With the growing demand for electric vehicles, the need for high-safety, long-life batteries also rises. Yet the electric vehicles' demand for high energy density batteries outpaces the capabilities of the current lithium-ion batteries. Scientists are looking to develop lithium metal batteries with lithium metal as the anode because these batteries have a much higher charging capacity. However, there are safety issues with lithium-metal batteries because dendrites—spiky, metallic microstructures—form during the charging process.
A team of Chinese researchers set out to solve the problem of the lithium dendrite formation and to build high-safety, long-life lithium metal batteries. The team has successfully designed an electrolyte that suppresses the formation of the dendrites. This electrolyte delivers excellent performance in lithium metal batteries and offers solutions in the research toward building high-safety, long-life lithium metal batteries.
The team's findings are published in the journal Nano Research on October 3, 2022.
While lithium metal anodes hold great potential for high-energy storage batteries, the uncontrollable lithium dendrite growth raises significant concerns. The dendrite growth occurs when the lithium ions move and convert to one specific location on the lithium metal surface. The dendrites cause poor cycling efficiency in the battery and are a severe safety issue.
The team tackled the dendrite problem by combining the advantages of conventional electrolytes and high-concentration electrolytes. The high-concentration electrolytes overcome some of the shortcomings of conventional electrolytes, and hold strong promise for use in next-generation batteries. The electrolyte the team created delivers excellent electrochemical performance in lithium metal batteries and suppresses formation of dendrites. "Its unique structure not only promotes the uniform conversion of ions on the electrode surface but also ensures the rapid movement of ions in the electrolyte," said Chunpeng Yang, a professor at Tianjin University.
The researchers began their work by running numerical simulations to explore the effect of a negatively charged coating to induce the interfacial high-concentration electrolyte. Then as a proof-of-concept material, the researchers coated nitrogen- and oxygen-doped carbon nanosheets, that have surface negative charges, with nickel foam to create the electrode. The positively charged lithium ions are concentrated near the nitrogen- and oxygen-doped carbon electrode that is coated with nickel. This concentration of lithium ions promotes the charge transfer reactions on the electrode contribute to outstanding electrochemical cycling performances. The researchers conducted half-cell and full-cell tests on the electrode with excellent results. Their electrode performs much better than other electrodes based on pure nickel foam.
"This provides a simple principle for suppressing the lithium dendrites by simultaneously taking into account the advantages of conventional electrolyte and high-concentration electrolyte for stable Li metal anode, which may be applied to other substrates for practical metal batteries," said Yang.
Beyond coating negatively surface-charged materials on the electrode to guide the formation of interfacial high-concentrated electrolytes, the team plans to look for other ways to obtain this unique electrolyte structure as means to achieving high-performance batteries. The researchers hope to achieve the commercial application of Li metal batteries with high energy density, high safety and long life, by systematically optimizing the battery components. "Our study results could be extended to more metal-battery systems, such as sodium, zinc and magnesium metal batteries, which will contribute to the realization of large-scale energy storage for sustainable energy supply," said Yang
The research team includes Haotian Lu, Feifei Wang, and Lu Wang from Tianjin University, the Haihe Laboratory of Sustainable Chemical Transformations, and the National University of Singapore; Chunpeng Yang, from Tianjin University and the Haihe Laboratory of Sustainable Chemical Transformations; Jinghong Zhou, from East China University of Science and Technology; Wei Chen, from National University of Singapore; and Quan-Hong Yang from Tianjin University and the Haihe Laboratory of Sustainable Chemical Transformations.
This research is funded by the National Key Research and Development Program of China, the Haihe Laboratory of Sustainable Chemical Transformations, and the Fundamental Research Funds for the Central Universities.
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About Nano Research
Nano Research is a peer-reviewed, international and interdisciplinary research journal, publishes all aspects of nano science and technology, featured in rapid review and fast publishing, sponsored by Tsinghua University and the Chinese Chemical Society. It offers readers an attractive mix of authoritative and comprehensive reviews and original cutting-edge research papers. After 15 years of development, it has become one of the most influential academic journals in the nano field. In 2022 InCites Journal Citation Reports, Nano Research has an Impact Factor of 10.269 (9.136, 5 years), the total cites reached 29620, ranking first in China's international academic journals, and the number of highly cited papers reached 120, ranked among the top 2.8% of over 9000 academic journals.
About Tsinghua University Press
Established in 1980, belonging to Tsinghua University, Tsinghua University Press (TUP) is a leading comprehensive higher education and professional publisher in China. Committed to building a top-level global cultural brand, after 41 years of development, TUP has established an outstanding managerial system and enterprise structure, and delivered multimedia and multi-dimensional publications covering books, audio, video, electronic products, journals and digital publications. In addition, TUP actively carries out its strategic transformation from educational publishing to content development and service for teaching & learning and was named First-class National Publisher for achieving remarkable results.
