever direct measurement of electrical properties at the boundary between the solid electrode and liquid electrolyte within a rechargeable battery. This was achieved by coupling transmission electron microscopy with nanoscale manipulation of specially fabricated metal needles.
How does the solid electrolyte interphase (SEI) behave according to the research?
Contrary to earlier beliefs that the SEI is an electrical insulator, the study reveals that it behaves like a semiconductor. This finding resolves long-standing uncertainties about the electrical functioning of the SEI during battery operation.
What are the implications of these findings?
The findings have significant ramifications for the development of more enduring batteries. By understanding the real cause of degradation, engineers can now focus on optimizing the physical and electrochemical traits of the liquid electrolyte, which is often referred to as the lifeblood of an operational battery.
What components in the SEI layer are responsible for electron leakage?
The research found that the carbon-containing organic components of the SEI layer are prone to leaking electrons, thus affecting battery longevity.
Are there any future steps suggested by the research?
While the research itself does not explicitly outline future steps, the implication is that minimizing the organic components in the SEI would enable batteries to have a longer useful life. Further research could focus on this aspect for more optimized battery design.
Who sponsored the research?
The research was sponsored by the DOE Office of Energy Efficiency and Renewable Energy’s Office of Vehicle Technologies under the Advanced Battery Materials Research Program and the US-Germany Cooperation on Energy Storage.
More about Rechargeable Battery Degradation
- Pacific Northwest National Laboratory
- Department of Energy’s Office of Energy Efficiency and Renewable Energy
- Nature Energy Journal
- Advanced Battery Materials Research Program
- US-Germany Cooperation on Energy Storage
- Environmental Molecular Sciences Laboratory
- Lawrence Berkeley National Laboratory
- Texas A&M University
7 comments
Looks like the future of batteries just got a whole lot brighter. literally and metaphorically.
Science never fails to amaze. Just when you think you know something, research comes along and turns it on its head.
This changes everything in battery research, right? Im all ears for what they gonna come up with next. Engineers, your move!
Wow, this is groundbreaking stuff. Always thought it was the filmy buildup thats the culprit. Mind blown!
So cool that they can now actually measure whats going on at the electrode-electrolyte boundary. Thats some next level tech!
if this leads to longer-lasting batteries, it’s a big win for sustainability. Less waste and more efficiency, I’m all in.
never thought I’d see the day when common wisdom about batteries got flipped like this. Cant wait to see the new designs coming out.