Synthesis of iron phosphate powders by chemical precipitation route for high-power lithium iron phosphate cathodes

Clean and efficient synthesis of LiFePO4 cathode material using titanium white waste and calcium dihydrogen phosphate

Large amounts of titanium white waste are generated in the production of titanium dioxide using sulphate method, which in turn can be used to prepare LiFePO4 cathode material, thereby reducing environmental risks and achieving resource recovery. However, a key challenge lies in the elimination of impurities. In this work, a cost-efficient and straightforward approach based on phase transformation during hydrothermal treatment was proposed to utilize titanium white waste with calcium dihydrogen phosphate for the preparation of LiFePO4 cathode material. The content of Fe in the leachate was enriched to 81.5 g/L after purification, while 99.9 % of Ti and 98.36 % of Al and were successfully removed. In the subsequent process for Fe/P mother liquor preparation, the losses of Fe and P were only 5.82 % and 2.81 %, respectively. The Fe and P contents of the synthesized FePO4 product were 29.47 % and 17.08 %, respectively, and the Fe/P molar ratio was 0.986. Crystal phase of the product matched well with standard iron phosphate, and the lamellar microstructure of FePO4 was uniform with the particle size ranging from 3 to 5 μm. Moreover, the contents of impurities in the product were far below the standard. The initial discharge of LiFePO4 synthesized by the iron phosphate was 160.6 mAh.g-1 at 0.1C and maintained good reversible capacity after 100 cycles. This work may provide new strategy for preparing LiFePO4 cathode material from industrial solid waste.

Sodium Super Ionic Conductor-Type Hybrid Electrolytes for High Performance Lithium Metal Batteries

Composite solid electrolytes (CSEs), composed of sodium superionic conductor (NASICON)-type Li_1+xAl_xTi_2-x(PO₄)₃ (LATP), poly (vinylidene fluoride-hexafluoro propylene) (PVDF-HFP), and lithium bis (trifluoromethanesulfonyl)imide (LiTFSI) salt, are designed and fabricated for lithium-metal batteries. The effects of the key design parameters (i.e., LiTFSI/LATP ratio, CSE thickness, and carbon content) on the specific capacity, coulombic efficiency, and cyclic stability were systematically investigated. The optimal CSE configuration, superior specific capacity (~160 mAh g^-1), low electrode polarization (~0.12 V), and remarkable cyclic stability (a capacity retention of 86.8%) were achieved during extended cycling (>200 cycles). In addition, with the optimal CSE structure, a high ionic conductivity (~2.83 × 10^-4 S cm^-1) was demonstrated at an ambient temperature. The CSE configuration demonstrated in this work can be employed for designing highly durable CSEs with enhanced ionic conductivity and significantly reduced interfacial electrolyte/electrode resistance.

Analysis of the osteogenic and mechanical characteristics of iron (Fe2+/Fe3+)-doped β‑calcium pyrophosphate

The calcium phosphate is the main mineral constituent of bone. Although there has been significant amount of research on finding ideal synthetic bone, no suitable scaffold material has yet been found. In this investigation, the iron doped brushite (CaHPO₄·2H₂O) has been investigated for osteogenic potential and mechanical properties. The synthesis of iron-oxide doping in the form of Fe^2+,3+-ions were carried out using the solution based method in which the ammonium hydrogen phosphate and calcium nitrate solutions were used in stoichiometric ratio for synthesizing CaHPO₄·2H₂O, with doping concentrations of Fe^2+,3+-ions between 5 mol% and 30 mol%. The synthesized powders were analysed using X-ray powder diffraction, FTIR, SEM and Raman spectroscopic techniques. The heat treatment of synthesized powder was carried out at 1000 °C in air for 5 h, and it was found that the dominant crystalline phase in samples with <20 mol% was β-CPP, which also formed an iron-rich solid solution phase. Increasing the concentrations of Fe^2+,3+-ions enhances the phase fraction of FePO₄ and amorphous phase. Amongst the Fe^2+,3+-doped β-CPP minerals, it was found that the 10 mol% Fe^2+,3+-doped β-CPP offers the best combination of bio-mechanical and osteogenic properties as a scaffold for bone tissue regenerative engineering.