Single-source precursors for the low-temperature preparation of rechargeable battery electrode materials.

摘要

Lithium ion batteries have revolutionized the portable electronics market and are being intensively pursued now for transportation and for stationary storage of renewable energies. As one of the most promising alternatives, sodium ion batteries are also being actively studied owing to the high abundance and low cost of sodium sources. Electrodes play a critical role in defining the overall performance of secondary batteries, while the morphologies of electrode materials greatly determine their properties. Different synthetic methods afford electrode materials with specific morphology. Compared to traditional electrode preparation techniques, the single-source precursor approach can produce materials at significantly lower temperatures, with higher product purity and composition homogeneity at the molecular level. Moreover, the technique can be utilized for the preparation of nanostructured and thin film electrode materials, which represent two favorable morphologies for improving electrode performance.;Herein, several single-source precursor systems for various electrode materials are reported. Title compounds were obtained in high yield by simple solid-state reactions employing commercially available reagents. Substantial scale-up preparations were achieved using a solution approach. Complexes are relatively stable in open air, highly volatile, and soluble in common solvents. The presence of heterometallic species in the gas phase and in solution has been investigated. All precursors were shown to exhibit clean, low-temperature decomposition that results in phase-pure target electrode materials.;In general, this work contributes to developing new synthetic methods for the preparation of lithium and sodium ion battery electrode materials. It demonstrates that certain heterometallic coordination complexes with suitable ligands can be employed as single-source precursors iv providing a viable alternative to traditional solid state approaches. Unlike previously reported examples, the single-source precursors described in this work exhibit high volatility and solubility, as well as retention of their heterometallic structures in the gas phase and in solution. The heterometallic precursors show low-temperature decomposition that results in phase-pure targeted electrode materials and enables the control of the morphology in the final products. With the great variety of ligands used in the synthesis of different compounds, this work provides practical guidelines for the rational design of single-source precursors with a proper metal:metal ratio for a specific material.