Solid polymer electrolytes (SPEs) are a pathway for safe, and high energy and power lithium batteries due to their thermal stability and low vapor pressure. Although polymers can be flexible and dimensional stability, it is lithium dendritic suppression can be a challenge for any electrolyte. Conventional SPEs have both mobile cations and anions, which migrate and cause concentration polarization. The low transference number for lithium ions in an electrolyte contributes lithium concentration gradients causing concentration polarization and lithium dendrites [1,2]. Single-ion conducting SPEs have been reported to demonstrate lithium ion only conduction in the electrolyte as well as retain their high mechanical stability during cycling. However, their low ionic conductivity is due to stationary phase of the tethered anion in the polymer matrix and cation-anion complexation [3].

In this study, a cyclic carbonate neutral moiety was included in the SPE to help dissociate the lithium cation from the tethered anion matrix to increase the ionic conductivity and help form the solid electrolyte interphase (SEI) layer. The cyclic carbonate unit in the SPE is similar to the cyclic carbonate solvent in a conventional lithium ion battery and could participate in the solvation of the lithium cation in the SPE. The cyclic carbonate monomer in the SPE can participate in SEI-forming electrochemical reactions on the electrode surface and suppress undesirable side reactions and lithium dendritic growth. Satisfactory level of rate and cycling performance was achieved with the novel neutral monomers in the single-ion conducting SPEs.

[1] H. Zhang, C. Li, M. Piszcz, E. Coya, T. Rojo, L.M. Rodriguez-Martinez, M. Armand, Z. Zhou, Chem. Soc. Rev. 2017, 46, 797-815.

[2] F. Ahmed, I. Choi, M.M. Rahman, H. Jang, T. Ryu, S. Yoon, L. Jin, Y. Jin, W. Kim, ACS Appl. Mater. Interfaces 2019, 11, 34930-34938.

[3] D.-M. Shin, J.E. Bachman, M.K. Taylor, J. Kamcev, J.G. Park, M.E. Ziebel, E. Velasquez, N.N. Jarenwattananon, G.K. Sethi, Y. Cui, J.R. Long, Adv. Mater. 2020, 32, 1905771.