Organic Thiocarboxylate Electrodes for a Room‐Temperature Sodium‐Ion Battery Delivering an Ultrahigh Capacity

Abstract

Organic room-temperature sodium-ion battery electrodes with carboxylate and carbonyl groups have been widely studied. Herein, for the first time,wereport afamily of sodiumion battery electrodes obtained by replacing stepwise the oxygen atoms with sulfur atoms in the carboxylate groups of sodium terephthalate whichi mproves electron delocalization, electrical conductivity and sodium uptake capacity.T he versatile strategy based on molecular engineering greatly enhances the specific capacity of organic electrodes with the same carbon scaffold. By introducing two sulfur atoms to as ingle carboxylates caffold, the molecular solid reaches ar eversible capacity of 466 mAh g À1 at ac urrent density of 50 mA g À1 .When four sulfur atoms are introduced, the capacity increases to 567 mAh g À1 at ac urrent density of 50 mA g À1 , which is the highest capacity value reported for organic sodium-ion battery anodes until now.Organic battery electrodes are alternatives to traditional metal-oxide electrode materials due to their low costs, absence of heavy metals and easily tunable structures. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Generally,o rganic electrodes accommodate redox centers and alkali-metal ions by functional groups such as carboxylate, [16] carbonyl, [17] organodisulfide, [18] thioether [19] and nitroxyl radicals, [20] while the aromatic cores donate or accept electrons during the redox process. [19] Carboxylate groups are usually applied as lithium/sodium anodes which reversibly store/release Li + /Na + ions through at wo-electron process. [21,22] In the case of alithium-ion anode,far more than two Li + ions can be stored in the carboxylate molecule under deep discharge, [23,24] which leads to the high capacity of organic lithium anodes.H owever,f or sodium-ion battery cells,there is no evidence of super-sodiation. Thesodium ion is larger and less electronegative than the lithium ion.Even though the organic sodium-ion battery has al ower specific capacity than the lithium-ion battery,the sodium-ion battery is attractive because of the less rigid lattice compared with metal-oxide lattices,w hich can accommodate the large sodium ions so that the rate capability and cycle stability are advantageous. [21] As ac lassic organic sodium-ion battery anode,the sodium salt of terephthalate (PTA-Na, compound a in Figure 1) has ac apacity of 295 mAh g À1 at ac urrent density of 0.

Nitroaromatics as High‐Energy Organic Cathode Materials for Rechargeable Alkali‐Ion (Li+, Na+, and K+) Batteries

“…Prior to this work, the highest initial reversible capacity reported for organic electrode materials in room temperature SIBs was 567 mAh g −1 (energy density: 737 Wh kg −1 ) for sodium tetrathioterephthalate by eight-electron transfer reactions. [59] In addition, polydopamine was also reported to have a high capacity of 500 mAh g −1 (energy density: 500 Wh kg −1 ). [60] However, it should be noted that both only show sloping voltage profiles with no distinct voltage plateau and can only be used as organic anode materials for SIBs due to low operating voltages (<1.5 V).…”

A One‐Dimensional π–d Conjugated Coordination Polymer for Sodium Storage with Catalytic Activity in Negishi Coupling

“…Of particular note are the anode materials,because commercial anode materials for LIBs (graphite) deliver very low sodium storage.M any efforts have been made to explore novel anode materials for SIBs; [8][9][10][11][12] however,m ost of them either delivered low capacities or showed poor cycling life. Thea node materials with high capacity and cycleability, therefore,are highly desirable for SIBs.…”

A novel π-conjugated poly(biphenyl diimide) with full utilization of carbonyls as a highly stable organic electrode for Li-ion batteries

“…The capacity exceeding 100% may attribute to the contribution of carbon black. 46 The sloping charge-discharge voltage proles were attributed to the Li-ions insertion into polymers of different molecular weight and phase domains at different voltages.…”