Solid-State Synthesis of Nanosized LiFePO<sub>4</sub> Cathode Material by Using a Diluting Agent
Kamila Akhmetova, Batukhan Tatykayev, Zhandos Shalabayev, Natalya Khan, Fail Sultanov, Valeriya Volobuyeva, Akbar Dauletbay, Zhumabay Bakenov, Almаgul Mentbayeva
Abstract
Nanosized LiFePO 4 /C cathode material was synthesized via a facile mechanochemical activation method with the addition of a diluting agent. A diluting agent or solid diluent is an inert additive that does not react with the precursors and can be easily removed after synthesis by washing or heating. Its addition promotes the formation of nanoparticles with minimal or no agglomeration. In this study, (NH 4 ) 2 CO 3 was selected as the solid diluent for synthesizing LiFePO 4 /C nanoparticles. The structure, surface morphology, and electrochemical performance of the synthesized material were characterized using thermogravimetric analysis coupled with mass spectrometry, X-ray diffraction, X-ray photoelectron spectroscopy, electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge/discharge testing. Fourier-transform infrared and Raman spectroscopy has confirmed the formation of an intermediate complex after mechanochemical activation. The use of a solid diluent up to a certain concentration was found to effectively reduce the particle size. The optimal diluent amount was determined to be 0.2 g per 1 g of LiFePO 4 /C, resulting in particles smaller than 100 nm. This sample exhibited excellent electrochemical performance, comparable to commercial LiFePO 4 /C, with a discharge capacity of 144.48 mAh g –1 at 0.1C and 100% capacity retention after 30 cycles.