The Dual Role of Manganese Dioxide in the Battery Industry

In zinc-manganese dry cell batteries, a classic primary battery, manganese dioxide is the core positive electrode material and also serves as a catalyst to suppress side reactions. Zinc-manganese dry batteries are categorized as acidic and alkaline. In acidic systems, such as carbon-zinc batteries, manganese dioxide (MnO2) acts as the active material in the positive electrode reaction: MnO₂ + H⁺ + e⁻ → MnO (OH). This reaction, along with the Zn-2e⁻ → Zn²⁺ reaction at the negative zinc cylinder, constitutes the overall battery reaction. In this case, MnO2 plays a central role in energy conversion, and its content directly affects the battery capacity. In alkaline systems, however, the positive electrode reaction becomes MnO₂ + H₂O + e⁻ → MnO (OH) + OH⁻. The alkaline environment allows for more efficient reduction of MnO2, resulting in a more stable discharge voltage. This increases battery capacity by approximately 30% compared to acidic systems, with utilization exceeding 90%. In addition to serving as an active electrode material, manganese dioxide also inhibits side reactions. During battery discharge, the negative electrode zinc reacts with the electrolyte to produce H₂. H₂ accumulation can lead to increased internal battery pressure, potentially causing leakage or explosion. Manganese dioxide catalyzes the oxidation of H₂, converting it into harmless water, thus ensuring battery safety. Furthermore, manganese dioxide possesses a certain degree of conductivity, which can reduce the charge transfer resistance of the positive electrode reaction, accelerate electron transfer across the electrode surface, and improve discharge efficiency.

Although manganese dioxide has traditionally been used in primary batteries, its application in secondary (rechargeable) batteries is also gaining attention through material modification methods such as nano-scaling and composite formation. In zinc-manganese secondary batteries, also known as rechargeable alkaline zinc-manganese batteries, manganese dioxide is reduced to MnO(OH) during discharge. During charging, MnO(OH) is catalyzed by manganese dioxide and oxidized back to MnO₂. However, the addition of conductive agents such as carbon black is necessary to improve reversibility. Currently, by doping with metal ions such as Co⁺ and Ni⁺, or creating layered structures like δ-MnO₂, battery cycling stability has been improved, achieving cycle lifespans of 50-100 cycles. In lithium-ion batteries, manganese dioxide, especially α-MnO₂ with its tunneling structure, can be used as a doping phase or coating material in the positive electrode, enhancing the electrode's ionic conductivity. Its lithium-ion diffusion coefficient can reach 10⁻⁷–10⁻⁹ cm²/s, improving the battery's rate capability, or rapid charge and discharge capabilities.

Manganese dioxide demonstrates its core value in the battery industry through its dual roles as an "electrode active material + catalyst." In primary batteries, it plays a key role in energy conversion and suppresses side reactions. In secondary batteries, structural design can expand its application to rechargeable systems. It serves as a low-cost catalyst replacing precious metals in novel batteries such as fuel cells and metal-air batteries. In the future, with the continuous advancement of material modification technology, the application potential of manganese dioxide in high-capacity, long-life batteries will be further unleashed, especially in the field of low-cost energy storage, where it possesses irreplaceable advantages.

Author: Hazel
Date: 2025-07-30