N,N-dimethylacetamide-based electrolytes for Li–O2 batteries

The practical application of Li–O₂ batteries faces many limitations. For example, the growth of lithium dendrites leads to the rapid consumption of electrolyte and a large amount of lithium loss, leading to low Coulomb efficiency and safety issues.

Many methods have been used to solve these problems, including artificial protective layers, electrolyte additives, 3D composite electrodes and other means to solve the problem of lithium dendrites; and the use of non-carbon materials instead of carbon materials to improve battery stability. However, the lack of a suitable electrolyte for Li–O₂ batteries is still a challenge to overcome.

Researcher Zhang Xinbo from the Changchun Institute of Applied Chemistry, Chinese Academy of Sciences reported a new N,N-dimethylacetamide (DMA)-based electrolyte by regulating the Li⁺ solvation structure under medium concentration to promote the cycling stability of Li–O₂ batteries.

The researchers chose a salt concentration of 3M as the model system, and designed three electrolytes (1.5M LiNO₃ 1.5M LiTFSi, 1M LiNO₃ 2M LiTFSi and 0.5M LiNO₃ 2.5M LiTFSi), and used electrolytes containing 3 M LiNO₃ or 3 M LiTFSi For the control group. Experimental results and AIMD simulations show that the use of optimized electrolytes of 1 M LiNO₃ and 2 M LiTFSi in N, N dimethylacetamide can promote the formation of LiF and LiNxOy-rich SEI films, thereby protecting the lithium anode from dendrite growth and Corrosion, and achieve faster mass transfer and electrode transfer kinetics. In addition, both the symmetrical batteries (1800 hours) and the Li-O₂ batteries (180 cycles) achieve the best cycling performances in DMA-based electrolytes to our knowledge.

This study breathes new life into the electrolyte regulation strategy and paves the way for the development of alkali–O₂ batteries.

Related link: LiTFSi

Reference: X. Zhang, et al, A Renaissance of N,N-Dimethylacetamide-Based Electrolyte to Promote the Cycling Stability of Li-O2 BatteriesEnergy Environ. Sci., 2020.DOI: 10.1039/D0EE01897J