Electrochemical Generation of Hydrated Zinc Vanadium Oxide with Boosted Intercalation Pseudocapacitive Storage for a High-Rate Flexible Zinc-Ion Battery

Abstract

With the surging development of flexible wearable and stretchable electronic devices, flexible energy-storage devices with excellent electrochemical properties are in great demand. Herein, a flexible Zn-ion battery comprised by hydrated zinc vanadium oxide/carbon cloth (ZnVOH/CC) as the cathode is developed, and it shows a high energy density, superior lifespan, and good safety. ZnVOH/CC is obtained by the in situ transformation of hydrated vanadium oxide/carbon cloth (VOH/CC) by an electrochemical method, and the intercalation pseudocapacitive reaction mechanism is discovered for ZnVOH/CC. The co-insertion/deinsertion of H+/Zn2+ is observed; the H+ insertion dominates in the initial discharge stage and the high-rate electrochemical process, while Zn2+ insertion dominates the following discharge stage and the low-rate electrochemical procedure. An ultrastable reversible capacity of 135 mAh g–1 at 20 A g–1 is obtained after 5000 cycles without capacity fading. Moreover, the as-assembled flexible zinc-ion battery can operate normally under rolled, folded, and punched conditions with superior safety. It is capable to deliver a high discharge capacity of 184 mAh g–1 at 10 A g–1 after 170 cycles. This work paves a new way for designing low-cost, safe, and quick-charging energy-storage devices for flexible electronics.

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 −1 at 0.2 A g −1 and exhibited a cycling stability with a capacity retention of 96 % over 20000 cycles at 10 A g −1 , [15] porous Mg 0.34 V 2 O 5 ⋅ 0.84H 2 O nanobelts which produced a capacity of 353 mAh g −1 at 100 mA g −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 −1 at a specific power of 15.8 kW kg −1 , [17] a commercial V 2 O 5 cathode, which showed a reversible capacity of 470 mAh g −1 at 0.2 A g −1 and a long‐term cyclability with 91 % capacity retention over 4000 cycles at 5 A g −1 , [18] ZnVOH/carbon cloth based flexible ZIB that showed a high discharge capacity of 184 mAh g −1 at 10 A g −1 after 170 cycles [19] and NaV 3 O 8 ⋅ 1.5H 2 O nanobelts, with a high reversible capacity of 380 mAh g −1 and capacity retention of 82 % over 1000 cycles [20] …”

“…Most of the above described reports on ZIBs are based on aqueous electrolytes, [15–21] 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.…”

“…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.…”

Understanding Zn‐Ion Insertion Chemistry through Nonaqueous Electrochemical Investigation of 2H‐NbSe2

“…[ 17 ] Also, a recent report experimentally demonstrates that with a hydrated VO 2 host, proton insertion dominates at high‐rate operation. [ 41 ] Moreover, repeated Zn‐ion insertion at slower rates leads to severe host material degradation due to the strong electrostatic interaction between Zn ions and the host and good cycle life is achieved at high rates due to reversible and facile insertion of protons that weakly interacts with the host. [ 41 ] This illustrates that hosts for MV‐ion insertion should be designed—in addition to the nanoscale particle sizes—to achieve MV‐ion migration barrier comparable or lower than ≈ 650 meV (i.e., weaker electrostatic host‐guest interaction) not only for reasonable solid‐state diffusion but also for the reversibility of the host material.…”

Binder-free three-dimensional interconnected CuV2O5·nH2O nests as cathodes for high-loading aqueous zinc-ion batteries

“…ZIBs with low mass load cannot be used for large-scale industrial energy storage applications and cannot achieve their excellent performance. [12][13][14] Therefore, it is of great significance to prepare ZIBs with high load and excellent performance.…”