Enhanced electrochemical performance of sodium lithium titanate by coating various carbons

• CB, GN and CNT are used as conductive bridges between Na2Li2Ti6O14 particles.
• CNT fabricates a better three-dimensional network than CB and GN.
• Na2Li2Ti6O14/CNT reveals a reversible capacity of 98.9 mAh g−1 at 400 mA g−1.

To improve the electrochemical performance of Na2Li2Ti6O14, carbon black (CB), graphene (GN) and carbon nanotube (CNT) are introduced to fabricate high conductive Na2Li2Ti6O14/CB, Na2Li2Ti6O14/GN, Na2Li2Ti6O14/CNT and Na2Li2Ti6O14/CB/GN/CNT by a solid state method. It can be found that only CNT forms a complete three-dimensional conductive network which embeds the randomly distributed Na2Li2Ti6O14 particles, leading to an improvement of electronic conductivity. The results of cyclic voltammetry, electrochemical impedance spectroscopy and charge–discharge tests reveal that Na2Li2Ti6O14/CNT obtains the lowest redox polarization and the highest peak current among all the five samples. As a result, Na2Li2Ti6O14/CNT shows the best cycling and rate performances among all the five samples. It reveals a charge capacity of 111.4 mAh g−1 at 100 mA g−1, 110 mAh g−1 at 200 mA g−1, 103.9 mAh g−1 at 300 mA g−1 and 98.9 mAh g−1 at 400 mA g−1. For comparison, bare Na2Li2Ti6O14 only displays a charge capacity of 89.9 mAh g−1 at 100 mA g−1, 79.7 mAh g−1 at 200 mA g−1, 73.7 mAh g−1 at 300 mA g−1 and 69.4 mAh g−1 at 400 mA g−1. It indicates that the introduction of CNT is more effective to improve the performance of Na2Li2Ti6O14 than CB, GN and CB/GN/CNT.

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