Pyrolysis temperature dependence of sodium storage mechanism in non-graphitizing carbons

Hélène Tonnoir (1) , Da Huo (1) , Carine Davoisne (1, 2) , Alain Celzard (3, 4) , Vanessa Fierro (3) , Damien Saurel (5) , Mimoun El Marssi (6) , Manal Benyoussef (6) , Philippe Meunier (7) , Raphaël Janot (1)

1 LRCS - Laboratoire réactivité et chimie des solides - UMR CNRS 7314
2 RS2E - Réseau sur le stockage électrochimique de l'énergie
3 IJL - Institut Jean Lamour
4 IUF - Institut universitaire de France
5 CIC ENERGIGUNE - Parque Tecnol Alava
6 LPMC - Laboratoire de Physique de la Matière Condensée - UR UPJV 2081
7 MERSEN France Gennevilliers S.A.S

Hard carbons are the most investigated materials as negative electrode for Na-ion batteries, although the exact mechanism of sodium storage remains under debate. This work is focused on the study of the sodiation mechanism of non-graphitizing carbons (NGC) prepared in a wide range of pyrolysis temperatures (1000 °C–2500 °C), thus covering the whole range from hard carbons (HC) to glassy carbons (GC). Structural and textural characterizations show that increasing the pyrolysis temperature leads to NGCs with a more ordered structure, containing fewer heteroatoms and structural defects, and particularly leads to a developed closed microporosity. In this work, in situ Raman spectroscopy at different excitation wavelengths is used to clarify the mechanism of electrochemical sodiation: it is revealed that the intercalation of Na+ between the graphene layers occurs mainly during the sloping part of the galvanostatic profile, whereas the plateau at low voltage (below 0.1 V vs. Na+/Na) can be associated with the filling of micropores with sodium.

Mots clés: Hard carbon; Sodium-ion battery; SAXS; Porosity; In situ Raman spectroscopy

Domaines: Matériaux

Hélène Tonnoir, Da Huo, Carine Davoisne, Alain Celzard, Vanessa Fierro, et al.. Pyrolysis temperature dependence of sodium storage mechanism in non-graphitizing carbons. Carbon, 2023, 208, pp.216-226. ⟨10.1016/j.carbon.2023.03.055⟩. ⟨hal-04082075⟩