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Copper Thiophosphate (Cu 3 PS 4 ) as Electrode for Sodium‐Ion Batteries with Ether Electrolyte
Author(s) -
Brehm Wolfgang,
Santhosha Aggunda L.,
Zhang Zhenggang,
Neumann Christof,
Turchanin Andrey,
Martin Andréa,
Pinicola,
Seyring Martin,
Rettenmayr Markus,
Buchheim Johannes R.,
Adelhelm Philipp
Publication year - 2020
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201910583
Subject(s) - thiophosphate , electrolyte , redox , materials science , inorganic chemistry , lithium (medication) , sodium , battery (electricity) , electrode , copper , chemistry , organic chemistry , medicine , power (physics) , physics , quantum mechanics , metallurgy , endocrinology
Lithium and sodium thiophosphates (and related compounds) have recently attracted attention because of their potential use as solid electrolytes in solid‐state batteries. These compounds, however, exhibit only limited stability in practice as they react with the electrodes. The decomposition products partially remain redox active hence leading to excess capacity. The redox activity of thiophosphates is explicitly used to act as electrode for sodium‐ion batteries. Copper thiophosphate (Cu 3 PS 4 ) is used as a model system. The storage behavior between 0.01 and 2.5 V versus Na + /Na is studied in half cells using different electrolytes with 1 m NaPF 6 in diglyme showing the best result. Cu 3 PS 4 shows highly reversible charge storage with capacities of about 580 mAh g −1 for more than 200 cycles @120 mA g −1 and about 450 mAh g −1 for 1400 cycles @1 A g −1 . The redox behavior is studied by operando X‐ray diffraction and X‐ray photoelectron spectroscopy. During initial sodiation, Cu 3 PS 4 undergoes a conversion reaction including the formation of Cu and Na 2 S. During cycling, the redox activity seems dominated by sulfur. Interestingly, the capacity of Cu 3 PS 4 for lithium storage is smaller, leading to about 170 mAh g −1 after 200 cycles. The results demonstrate that thiophosphates can lead to reversible charge storage over several hundred cycles without any notable capacity decay.