Environmentally Friendly Synthesis of LiFePO₄ Using Fe–P Waste Slag and Greenhouse Gas CO₂

Abstract

An environmental-friendly and feasible route was creatively put forward to synthesize LiFePO 4 using two industrial wastes Fe-P and CO 2 from yellow phosphorus manufacture. LiFePO 4 was obtained via a one-step synthesis, in which the mixture of Fe 1.5 P, Li 2 CO 3 and H 3 PO 4 in an appropriate molar ratio was calcined at 800°C for 6h in CO 2 . The chemical reaction mechanism was investigated by TG/DSC and XRD measurements; thereby the appropriate synthesis conditions were determined. The electrochemical performances of the synthesized LiFePO 4 coated with 5.3wt% carbon were characterized by charge/discharge tests, cyclic voltammetric experiments and electrochemical impedance spectroscopic measurements, which exhibit high capacity, good cyclic capability and low impedance. Fe-P waste slag and the greenhouse gas CO 2 are successfully converted into the energy materials in this work, which improves the traditional two-step synthesis route, and provides a new perspective of LiFePO 4 production.

A Novel Strategy for the Synthesis of Fe3(PO4)2 Using Fe–P Waste Slag and CO2 Followed by Its Use as the Precursor for LiFePO4 Preparation

“…As shown in Figure a, Fe–P waste slag was composed of FeP and Fe 2 P, which was also confirmed in our previous research . There were three diffraction peaks appeared when the roasting temperature increased to 750 ° C , which agreed well with standard diffraction peaks of Fe 3 (PO 4 ) 2 (JPCDS no, 49-1087) . This indicates that Fe 1.5 P can be oxidized to Fe 3 (PO 4 ) 2 by CO 2 with a temperature above 750 ° C .…”

“…As for the yellow phosphorus industry, about 150 kg of Fe–P slags will be generated for manufacturing 1 ton of yellow phosphorus. Therefore, Fe–P slag is of low cost (no more than $500/ton,) and a huge production (more than 140,000 tons per year in western China) resource in western China. , In our previous research, Fe–P slag was determined as Fe 1.5 P, which can be treated as a mixture of FeP and Fe 2 P . Also, CO 2 is a conventional waste gas, which is gradually accumulating in air and considered as the primary greenhouse gas. , In recent years, both chemical and electrochemical methods were reported to transfer CO 2 to other chemicals, which show great potential to reduce the CO 2 concentration in air.…”

“…11 Fe−P waste slag was a solid waste sourced from the yellow phosphorus industry, which is an important chemical industry, especially in western China. 12,13 In the traditional industry, Fe−P waste slag cannot be efficiently utilized to manufacture other products, while it was commonly used as a low-quality resource for the steel-making industry. It is urgent to develop a novel method to make both Fe and P in Fe−P slag comprehensively utilized, which can benefit both the environment and the related industry.…”

“…16,17 In our previous research, we have demonstrated that Fe−P waste slag can react with Li 2 CO 3 and H 3 PO 4 under a CO 2 atmosphere to generate LiFePO 4. 13 However, the chemical mechanism insight of this process is unclear. In this work, we develop a two-step method, inspired by our previous work, of synthesizing LiFePO 4 .…”

Controllable synthesis of hierarchical micro/nano structured FePO4 particles under synergistic effects of ultrasound irradiation and impinging stream

“…Iron (III) phosphate, or FePO4 (FP), has been recognized as an appropriate and promising material, which is widely used in synthesis of the electrode precursor for lithium ion battery [21,22], in fabrication of catalyst [23,24], and in production of fertilizers [25]. According to previous stuides, preparing FP particles with micro/nano hierarchical porous structure can improve FP performance, especially as precursor for lithium ion battery [26,27].…”