Nam Ki-Hun, Wang Zhongling, Luo Jessica, Huang Cynthia, Millares Marie F, Pace Alexis, Wang Lei, King Steven T, Ma Lu, Ehrlich Steven, Bai Jianming, Takeuchi Esther S, Marschilok Amy C, Yan Shan, Takeuchi Kenneth J, Doeff Marca M
Energy Storage and Distributed Resources Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
Institute of Energy: Sustainability, Environment and Equity, Stony Brook University, Stony Brook, New York 11794, United States.
Chem Mater. 2024 Apr 30;36(9):4481-4494. doi: 10.1021/acs.chemmater.4c00085. eCollection 2024 May 14.
Four different high-entropy spinel oxide ferrite (HESO) electrode materials containing 5-6 distinct metals were synthesized by a simple, rapid combustion synthesis process and evaluated as conversion anode materials in lithium half-cells. All showed markedly superior electrochemical performance compared to conventional spinel ferrites such as FeO and MgFeO, having capacities that could be maintained above 600 mAh g for 150 cycles, in most cases. X-ray absorption spectroscopy (XAS) results on pristine, discharged, and charged electrodes show that Fe, Co, Ni, and Cu are reduced to the elemental state during the first discharge (lithiation), while Mn is only slightly reduced. Upon recharge (delithiation), Fe is reoxidized to an average oxidation state of about 2.6+, while Co, Ni, and Cu are not reoxidized. The ability of Fe to be oxidized past 2+ accounts for the high capacities observed in these materials, while the presence of metallic elements after the initial lithiation provides an electronically conductive network that aids in charge transfer.
通过一种简单、快速的燃烧合成工艺合成了四种不同的包含5 - 6种不同金属的高熵尖晶石氧化物铁氧体（HESO）电极材料，并将其作为锂半电池中的转换阳极材料进行了评估。与传统的尖晶石铁氧体如FeO和MgFeO相比，所有材料均表现出显著优异的电化学性能，在大多数情况下，其容量在150次循环中可维持在600 mAh g以上。对原始、放电和充电电极的X射线吸收光谱（XAS）结果表明，在首次放电（锂化）过程中，Fe、Co、Ni和Cu被还原为元素态，而Mn仅略有还原。在充电（脱锂）时，Fe被重新氧化至平均氧化态约为2.6 +，而Co、Ni和Cu未被重新氧化。Fe能够被氧化超过2 +的能力解释了这些材料中观察到的高容量，而初始锂化后金属元素的存在提供了有助于电荷转移的电子导电网络。
