Feng Chen,Yuzhu Qian,Yaoyong Dong,Lijuan Chen,Ting Song,Yong Pei,Xianyou Wang,Xiongwei Wu,Bei Long
The rich valence states (−2 to +6) make elemental Te become a high-capacity electrode in aqueous batteries. The conversion process (Te to TeO 2 ) generates soluble Te 4+ species in aqueous electrolyte. The suppression of conversion process enables a long-term Te electrode at the cost of a partial storage capacity. Herein, a polyethylene glycol additive is introduced to regulate the electrolyte environment. The low H 2 O activity hinders Te 4+ species formation and therefore leads to the insertion-type Te electrode. The reshaped NH 4 + solvation structure facilitates the fast H 2 O removal and firm PEG adsorption on the electrode surface, also improving water-induced side reactions. This, coupled with the introduction of carbon host, contributes to a high-stability Te electrode. Theoretical and experiment studies reveal the reshaped NH 4 + solvation structure/hydrogen-bond network, the strong adsorption capability of B-doped carbon, and the inhibited Te dissolution. Additionally, a series of in/ex-situ characterizations prove the intercalation-type mechanism and the enhanced cycling stability. As a result, this elaborate electrode delivers a high reversible capacities of 376 mA h g −1 at 0.05 A g −1 and a long-term cycling stability with 73.8 % capacity retention at 5 A g −1 after 4500 cycles. This work provides a reference for the storage mechanism regulation in aqueous battery.
Pre-intercalation has emerged as a highly effective strategy to enhance structural integrity and ion transport kinetics in cathodes for aqueous Zn-ion batteries. Here, we report a zinc-ion pre-intercalated hydrate vanadium oxide cathode, in which the initial insertion of Zn 2+ induces a significant expansion of the interplanar spacing, followed by contraction at higher Zn 2+ concentrations owing to strong electrostatic interactions with the V O framework. Such competing expansion and contraction of interplanar spacing enhances the overall electrochemical properties. In addition, the pre-intercalated Zn 2+ facilitates the in situ formation of a Zn 3 (OH) 2 V 2 O 7 ·2H 2 O cathode-electrolyte interphase (CEI) layer, which not only suppresses vanadium dissolution but also regulates the desolvation of hydrated Zn 2+ , thus further enhancing the structural integrity and interfacial kinetics. Benefiting from these merits, the Zn 2+ pre-intercalated hydrate vanadium pentoxide (denoted as 2Zn-VOH) cathode delivers a high capacity of 395 mA h g −1 at 0.1 A g −1 , exhibits excellent cycling stability at both low and high current densities, and retains outstanding performance under low-temperature conditions (295 mAh g −1 at 0.1 A g −1 and − 10 °C, with 83.8 % capacity retention after 1000 cycles at 0.2 A g −1 ).
Pt single-atom materials possess an ideal atom economy but suffer from limited intrinsic activity and side reaction of producing H2O2 in catalyzing the oxygen reduction reaction (ORR); platinum alloys have higher intrinsic activity but weak stability. Here, we demonstrate that anchoring platinum alloys on single-atom Pt-decorated carbon (Pt-SAC) surmounts their inherent deficiencies, thereby enabling a complete four-electron ORR pathway catalysis with high efficiency and durability. Pt3Co@Pt-SAC demonstrates an exceptional mass and specific activities 1 order of magnitude higher than those of commercial Pt/C. They are durable throughout 50000 cycles, showing only a 10 mV decay in half-wave potential. An in situ Raman analysis and theoretical calculations reveal that Pt3Co core nanocrystals modulate electron structures of the adjacent Pt single atoms to facilitate the intermediate absorption for fast kinetics. The superior durability is attributed to the shielding effect of the Pt-SAC coating, which significantly mitigates the dissolution of Pt3Co cores. The hybridizing strategy might promote the development of highly active and durable ORR catalysts.
危险品化学品经营许可证（带存储）