Reversible High Capacity and Reaction Mechanism of Cr 2 (NCN) 3 Negative Electrodes for Li‐Ion Batteries

Jeethu Jiju Arayamparambil (1, 2) , Moulay Tahar Sougrati (3, 2, 1) , Jeethu Arayamparambil (1) , Kaixuan Chen (4) , Antonella Iadecola (5, 3) , Markus Mann (4) , Xianji Qiao (4) , Bernard Fraisse (1) , Richard Dronskowski (4, 6) , Lorenzo Stievano (1, 3, 2)

1 ICGM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier
2 ALISTORE-ERI - Advanced Lithium Energy Storage Systems - ALISTORE-ERI
3 RS2E - Réseau sur le stockage électrochimique de l'énergie
4 IAC RWTH - Institute of Inorganic Chemistry [Aachen]
5 SSOLEIL - Synchrotron SOLEIL
6 Shenzhen Polytechnic

A detailed study of the electrochemical reaction mechanism between lithium and the trivalent transition-metal carbodiimide Cr2(NCN)3, which shows excellent performance as a negative electrode material in Li-ion batteries, is conducted combining complementary operando analyses and state-of-the-art density functional theory (DFT) calculations. As predicted by DFT, and evidenced by operando X-ray diffraction and Cr K-edge absorption spectroscopy, a two-step reaction pathway involving two redox couples (Cr3þ/Cr2þ and Cr2þ/Cr0) and a concomitant formation of Cr metal nanoparticles is apparent, thus indicating that the conversion reaction of this carbodiimide upon lithiation occurs only after a preliminary intercalation step involving two Li per unit formula. This mechanism, evidenced for the first time in transition-metal carbodiimides, is likely behind its outstanding electrochemical performance as Cr2(NCN)3 can maintain more than 600 mAh g1 for 900 cycles at a high rate of 2 C.

Domaines: Matériaux

Jeethu Jiju Arayamparambil, Moulay Tahar Sougrati, Jeethu Arayamparambil, Kaixuan Chen, Antonella Iadecola, et al.. Reversible High Capacity and Reaction Mechanism of Cr 2 (NCN) 3 Negative Electrodes for Li‐Ion Batteries. Energy Technology, 2020, 8 (3), pp.1901260. ⟨10.1002/ente.201901260⟩. ⟨hal-02514522⟩