Oxygen Defects Engineering of VO₂·xH₂O Nanosheets via In Situ Polypyrrole Polymerization for Efficient Aqueous Zinc Ion Storage

Abstract

What has been a crucial demand is that designing mighty cathode materials for aqueous zinc−ion batteries (AZIBs), which are vigorous alternative devices for large−scale energy storage by means of their high safety and low cost. Herein, a facile strategy is designed that combines oxygen defect engineering with polymer coating in a synergistic action. As an example, the oxygen−deficient hydrate vanadium dioxide with polypyrrole coating (Od−HVO@PPy) is synthesized via a one‐step hydrothermal method in which introducing oxygen vacancy in HVO is simultaneously realized during the in situ polymerization. Such a desirable material adjusts the surface adsorption and internal diffusion of Zn2+ demonstrated by electrochemical characterization and theoretical calculation results. Moreover, it also utilizes conductive polymer coating to improve electrical conductivity and suppress cathode dissolution. Therefore, the Od−HVO@PPy electrode delivers a preferable reversible capacity (337 mAh g−1 at 0.2 A g−1) with an impressive energy density of 228 Wh kg−1 and stable long cycle life. This enlightened design opens up a new modus operandi toward superior cathode materials for advanced AZIBs.

Zincophilic Cu Sites Induce Dendrite‐Free Zn Anodes for Robust Alkaline/Neutral Aqueous Batteries

“…Aqueous rechargeable Zn-based batteries hold significant potential for storage of the intermittent renewable energy for their intrinsic advantages of Zn-based anode, including cost-effectiveness, abundant resources, good safety, environmental benignity, high theoretical capacity (820 mAh g −1 and 5851 mAh L −1 ), and low redox potential (−0.76 V versus the standard hydrogen electrode). [1][2][3][4][5] Nevertheless, the commercialization of these Zn-based batteries is still retarded by the inferior cyclic durability of Zn anodes in aqueous electrolytes during the charge/ discharge process. [6,7] Specifically, the uncontrollable dendrite growth evoked by the inhomogenous Zn nucleation during Zn plating/stripping process would puncture the separator and further give rise to internal short circuit.…”

ZnV2O4‐Textured Carbon Composite Contacting a ZIF‐8 MOF Layer for a High Performance Non‐Aqueous Zinc‐Ion Battery

“…Vanadium based oxides have been widely used as hosts in aqueous ZIBs due to their layered structures and wide inter-layer separations and some examples worthy of note are: Zn 0.3 V 2 O 5 • 1.5H 2 O, which delivered a capacity of 426 mAh g À 1 at 0.2 A g À 1 and exhibited a cycling stability with a capacity retention of 96 % over 20000 cycles at 10 A g À 1 , [15] porous Mg 0.34 V 2 O 5 • 0.84H 2 O nanobelts which produced a capacity of 353 mAh g À 1 at 100 mA g À 1 , with ~97 % capacity retention for 2000 cycles, [16] Na 2 V 6 O 16 • 3H 2 O nanorods that offered a specific energy of 90 Wh kg À 1 at a specific power of 15.8 kW kg À 1 , [17] a commercial V 2 O 5 cathode, which showed a reversible capacity of 470 mAh g À 1 at 0.2 A g À 1 and a long-term cyclability with 91 % capacity retention over 4000 cycles at 5 A g À 1 , [18] ZnVOH/ carbon cloth based flexible ZIB that showed a high discharge capacity of 184 mAh g À 1 at 10 A g À 1 after 170 cycles [19] and NaV 3 O 8 • 1.5H 2 O nanobelts, with a high reversible capacity of 380 mAh g À 1 and capacity retention of 82 % over 1000 cycles. [20] Most of the above described reports on ZIBs are based on aqueous electrolytes, [15][16][17][18][19][20][21] but i) their narrow electrochemical potential stability, limited by the decomposition potential of water at ~1.23 V, thereby restricting the operational voltage of the ZIB, ii) the competitive insertion of H + ions in an acidic aqueous medium along with Zn 2 + , and iii) the possible undesirable side reactions of water with cathode materials can have deleterious effects on the capacity and lifespan of ZIBs, thus rendering them to rather unsuitable for scale up or any real-world applications. These issues can be addressed by the use of non-aqueous electrolytes, but at the expense of Zn(II) storage capacity.…”

Kinetically Accelerated Lithium Storage in High‐Entropy (LiMgCoNiCuZn)O Enabled By Oxygen Vacancies

“…Thereinto, the capacity is composed of surface capacitive-controlled capacity and solid diffusion-controlled capacity. According to the empirical formula, the relationship between peak current (i) and scan rate (v) follows the power law: [16,42]…”