When we talk about battery technology, lithium-ion batteries often take center stage. However, in the battery family, there is a low-key yet highly promising member — the zinc-air battery. It not only encapsulates core reactants like traditional batteries but also "breathes" air to obtain energy like fuel cells. With its unique working mode, it shines in specific fields and is even regarded as an important alternative for future energy storage and new energy transportation.
I. What is a Zinc-Air Battery? Decoding Its Core Principle
A zinc-air battery, also known as a zinc-oxygen battery, is a type of metal-air battery that uses metallic zinc as the anode and oxygen from the air as the cathode active material. Its uniqueness lies in its "semi-storage and semi-extraction" energy mode: zinc at the anode is encapsulated inside the battery, like stored "fuel"; the cathode, on the other hand, does not need to store active materials. Instead, it captures oxygen from the air through a special structure to participate in reactions, theoretically having an infinite cathode capacity.
Its working process is essentially an exquisite electrochemical reaction. Mediated by an alkaline electrolyte (commonly potassium hydroxide solution), zinc at the anode loses electrons and is oxidized to form zinc oxide and water; oxygen at the cathode, under the action of catalysts (mostly activated carbon, manganese oxides, etc.), combines with electrons and water to generate hydroxide ions. These ions then migrate to the anode to continue participating in reactions. The overall reaction formula of the entire process is concise and efficient: 2Zn + O₂ → 2ZnO. The electrical energy released during the reaction can power devices, with a single battery output voltage of approximately 1.35-1.4V.
It is worth mentioning that the charging method of zinc-air batteries differs from that of traditional batteries. Early products were mostly primary batteries, which could be reused by replacing the zinc electrode and electrolyte after being depleted of power; rechargeable models reduce zinc oxide back to zinc through reverse reactions to achieve energy cycling, but this process still faces technical bottlenecks.
II. Diverse "Family Members": Classification and Structural Characteristics
Zinc-air batteries can be divided into multiple categories according to different classification standards, adapting to various application scenarios:
By electrolyte type, they can be classified into neutral and alkaline systems. The neutral system uses ammonium chloride and zinc chloride as electrolytes, with a structure similar to traditional zinc-manganese batteries, mostly used in low-power scenarios; the alkaline system adopts potassium hydroxide solution as the electrolyte, featuring higher energy density and being the current mainstream technical route.
By shape and power, common types include: cylindrical zinc-air batteries, which have a structure similar to cylindrical zinc-manganese batteries with air vents on the shell that need to be opened for ventilation during use; button zinc-air batteries, which are small in size with small holes on the cathode shell and widely used in small electronic devices; low-power wet batteries, which immerse electrodes in sodium hydroxide solution and are suitable for long-term low-power supply, such as navigation buoys; high-power batteries, which combine flaky activated carbon electrodes and zinc powder electrodes, are easy to carry, can be activated by injecting electrolyte, and reused by replacing the zinc electrode.
Regardless of the type, the core structure of a zinc-air battery includes five major components: the anode (a mixture of zinc powder and electrolyte), the cathode (a catalytic carbon layer responsible for capturing oxygen), the electrolyte (for ion conduction), the separator (to prevent the migration of solid particles between the two electrodes), and the sealing and insulation structure, ensuring orderly reactions while avoiding liquid leakage.
III. Advantages and Disadvantages: Two Sides of the Coin
Inherent Core Advantages
The competitiveness of zinc-air batteries stems from their unique technical characteristics. First is the ultra-high energy density. Since oxygen for the cathode comes from the air and does not occupy internal battery space, its theoretical energy density can reach 1000-1500Wh/kg, and commercial products can achieve 300-500Wh/kg, which is 2-3 times that of lithium-ion batteries, leading significantly in endurance under the same weight.
Second is safety and environmental friendliness. The electrolyte is an aqueous solution that does not contain flammable organic solvents. Even if punctured or impacted, it will not burn or explode, with extremely low thermal runaway risk. Zinc, the core material, has abundant reserves (China ranks first in the world in zinc reserves), low price, and the reaction product zinc oxide has low toxicity, easy to recycle and regenerate, without dependence on rare metals such as cobalt and lithium.
In addition, it has a significant cost advantage. The cost for mass production is about 300-500 RMB/kVAh, lower than that of lead-acid batteries. Moreover, it can achieve rapid "energy supplement" by replacing zinc electrodes, without the need to build dedicated charging stations, making it suitable for scenario-based promotion.
Urgent Technical Bottlenecks to Break Through
Despite its prominent advantages, the widespread application of zinc-air batteries is still limited by multiple challenges. Short cycle life is the biggest shortcoming of rechargeable models. During charging and discharging, zinc electrodes are prone to dendrite growth and passivation, and the activity of air electrode catalysts will gradually decay. Currently, the cycle life of secondary zinc-air batteries is mostly around 100 times, which is difficult to meet long-term use needs.
Second is strong environmental sensitivity. Carbon dioxide in the air reacts with alkaline electrolytes to form carbonate precipitates, clogging electrode pores; changes in humidity also affect performance — too low humidity reduces reaction efficiency, while too high humidity may cause liquid leakage. At the same time, low power density: the oxygen diffusion rate and electrode reaction kinetics limit the high-current output capacity, making it difficult to adapt to high-power scenarios such as electric vehicle acceleration.
In addition, mass production technology is still immature. The manufacturing of catalytic membranes and waterproof and breathable membranes still involves manual operations, resulting in poor consistency of electrode performance, which further restricts large-scale application.
IV. From Hearing Aids to Energy Storage Power Stations: In-depth Application Scenarios
With its unique combination of performance, zinc-air batteries have achieved large-scale application in specific fields and shown great potential in emerging scenarios.
In the primary application field, button zinc-air batteries almost monopolize the hearing aid market. With ultra-high energy density, they can provide续航 of several months or even more than a year, meeting the long-endurance and miniaturization needs of medical devices; cylindrical and low-power models are used in remote equipment such as railway signal lights and marine buoys, enabling long-term intermittent power supply and reducing maintenance frequency.
In the rechargeable application field, light electric vehicles are an important breakthrough. Electric bicycles powered by zinc-air batteries have appeared on the streets of Shanghai, with a cruising range of over 200 kilometers and battery replacement taking only 3 minutes, solving the pain point of slow charging of traditional electric vehicles. In the field of stationary energy storage, its advantages of low cost and high energy density make it suitable for scenarios such as grid peak regulation and photovoltaic/wind power storage, and it is expected to complement lithium-ion batteries.
V. A Promising Future: Technological Innovation Lights the Way Forward
With the advancement of materials science and manufacturing technology, the technical bottlenecks of zinc-air batteries are gradually being broken. Researchers are developing new materials such as dendrite-resistant zinc alloy anodes, high-efficiency non-precious metal catalysts, and solid electrolytes, which are expected to significantly improve cycle life and stability; optimizing battery structure design, improving air diffusion channels and electrolyte management, can enhance environmental adaptability and power density.
As a safe, environmentally friendly, and low-cost energy storage technology, zinc-air batteries occupy a special position in the wave of energy transition. In the future, with the continuous innovation of catalysts, electrode materials, and manufacturing processes, it is expected to achieve large-scale application in fields such as light transportation, distributed energy storage, and emergency power supplies, becoming an indispensable force in the battery family and injecting new vitality into the development of green energy.
