Impact of molecular modification on coal-tar-pitch-derived hard carbon for sodium-ion storage

doi:10.19799/j.cnki.2095-4239.2025.0364

Abstract

Abstract:

Developing suitable anode materials is essential for the commercialization of sodium-ion batteries. Coal tar pitch is an inexpensive soft carbon precursor with a high carbon yield; however, its low theoretical sodium storage capacity limits practical application. In this study, a molecular modification strategy is proposed, involving grafting various functional groups onto pitch molecules via electrophilic substitution reactions. This approach suppresses melting and rearrangement during carbonization, ultimately yielding hard carbon materials with enlarged interlayer spacing. The modified pitch is characterized by FT-IR and XPS to determine functional group composition. The morphology, microstructure, and pore structure of the resulting carbons are investigated using SEM, TEM, XRD, Raman spectroscopy, and N₂/CO₂ adsorption-desorption analyses. The effect of crosslinker content on the derived hard carbon structure is systematically examined by varying the crosslinking agent dosage. Sodium storage performance is evaluated through galvanostatic charge-discharge (GCD) tests, and the storage mechanism is further elucidated using cyclic voltammetry and the galvanostatic intermittent titration technique. The optimal performance is achieved at a 2:3 pitch/crosslinker ratio, delivering 291.4 mAh/g at 0.03 A/g (93% initial Coulombic efficiency) and 242.6 mAh/g after 300 cycles at 1 A/g with 95.6% retention.

Key words: coal tar pitch, hard carbon, anode, sodium-ion battery

CLC Number:

TQ 152

Shilong GUO, Jin SONG, Jiale GUO, Xiaoxiao WANG, Keying LIANG, Yilin WANG, Zonglin YI, Lijing XIE, Xianxian WEI. Impact of molecular modification on coal-tar-pitch-derived hard carbon for sodium-ion storage[J]. Energy Storage Science and Technology, 2025, 14(11): 4142-4151.

Figures/Tables 10

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Sample	Industrial analysis				Elemental analysis (mass fraction)/%					C/H
Sample	Softening point/℃	Coking value/%	Quinoline insoluble/%	Ash/%	C	H	O	N	S	C/H
CTP	144	63.5	0.18	0.02	91.96	5.36	2.80	1.15	0.08	1.43

Sample	d₀₀₂/Å	L_c /nm	L_a /nm	I_D/I_G	S_BETN₂/(m²/g)	S_BETCO₂/(m²/g)
CTP@SC	3.470	3.214	5.245	1.02	30.37	13.91
MP₂@HC	3.858	0.958	3.81	1.62	51.65	88.99
MP₃@HC	3.856	0.978	3.92	1.80	77.32	154.87
MP₄@HC	3.754	1.053	4.125	1.76	48.97	40.59

Sample	Charge specific capacity/(mAh/g)	Discharge specific capacity/(mAh/g)	ICE/%
CTP@SC	122.7	154.18	79.6
MP₂@HC	269.2	308.73	87.2
MP₃@HC	291.4	313.15	93.1
MP₄@HC	277.8	309.5	89.8