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Long-term stable, high-capacity anode material for sodium-ion batteries: Taking a closer look at CrPS4 from an electrochemical and mechanistic point of view

DOI: 10.1021/acsami.1c14980 DOI Help

Authors: Jonas Van Dinter (Kiel University) , Sylvio Indris (Karlsruhe Institute of Technology) , Alexander Bitter (Kiel University) , David Grantz (Kiel University) , Giannantonio Cibin (Diamond Light Source) , Martin Etter (Deutsches Elektronen-Synchrotron (DESY)) , Wolfgang Bensch (Kiel University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acs Applied Materials & Interfaces

State: Published (Approved)
Published: November 2021
Diamond Proposal Number(s): 20060

Abstract: Electrochemical performance of the layered compound CrPS4 for the usage as anode material in sodium-ion batteries (SIBs) was examined and exceptional reversible long-term capacity and capacity retention were found. After 300 cycles, an extraordinary reversible capacity of 687 mAh g–1 at a current rate of 1 A g–1 was achieved, while rate capability tests showed an excellent capacity retention of 100%. Detailed evaluation of the data evidence a change of the electrochemical reaction upon cycling leading to the striking long-term performance. Further investigations targeted the reaction mechanism of the first cycle by applying complementary techniques, i.e., powder X-ray diffraction (XRD), pair distribution function (PDF) analysis, X-ray absorption spectroscopy (XAS), and 23Na/31P magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. The results indicated an unexpectedly complex reaction pathway including formation of several intercalation compounds, depending on the amount of Na inserted at the early discharge states and subsequent conversion to Na2S and strongly disordered metallic Cr at the completely discharged state. While XAS measurements suggest no further presence of intermediates after formation of Na intercalation compounds, several different phases are detected via MAS NMR upon continued discharging. Especially the data obtained from the MAS NMR investigations therefore point toward a very complex reaction pathway. Furthermore, solid electrolyte interphase (SEI) formation, resulting in the presence of NaF, was observed. After recharging the anode material, no structural long-range order occurred, but short-range order indeed resembled the local environment of the starting material, to a certain extent.

Journal Keywords: sodium-ion battery; anode material; CrPS4; sodium intercalation; X-ray scattering; pair distribution function; X-ray absorption

Diamond Keywords: Batteries; Sodium-ion

Subject Areas: Chemistry, Materials, Energy

Instruments: B18-Core EXAFS

Other Facilities: P02.1 at PETRA III

Added On: 15/11/2021 10:14

Discipline Tags:

Physical Chemistry Energy Energy Storage Materials Science Energy Materials Chemistry

Technical Tags:

Spectroscopy X-ray Absorption Spectroscopy (XAS)