Improved cyclic stability of Li-rich/Li cells with 2-(Trimethoxysilyl)ethyl methacrylate as electrolyte additive
Layered lithium-rich oxides(LRO) materials have garnered significant attention due to their high reversible capacity and broad operating voltage range. However, the practical application of LRO materials is still restricted by the serious interfacial instability and surface structure reconstruction during long-term cyclic test. In this study, we use 2-(Trimethoxysilyl)ethyl methacrylate (TSM) as a multifunctional electrolyte additive to enhance the electrochemical performance of the Li/LRO cell. The capacity retention of the Li/LRO cell improves significantly from 67.2 % to 85.8 % after 100 cycles at 0.5C (1C = 300 mAh g -1 ) between 2.0 and 4.8 V with the addition of 2 % TSM. Under harsh conditions (with the addition of 1000 ppm H 2 O to the electrolytes), Li/LRO cell with TSM additives maintains the capacity retention of 82.5 % after 100 cycles, which is significantly higher than the cell without additives (38.0 %). Both theoretical calculations and experiments results demonstrate that TSM exhibits higher oxidation activity than the solvents, forming a uniform cathode electrolyte interphase (CEI) on the LRO surface. The TSM-derived CEI layer effectively mitigates the interfacial parasitic reactions and prevents structural degradation of LRO. Furthermore, theoretical calculations and nuclear magnetic resonance (NMR) results confirm that TSM effectively eliminates water (H 2 O) and hydrofluoric acid (HF), mitigating their adverse effects.
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