Synergistic effect of hydrogen bond and carbon coating to suppress the capacity and voltage fading in Li-Rich cathode

Abstract

The voltage and capacity degradation of high-capacity Li-rich Mn-based (LRM) batteries during cycling have been a formidable barrier to their commercial application. In this study, a modified material coated with 15 nm-thick hydroxy-rich carbon layer (C-LRM) is synthesized by hydrothermal method, and C-LRM-PAA electrode is assembled by combining C-LRM with LiPAA binder. The strong hydrogen bond formed by the rich carboxyl group in LiPAA and the hydroxyl group in C-LRM makes the components of the C-LRM-PAA electrode closely connected to avoid electrode cracking, and the coating of the carbon layer avoids the cracking of the cathode particles. Consequently, this unique combination successfully inhibits transition metal dissolution, diminishes charge transfer impedance, and augments the lithium-ion diffusion coefficient, all of which contribute to suppressing the capacity and voltage attenuation. The electrochemical performance shows that after 200 cycles at 1C, the capacity retention rate increases from 40.8 % to 75.5 %, and the voltage decay rate decreases from 2.925 mV per cycle to 2.135 mV per cycle. This provides a new perspective for the electrode design of high energy density LRM batteries.