Enhanced sodium storage property of copper nitrate hydrate by carbon nanotube

In this work, novel nano/micro structure nitrates are reported for sodium storage for the first time. By using a facile solution route, carbon black (CB) and carbon nanotube (CNT) are introduced to incorporate with copper nitrate hydrate (Cu(NO 3 ) 2 ·2.5H 2 O) to form Cu(NO 3 ) 2 ·2.5H 2 O/CB and Cu(NO 3 ) 2 ·2.5H 2 O/CNT composites for high capacity sodium storage, respectively. Morphological and structural investigations show that CB or CNT coating does not obviously change the particle size and phase composition of Cu(NO 3 ) 2 ·2.5H 2 O, while, the electrochemical performance of Cu(NO 3 ) 2 ·2.5H 2 O is significantly improved by introducing CB or CNT as a conductive network. Moreover, carbon matrix can also provide a buffer for suppressing particle pulverization during sodiation/desodiation process. Especially for CNT, it builds a three-dimensional conductive network for active particles. As a result, Cu(NO 3 ) 2 ·2.5H 2 O/CNT exhibits higher reversible specific capacity and better cycling stability than bare Cu(NO 3 ) 2 ·2.5H 2 O and Cu(NO 3 ) 2 ·2.5H 2 O/CB. After 30   cycles, Cu(NO 3 ) 2 ·2.5H 2 O/CNT can deliver a reversible charge capacity of 140.7   mAh   g −   1 at a current density of 50   mA   g −   1 . This result demonstrates that CNT reinforced Cu(NO 3 ) 2 ·2.5H 2 O composite could be a probable anode material for sodium-ion batteries. Besides, the probable sodium storage mechanism in Cu(NO 3 ) 2 ·2.5H 2 O is also proposed by using various ex-situ analytical methods.