Conductive Li_(3.08)Cr_(0.02)Si_(0.09)V_(0.9)O_4 Anode Material: Novel 'Zero-Strain' Characteristic and Superior Electrochemical Li+ Storage

摘要

"Zero-strain" compounds are ideal energy-storage materials for long-term cycling because they present negligible volume change and significantly reduce the mechanically induced deterioration during charging-discharging. However, the explored "zero-strain" compounds are very limited, and their energy densities are low. Here, gamma phase Li3.08Cr0.02Si0.09V0.9O4 (gamma-LCSVO) is explored as an anode compound for lithium-ion batteries, and surprisingly its "zero-strain" Li+ storage during Li+ insertion-extraction is found through using various state-of-the-art characterization techniques. Li+ sequentially inserts into the 4c(1) and 8d sites of gamma-LCSVO, but its maximum unit-cell volume variation is only approximate to 0.18%, the smallest among the explored "zero-strain" compounds. Its mean strain originating from Li+ insertion is only 0.07%. Consequently, both gamma-LCSVO nanowires (gamma-LCSVO-NW) and micrometer-sized particles (gamma-LCSVO-MP) exhibit excellent cycling stability with 90.1% and 95.5% capacity retention after as long as 2000 cycles at 10C, respectively. Moreover, gamma-LCSVO-NW and gamma-LCSVO-MP respectively deliver large reversible capacities of 445.7 and 305.8 mAh g(-1) at 0.1C, and retain 251.2 and 78.4 mAh g(-1) at 10C. Additionally, gamma-LCSVO shows a suitably safe operating potential of approximate to 1.0 V, significantly lower than that of the famous "zero-strain" Li4Ti5O12 (approximate to 1.6 V). These merits demonstrate that gamma-LCSVO can be a practical anode compound for stable, high-energy, fast-charging, and safe Li+ storage.