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Regulating Interfacial Na-Ion Flux via Artificial Layers with Fast Ionic Conductivity for Stable and High-Rate Na Metal Batteries
journal contribution
posted on 2019-07-29, 20:13 authored by Ke Lu, Siyuan Gao, Guosheng Li, Jacob Kaelin, Zhengcheng Zhang, Yingwen ChengMetallic
Na electrodes are promising anodes for low-cost and high-energy
density batteries due to their natural abundance and high specific
capacity. Unfortunately, they are extremely reactive and spontaneously
form unstable solid-electrolyte interphases, which lead to critical
challenges including growth of dendritic/mossy Na structures and fast
degradation. We report here the design of artificial interphase films
that have intrinsic high Na+-ion conductivity, which enable
protected Na electrodes with simultaneously improved surface stability
and redox kinetics. They were prepared from Mo6S8 films, which transform to NaxMo6S8 (x ≈ 16) through an
in-situ sodiation process when pressed onto Na metal. The protected
Na electrodes were stable in dry air for days and exhibited 2.5 times
higher exchange current density compared with pristine Na electrodes.
They enabled symmetric batteries with stable cycling for 1200 h at
0.5 mA cm–2 and fast Na metal batteries with substantially
improved high-rate performance and robust durability for 1000 cycles.