Druffel Daniel L, Pawlik Jacob T, Sundberg Jack D, McRae Lauren M, Lanetti Matthew G, Warren Scott C
Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States.
J Phys Chem Lett. 2020 Nov 5;11(21):9210-9214. doi: 10.1021/acs.jpclett.0c02266. Epub 2020 Oct 15.
It is widely assumed that the gain or loss of electrons in a material must be accompanied by its reduction or oxidation. Here, we report a system in which the insertion/deinsertion of an electron occurs without any reduction or oxidation. Using first-principles methods, we demonstrate this effect in the YCF-YC material system, where (e) indicates a lattice site containing a bare electron. We present a model in which YCF is in contact with a fluoride-containing electrolyte and the application of a positive voltage drives fluorination while a negative voltage reverses the process. We show that this chemistry does not change the oxidation states of the host lattice, causes no significant volume expansion, and occurs rapidly at room temperature. Finally, we demonstrate that this mechanism of ion insertion may enable a broad class of anion shuttle battery electrodes, some with gravimetric capacities nearly double those employed in intercalation-type Li-ion batteries.
人们普遍认为，材料中电子的得失必然伴随着其还原或氧化过程。在此，我们报道了一种系统，其中电子的插入/脱插过程发生时没有任何还原或氧化反应。使用第一性原理方法，我们在YCF-YC材料体系中证实了这种效应，其中(e)表示包含一个裸电子的晶格位点。我们提出了一个模型，其中YCF与含氟电解质接触，施加正电压会驱动氟化反应，而施加负电压则使该过程逆转。我们表明，这种化学反应不会改变主体晶格的氧化态，不会导致显著的体积膨胀，并且在室温下能快速发生。最后，我们证明这种离子插入机制可能使一类广泛的阴离子穿梭电池电极成为可能，其中一些电极的重量容量几乎是插层型锂离子电池所用电极的两倍。
