Abstract
Li 2S is a high-capacity cathode material for lithium metal-free rechargeable batteries. It has a theoretical capacity of 1166 mAh/g, which is nearly 1 order of magnitude higher than traditional metal oxides/phosphates cathodes. However, Li 2S is usually considered to be electrochemically inactive due to its high electronic resistivity and low lithium-ion diffusivity. In this paper, we discover that a large potential barrier (∼1 V) exists at the beginning of charging for Li 2S. By applying a higher voltage cutoff, this barrier can be overcome and Li 2S becomes active. Moreover, this barrier does not appear again in the following cycling. Subsequent cycling shows that the material behaves similar to common sulfur cathodes with high energy efficiency. The initial discharge capacity is greater than 800 mAh/g for even 10 μm Li 2S particles. Moreover, after 10 cycles, the capacity is stabilized around 500-550 mAh/g with a capacity decay rate of only ∼0.25% per cycle. The origin of the initial barrier is found to be the phase nucleation of polysulfides, but the amplitude of barrier is mainly due to two factors: (a) charge transfer directly between Li 2S and electrolyte without polysulfide and (b) lithium-ion diffusion in Li 2S. These results demonstrate a simple and scalable approach to utilizing Li 2S as the cathode material for rechargeable lithium-ion batteries with high specific energy. © 2012 American Chemical Society.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 15387-15394 |
| Number of pages | 8 |
| Journal | Journal of the American Chemical Society |
| Volume | 134 |
| Issue number | 37 |
| DOIs | |
| State | Published - Sep 10 2012 |
| Externally published | Yes |
Bibliographical note
KAUST Repository Item: Exported on 2020-10-01Acknowledged KAUST grant number(s): KUS-l1-001-12
Acknowledgements: A portion of this work was supported by the Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under contract DE-AC02-76SF0051 through the SLAC National Accelerator Laboratory, Laboratory Directed Research and Development funding, under contract DE-AC02-76SF00515 (J.N., M.F.T., Y.C.). Y.C. acknowledges support from a King Abdullah University of Science and Technology (KAUST) Investigator Award (No. KUS-l1-001-12). Y.Y. acknowledges financial support from the Stanford Graduate Fellowship (SGF). G.Z. acknowledges financial support from the Agency for Science, Technology and Research (A*STAR), Singapore. Portions of this research were carried out at the Stanford Synchrotron Radiation Lightsource, a national user facility operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.
