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Use of Graphite as a Highly Reversible Electrode with Superior Cycle Life for Sodium-Ion Batteries by Making Use of Co-Intercalation Phenomena


  • We acknowledge support within the LOEWE program of excellence of the Federal State of Hessen (project initiative STORE-E). We thank Jürgen Janek, Siegfried Schindler, and Martin Winter for valuable discussions and Imerys (Bodio, Switzerland) for providing graphite materials.


Although being the standard anode material in lithium-ion batteries (LIBs), graphite so far is considered to fail application in sodium-ion batteries (NIBs) because the Na-C system lacks suitable binary intercalation compounds. Here we show that this limitation can be circumvented by using co-intercalation phenomena in a diglyme-based electrolyte. The resulting compound is a stage-I ternary intercalation compound with an estimated stoichiometry of Na(diglyme)2C20. Highlights of the electrode reaction are its high energy efficiency, the small irreversible loss during the first cycle, and a superior cycle life with capacities close to 100 mAh g−1 for 1000 cycles and coulomb efficiencies >99.87 %. A one-to-one comparison with the analogue lithium-based cell shows that the sodium-based system performs better and also withstands higher currents.

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