Flexible sodium-ion batteries using electrodes from Samanea saman tree leaf-derived carbon quantum dots decorated with SnO2 and NaVO3

Abstract

Carbonaceous materials with large interlayer spacing and disordered structure are considered suitable as electrodes in sodium-ion batteries so as to overcome the problem encountered in conventional electrodes. In this study, carbon quantum dots (CQDs) decorated with SnO2 and NaVO3 are used as electrodes in the fabrication of flexible Na-ion batteries. CQDs are prepared from dead leaves of the Samanea saman tree through alkaline-peroxide treatment and hydrothermal carbonization. As-prepared CQDs exhibit a quantum yield of 21.03% at an excitation wavelength of 360 nm. Various separators such as indium-doped tin oxide/polyoxyethylene tridecyl ether (ITO/PTE), rice paper (RP), silicone with three big holes (SIL BH), silicone with many small holes (SIL SH) and cellulose paper (CP) have been tried in flexible Na-ion batteries. SIL SH achieved higher specific capacitance (881 F g–1) than other separators due to the function of many small holes on the surface of the silicone. The SIL SH separator delivered higher discharge capacities of 141 and 114 mC g–1 at 1.5 and 2.5 V than SIL BH. The RP separator delivered specific discharge capacities of 1087 and 347 mC g–1 in the 1st and 50th cycles, respectively, at 1 V. The RP separator delivered a high initial specific discharge capacity of 698 mC g–1 at 2 V and maintained a good discharge capacity of 222 mC g–1 in the 50th cycle. As compared to RP, SIL SH delivered high specific discharge capacity of 4246 in 1st cycle at 2 V but maintained a capacity of 71 mC g–1 in the 50th cycle. This study reveals the scope of developing flexible Na-ion batteries with high capacity and cyclability using carbonaceous materials derived from the leaves of the S. saman tree. Carbon quantum dots (CQDs)-decorated with SnO2 and NaVO3 are used as electrodes in the fabrication of flexible Na-ion batteries. CQDs exhibit a quantum yield of 21% at the excitation wavelength of 360 nm. The electrochemical performances of fabricated batteries are investigated by cyclic voltammetry.

Nanocarbon in Sodium‐ion Batteries – A Review. Part 1: Zero‐dimensional Carbon Dots

“…However, their electrochemical performance in batteries are limited by large volumetric changes (~300 %) during the charging and discharging process, leading to rapid capacity loss, poor cyclic ability and low rate capability [ 101,102]. With the aim of overcoming the problems, SnO 2 is decorated with large interlayer spacing of nanostructured carbon materials such as carbon nanotubes, graphene, and carbon coated layers for volumetric expansion and to ensure structural integrity during sodiation and desodiation processes [6,[102][103][104][105].…”

“…Carbon quantum dots-decorated SnO 2 overcome the problems of pure SnO 2 such as large initial capacity loss and severe capacity fading, volume changes due to agglomeration of tin nanoparticle during alloying and de-alloying processes with metal ions affecting the pulverization and loss of electrical contact in the electrodes [6,105]. Thangaraj et al [6] developed for the first time Na-doped CQDs from the dead-leaf of a tree Samanea samam. They have regular arrangement of carbon atoms with large interlayer spacing of 0.371 nm.…”

“…13). The carbon quantum dots thus prepared are decorated with SnO 2 nanoparticle and used as anode in flexible Na-ion battery which delivered specific discharge capacities of 1087 and 347 mC g -1 in the 1st and 50th cycles at 1 V [6].…”

“…In line with the above, supercapacitors, fuel cells and batteries have come into being. Supercapacitors have high power density and cyclic stability while rechargeable batteries made from lead acid, Ni-Fe, Ni-Cd and Ni-metal hydride (Ni-MH), lithium and sodium-ion have a relatively large specific capacity which operates at high working voltages [4][5][6]. During the early stages, nickel-cadmium (Ni-Cd) and Ni-MH cells have been used in portable electronic devices.…”

“…The disposal of spent batteries is another major challenge in the context of deteriorating environment. Besides, the stock of lithium is dwindling fast and kindles geopolitics in certain regions -----such as South America, Australia, China and US where the reserve is relatively high [6,7].…”