Chinese researchers have developed a new strategy to improve the capacity of manganese-based semi-solid battery systems.

​Using the new method, scientists at Shanghai University reported a 409 percent boost in battery capacity over the reported manganese-sulfate (MnSO₄)- based electrolyte benchmark when they switched to a Manganese dioxide (MnO₂) semi-solid slurry electrolyte.

​The significant improvement in capacity was observed even when the systems were operated at higher current densities.

​These modifications could make them a suitable candidate for large-scale energy storage systems, researchers said.

Conventional manganese-based systems have been a preferred choice for battery materials as manganese is environmentally safe, low-cost, and is abundantly available.

​But the traditional redox-based batteries have limited solubility in electrolyte and restrict the amount of energy they can store.

​The alternative solid MnO₂ could overcome the challenge as it increases the active-material content. However, these semi-solid flow batteries typically cannot charge or discharge as quickly as desired because the chemical reactions occur slowly. This makes them unsuitable for operations at high charge-discharge rates,

​To overcome the two limitations of the conventional Mn-based systems, the team, instead of relying solely on dissolved manganese salts, added solid MnO₂ into the electrolyte. This resulted in a slight change in the electrochemical reaction pathway, the study reported.

​”During discharge, solid MnO₂ is electrochemically converted into soluble Mn²⁺, allowing the battery to access more active material without being constrained by the initial solubility limit,” the researcher said.

​This innovative way of increasing the amount of active manganese helped reduce the common-ion effect that impacts sulfuric acid electrolytes, limiting their solubility.

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