Exploring the prospects of potassium vanadate as a negative electrode in an aqueous Al-ion gel battery with copper-Prussian blue analogue positive electrode for solar applications

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2025年1月20日

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Pappu Naskar,
Subarna Mandal,
Deblina Banerjee,
Arijit Dey,
Indranil Dinda,
Madhushri Maiti,
Sribas Mondal,
Anjan Banerjee

摘要

Aqueous Al-ion battery is minimally explored for large-scale stationary applications, namely, solar energy storage, but it has a great potential for industrialization because of low cost, high safety, and environmental sustainability. Herein, we develop a low-cost aqueous Al ion battery, whereas carbon nanotube–coated stainless steel (SS304), potassium vanadate (K_0.51V₂O₅/KVO), and copper-Prussian blue analogue (Na₂CuFe(CN)₆/Cu-PBA) are employed as respective current collector, negative and positive electrodes. To prevent anodic corrosion in low-cost SS304 substrate, the carbon coating is applied, which also expands the water-splitting window. Vanadate compounds have excellent prospects in metal ion batteries, because of accessible multiple valence states of vanadium and stable layered structure. Eventually, vanadates are rarely reported as positive materials, but not at all exploded as negative active materials in Al-ion electrochemistry. In this article, we have explored the prospects of KVO as a negative electrode in an aqueous Al-ion battery, while it delivers ~ 49 mAh g⁻¹ specific capacity at 100 mA g⁻¹ in 0.5 M Al₂(SO₄)₃. The KVO demonstrates high solid-state electronic conductivity at 29.76 × 10⁻⁴ S cm⁻¹ and Al³⁺ ion diffusion coefficient at 1.03 × 10⁻¹¹ cm² s⁻¹. Hence, good rate capability is observed, whereas 65% capacity retention is obtained by increasing the current from 100 to 500 mA g⁻¹. However, a 1.5-V Cu-PBA//KVO full cell is assembled in SiO₂Al₂(SO₄)₃ hydrogel electrolyte, and it delivers a specific capacity of 49 mAh g⁻¹ (@ 100 mA g⁻¹), an energy density of 49 Wh kg⁻¹ (@ 100 W kg⁻¹), a power density of 600 W kg⁻¹ (@ 42 Wh kg⁻¹), and excellent durability (20% capacity loss after 500 cycles @ 300 mA g⁻¹) within 0–1.5 V regime. This result is significantly better than those reported in the literature. Finally, a 4-V/5-mAh rated prototype Al-ion battery is fabricated that shows efficient solar energy storage applications.

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