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Lithium chromium pyrophosphate as an insertion material for Li‐ion batteries
Author(s) -
Reichardt Martin,
Sallard Sébastien,
Novák Petr,
Villevieille Claire
Publication year - 2015
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s2052520615017539
Subject(s) - thermogravimetric analysis , lithium (medication) , scanning electron microscope , electrochemistry , chromium , pyrophosphate , materials science , nuclear chemistry , redox , conductivity , powder diffraction , oxidation state , ion , analytical chemistry (journal) , inorganic chemistry , chemistry , crystallography , electrode , metallurgy , metal , medicine , organic chemistry , composite material , enzyme , endocrinology , biochemistry , chromatography
Lithium chromium pyrophosphate (LiCrP 2 O 7 ) and carbon‐coated LiCrP 2 O 7 (LiCrP 2 O 7 /C) were synthesized by solid‐state and sol–gel routes, respectively. The materials were characterized by X‐ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and conductivity measurements. LiCrP 2 O 7 powder has a conductivity of ∼ 10 −8 S cm −1 , ∼ 10 4 times smaller than LiCrP 2 O 7 /C (∼ 10 −4 S cm −1 ). LiCrP 2 O 7 /C is electrochemically active, mainly between 1.8 and 2.2 V versus Li + /Li (Cr 3+ /Cr 2+ redox couple), whereas LiCrP 2 O 7 has limited electrochemical activity. LiCrP 2 O 7 /C delivers a reversible specific charge up to ∼ 105 mAh g −1 after 100 cycles, close to the theoretical limit of 115 mAh g −1 . Operando XRD experiments show slight peak shifts between 2.2 and 4.8 V versus Li + /Li, and a reversible amorphization between 1.8 and 2.2 V versus Li + /Li, suggesting an insertion reaction mechanism.