PRODUCTION OF HIGH-PURITY SPHERONIZED GRAPHITE FOR LITHIUM-ION BATTERY ANODES

Abstract

Purpose. Determination and justification of the sequence of process stages for the production of spherical graphite for lithium-ion battery anodes, which ensures the minimisation of losses of high-purity material during spheronization and enables a purity of over 99.95% by mass to be achieved during the post-purification stage without altering the particle morphology or impairing their electrochemical characteristics.

Methodology. The study was carried out using samples of spheronized graphite obtained from natural graphite of the GAK-2 grade. Chemical purification of the spheronized material was performed using a sulphuric acid solution with the addition of ammonium fluoride. The chemical purity of the graphite was determined by ashing in a muffle furnace at 1050 °C followed by X-ray fluorescence analysis of the ash using an Oxford Instruments X-Supreme 8000 spectrometer. Electrochemical testing of the graphite materials was conducted in two-electrode cells with lithium counter electrodes using a 32-channel MSTAT ARBIN system.

Findings. It was established that the proposed chemical purification method for spheronized graphite enables the production of an anode material with a purity exceeding 99.95% while preserving the spherical morphology of the particles. Electrochemical studies confirmed the high stability of the obtained materials, including the achievement of a specific capacity of 365 mAh g⁻¹ during prolonged cycling.

Originality. The effectiveness of the proposed technological route for producing graphite anode materials for lithium-ion batteries has been demonstrated. The approach involves the spheronization of partially purified graphite followed by chemical post-purification of the spheronized material. For the first time, the possibility of efficient purification of spheronized graphite using dilute sulphuric acid solutions with the addition of ammonium fluoride has been demonstrated.

Practical value. The proposed technological approach to spherical graphite production reduces losses of high-purity graphite during the spheronization stage and promotes more efficient utilisation of graphite raw materials in the manufacture of anode materials for lithium-ion batteries.