Zinc Batteries: A Sustainable Energy Storage Solution

The increasing global demand for energy and the potential environmental impact of increased energy consumption require greener, safer, and more cost-efficient energy storage technologies. Zinc-ion batteries (ZIBs) have recently attracted attention due to their safety, environmental friendliness, and lower cost, compared to LIBs. They use aqueous electrolytes, which give them an advantage over multivalent ion batteries (e.g., Mg2+, Ca2+, Al3+) that require more complex electrolytes.

Overview

• Oldest type of primary battery, commonly known as the Leclanché Cell.

• Widely used due to low cost and reliability.

Historical Background

• Invented by Georges Leclanché in 1866.

• First battery to use a single low-corrosive fluid electrolyte with a solid cathode, resulting in low self-discharge.

Basic Components and Variants

• Anode: Solid zinc.

• Electrolyte: Ammonium chloride paste (standard) or zinc chloride for heavy-duty use.

• Cathode: Manganese dioxide mixed with carbon to improve conductivity and moisture retention.

• Variants: Alkaline cells use potassium hydroxide as the electrolyte.

Key Characteristics

• Voltage: 1.5–1.75 V.

• Discharge: Sensitive to external factors, better with intermittent use.

• Service Life: ~110 minutes (continuous use).

• Shelf Life: 1–2 years at room temperature.

Electrochemical Principles

zinc-ion batteries (ZIBs), consist of a zinc metal anode, a zinc-containing electrolyte, and a cathode for hosting Zn ions. The operation of zinc batteries is based on redox reactions. The general anodic reaction for zinc is:

Zn (s)→Zn2+ + 2e−

Major features of Zn-ion batteries:

(1) the diversity of potential electrolytes, including aqueous and non-aqueous electrolytes

(2) the higher redox potential of zinc (-0.763 V vs. a standard hydrogen electrode [SHE]), which can allows the battery to work in aqueous electrolytes which is difficult to be realized for other mobile ion batteries

(3) the improved safety and reduced toxicity of ZIBs

(4) the reversibility of Zn plating/stripping, where the near-neutral or slightly acidic electrolyte (e.g., pH = 3.6–6.0) can avoid the formation of zinc dendrites and ZnO byproducts, unlike the case of an alkaline Zn battery (e.g., Zn + 4OH− ↔ Zn(OH)42- + 2e− ↔ ZnO + 2OH− + H2O + 2e−).Therefore, a long cycle life can be achieved.

(5) a higher volumetric energy density (i.e., 5855 mA h cm-3 compared to 2061 mA h cm-3 for LIBs) can be achieved due to the high density of Zn and the fact that two electrons are involved in the electrochemical reactions. Making ZIBs that are small in size is essential for deployment in miniaturized devices such as epidermal, implantable, and wearable sensors.

All the above features mean that there is great potential for the commercialization of Zn-ion batteries.

Zinc-Carbon Batteries (Leclanché Cell):

• Chemistry: Zinc anode, manganese dioxide (MnO₂) cathode, and an acidic or neutral electrolyte.

• Voltage: Typically 1.5 V.

• Applications: Flashlights, remote controls, and low-drain devices.

• Advantages: Low cost and simplicity.

• Challenges: Limited energy density and leakage risk due to acidic electrolytes.

Alkaline Zinc Batteries:

• Chemistry: Zinc anode, MnO₂ cathode, and potassium hydroxide (KOH) as the electrolyte.

• Voltage: 1.5 V nominal.

• Applications: High-drain devices like cameras and toys.

• Advantages: Higher energy density and better shelf life compared to zinc-carbon.

• Challenges: Limited recyclability and corrosion issues over time.

Zinc-Air Batteries:

• Chemistry: Zinc anode, oxygen from air as the cathode, and an aqueous or gelled electrolyte.

• Voltage: 1.2–1.4 V.

• Applications: Hearing aids, off-grid energy storage, and electric vehicles.

• Advantages: High energy density due to the use of ambient oxygen as the active cathode material.

• Challenges: Susceptibility to drying out, carbonation of the electrolyte, and reduced efficiency over time.

Rechargeable Zinc-Based Batteries:

• Includes zinc-ion, zinc-nickel, and zinc-manganese batteries.

• Employ aqueous or hybrid electrolytes and advanced cathode materials to enable rechargeability.

Key Advantages of Zinc

• Abundance of Zinc: Zinc is the fourth most widely used metal and is abundantly available, ensuring supply stability.

• Safety: Aqueous zinc batteries mitigate risks associated with thermal runaway, common in lithium-ion systems.

• Cost-Effectiveness: Zinc is cheaper to mine and process compared to lithium and cobalt.

• Recyclability: Zinc batteries are easier to recycle, contributing to circular economy practices.

Challenges and Future Directions

Despite their potential, zinc batteries face several challenges:

1. Dendrite Formation

Zinc anodes are prone to dendrite growth, leading to short circuits and reduced efficiency.

2. Energy Density Limitations

While safer, aqueous zinc batteries generally have lower energy densities compared to lithium-ion systems.

3. Durability

Prolonging the lifespan of zinc batteries under various operational conditions remains a key research focus.

Advancements in Zinc Battery Technology

1. Enerpoly’s Zinc-Ion Battery Megafactory:

• Enerpoly inaugurated the world’s first zinc-ion battery megafactory in Stockholm, Sweden.

• The 6,500m² facility will begin production in 2025, scaling to 100 megawatt-hours annually by 2026.

• Zinc-ion batteries, known for safety, cost-efficiency, and long life, are ideal for grid stabilization, renewable energy storage, and portable devices.

• Enerpoly introduced advanced dry electrode technology to reduce costs, waste, and energy consumption, boosting sustainability.

2. Hindustan Zinc Partnership with AE sir Technologies:

• Hindustan Zinc partnered with US-based AEsir Technologies to supply zinc for next-generation zinc-based batteries.

• Zinc batteries offer high power, minimal maintenance, recyclability, and a lifespan of up to 20 years.

• Their greenhouse gas footprint is six times lower than other storage technologies, making them suitable for industrial energy storage.

• This announcement drove Hindustan Zinc’s stock price up by nearly 6%, reflecting market optimism.

3. Advances in Rechargeable Aqueous Zinc-Iodine Batteries:

• Researchers developed fluorinated block copolymers as solid electrolytes for ZnI₂ batteries.

• The technology forms a fluoride-rich SEI layer, preventing dendrite growth and extending battery life.

• Symmetric cells demonstrated 5,000 hours of stability, and ZnI₂ batteries achieved 7,000 cycles with 72.2% capacity retention.

• High-rate performance delivers a reversible capacity of 79.8 mAh g⁻¹ at 20 C, showcasing commercial potential.

• Promises reliable energy storage solutions, including flexible and wearable zinc-based batteries.

These advancements highlight zinc batteries' growing role in sustainable and efficient energy storage systems, driving innovation across industrial, portable, and grid-scale applications.

Conclusion

Zinc batteries hold immense potential to revolutionize the energy storage landscape. Their cost-effectiveness, safety, and environmental benefits make them highly relevant in today’s pursuit of sustainable energy solutions. Continued research and innovation are crucial to overcoming current limitations and unlocking their full potential, ensuring a greener and more energy-secure future.

References:

Hindustan Zinc Joins Hands With US-Based Firm To Develop Zinc Batteries, Shares Rocket 6% - Benzinga

Beyond lithium: New solid state ZnI₂ battery design opens doors for sustainable energy storage

Enerpoly opens world's first zinc-ion battery mega-factory in Sweden

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