Synthesis of high-performance Li2FeSiO4/C composite powder by spray-freezing/freeze-drying a solution with two carbon sources

Synthesis of high-performance Li₂FeSiO₄/C composite powder by spray-freezing/freeze-drying a solution with two carbon sources

Yukiko Fujita, Hiroaki Iwase, Kenji Shida, Jinsun Liao, Takehisa Fukui, Motohide Matsuda

Abstract

Li₂FeSiO₄ is a promising cathode active material for lithium-ion batteries due to its high theoretical capacity. Spray-freezing/freeze-drying, a practical process reported for the synthesis of various ceramic powders, is applied to the synthesis of Li₂FeSiO₄/C composite powders and high-performance Li₂FeSiO₄/C composite powders are successfully synthesized by using starting solutions containing both Indian ink and glucose as carbon sources followed by heating. The synthesized composite powders have a unique structure, composed of Li₂FeSiO₄ nanoparticles coated with a thin carbon layer formed by the carbonization of glucose and carbon nanoparticles from Indian ink. The carbon layer enhances the electrochemical reactivity of the Li₂FeSiO₄, and the carbon nanoparticles play a role in the formation of electron-conducting paths in the cathode. The composite powders deliver an initial discharge capacity of 195 and 137 mAh g⁻¹ at 0.1 C and 1 C, respectively, without further addition of conductive additive. The discharge capacity at 1 C is 72 mAh g⁻¹ after the 100^th cycle, corresponding to approximately 75% of the capacity at the 2nd cycle.

Keywords

Lithium-ion battery, Cathode material, Li2FeSiO4/C, Spray-freezing/freeze-drying, Nanoparticle, Composite powder