51
4. The study of more chalcogenide electrodes with less electronegative elements
can be advantageous than highly electronegative oxygen-containing transitionmetal oxides and improve the sluggish Zn
2+
-ion diffusion kinetics and enhance
the performance parameters of ZIBs. Different strategies to developing specially
designed or hierarchical structured nanocomposites will be made to effectively
suppress cathode dissolution. Specifically, in relation to non-aqueous ZIBs,
being only just 1 year since its introduction, there will be a stiff race towards
achieving complete advancement.
5. The feasibility of widening the operating potential window (> 1.5 V) for ZIBs
can be realized by electrolyte optimization. For example, the effect of various
electrolyte parameters including salts, additives and their concentrations, pH and
their influence on the electrochemical reaction needs to be unraveled via on-time
monitoring of these factors.
6. One of the immediate challenges that should be addressed for the anodes is the
inhibition of dendrite formation. The dendrite factor becomes significant when
fabricating large-scale ZIBs beyond lab-scale limitations. This could be achieved
by suppressing the hydrogen evolution reaction during electrochemical reaction.
Surface coating of polymers or protective layers like an alternative SEI layer in
situ formation on the anode by using appropriate additive inclusions in the electrolyte can be helpful to prevent dendrite formation [111]. Another method to
evade dendrites is the use of solid/gel electrolytes with high mechanical and
ductile properties. This can also contribute to high zinc storage capacities and
performances [112].
7. From the long-term economic viewpoint, it is crucial for a new emerging energy
economy to be centered on cheap, green, and sustainable battery systems. The
low-cost and environmentally friendly features make manganese-based electrodes attractive for use in ZIBs. But the case is not true for vanadium as it is
faced with environmental issues. In economic terms, the recent years have seen
a significant fluctuation in the raw material costs. Specially, the cheapest raw
material of vanadium, V 2 O 5 was priced the lowest in 2016 (~ USD2/lb) before
shooting up to almost 17 times by late 2018 (~ 33.2 USD/lb). Currently, vanadium price is trending at 6.32 USD/lb., which is still three times higher than the
lowest cost. This uncertainty has become a matter of concern for the use of
vanadium-based materials, in general, for rechargeable batteries including ZIBs.
Therefore, it is immediately essential to develop efficiently reliable and ecofriendly methods for large-scale economical production of V 2 O 5 [113].
8. As the world of portable electronics is upgrading to next-generation technologies using wearable and flexible rollup displays and power devices, there will be
a significant effort to develop wearable or flexible aqueous ZIBs. From the engineering point of view, many more new strategies to design the ZIB in various
shapes and types will be pursued. More importantly, major stress will be given
to incorporate environmentally safe components and follow low-cost approaches
to realize stable, safe and economical grid-scale energy storage applications.
Recent Developments of Zinc-Ion Batteries
4. The study of more chalcogenide electrodes with less electronegative elements
can be advantageous than highly electronegative oxygen-containing transitionmetal oxides and improve the sluggish Zn
2+
-ion diffusion kinetics and enhance
the performance parameters of ZIBs. Different strategies to developing specially
designed or hierarchical structured nanocomposites will be made to effectively
suppress cathode dissolution. Specifically, in relation to non-aqueous ZIBs,
being only just 1 year since its introduction, there will be a stiff race towards
achieving complete advancement.
5. The feasibility of widening the operating potential window (> 1.5 V) for ZIBs
can be realized by electrolyte optimization. For example, the effect of various
electrolyte parameters including salts, additives and their concentrations, pH and
their influence on the electrochemical reaction needs to be unraveled via on-time
monitoring of these factors.
6. One of the immediate challenges that should be addressed for the anodes is the
inhibition of dendrite formation. The dendrite factor becomes significant when
fabricating large-scale ZIBs beyond lab-scale limitations. This could be achieved
by suppressing the hydrogen evolution reaction during electrochemical reaction.
Surface coating of polymers or protective layers like an alternative SEI layer in
situ formation on the anode by using appropriate additive inclusions in the electrolyte can be helpful to prevent dendrite formation [111]. Another method to
evade dendrites is the use of solid/gel electrolytes with high mechanical and
ductile properties. This can also contribute to high zinc storage capacities and
performances [112].
7. From the long-term economic viewpoint, it is crucial for a new emerging energy
economy to be centered on cheap, green, and sustainable battery systems. The
low-cost and environmentally friendly features make manganese-based electrodes attractive for use in ZIBs. But the case is not true for vanadium as it is
faced with environmental issues. In economic terms, the recent years have seen
a significant fluctuation in the raw material costs. Specially, the cheapest raw
material of vanadium, V 2 O 5 was priced the lowest in 2016 (~ USD2/lb) before
shooting up to almost 17 times by late 2018 (~ 33.2 USD/lb). Currently, vanadium price is trending at 6.32 USD/lb., which is still three times higher than the
lowest cost. This uncertainty has become a matter of concern for the use of
vanadium-based materials, in general, for rechargeable batteries including ZIBs.
Therefore, it is immediately essential to develop efficiently reliable and ecofriendly methods for large-scale economical production of V 2 O 5 [113].
8. As the world of portable electronics is upgrading to next-generation technologies using wearable and flexible rollup displays and power devices, there will be
a significant effort to develop wearable or flexible aqueous ZIBs. From the engineering point of view, many more new strategies to design the ZIB in various
shapes and types will be pursued. More importantly, major stress will be given
to incorporate environmentally safe components and follow low-cost approaches
to realize stable, safe and economical grid-scale energy storage applications.
Recent Developments of Zinc-Ion Batteries