The Origin of the Residual Carbon in LiFePO₄Synthesized by Wet Milling

Abstract

This study reports the origin of the electrochemical improvement of LiFePO4 when synthesized by wet milling using acetone without conventional carbon coating. The wet milled LiFePO4 delivers 149 mAhg -1 at 0.1 C, which is comparable to carbon coated LiFePO4 and approximately 74% higher than that of dry milled LiFePO4, suggesting that the wet milling process can increase the capacity in addition to conventional carbon coating methods. UV spectroscopy, elemental microanalysis, and evolved gas analysis are used to find the root cause of the capacity improvement during the mechanochemical reaction in acetone. The analytical results show that the improvement is attributed to the conductive residual carbon on the surface of the wet milled LiFePO4 particles, which is produced by the reaction of FeC2O4· 2H2O with acetone during wet milling through oxygen deficiency in the precursor.

The distinct role of transition metal doping for LiFePO4 cathode material

“…The beneficial wet-milling effect was also reported by Park et al using acetone as a milling agent [13]. They found a carbonaceous product from the chemical reaction of a precursor with acetone during wet milling, which left conductive layers on the particle surface.…”

Synthesis, characterization and electrochemical performance of Nb doped LiFePO4/C cathodes

“…In another work, Franger et al [5] produced same material using saccharose and boron phosphate (BPO 4 ) for enhancing electronic conductivity and reported an improved electrochemical performance. Park et al [6] observe that wet-mechanochemical activation in acetone provides approximately 74% capacity increase over dry grinding. Shin et al [7] characterized carbon coated and chromium doped LiFePO 4 materials synthesized by mechanochemical activation and calcination of lithium carbonate (Li 2 CO 3 ), iron oxalate dihydrate INTRODUCTION C. Bağcı and Ö. Akyıldız / Hittite J Sci Eng, 2018, 5 (1) 49-55 50 addition.…”