Stannous sulfate: Preparation Method by Tin Powderization Waste, Applications as Electrolyte Additive and Nano-filler

General Description

The synthesis of stannous sulfate from tin powderization waste involves a two-step process, starting with the conversion of tin powder to stannous chloride using hydrochloric acid, followed by reacting the produced SnCl2 with ammonium sulfate to form stannous sulfate. This method efficiently recycles tin waste, aligning with sustainable development goals by promoting resourceful consumption and production. Stannous sulfate has significant applications, including as an electrolyte additive in lead-acid batteries, where it enhances battery performance by reducing lead sulfate crystal size, and as a nano-filler in polyvinylidene fluoride nanocomposites, improving their phase transformation and material properties for advanced applications in smart sensing devices.

Figure 1. Stannous sulfate

Preparation method by tin powderization waste

Stannous sulfate can be synthesized from tin powderization waste, leveraging a two-step process that begins with the production of stannous chloride (SnCl2) followed by its conversion to SnSO4. Initially, tin powder, obtained as a waste by-product from the tin powderization process, is utilized as the raw material. This approach aligns with the Sustainable Development Goals (SDG) program by promoting sustainable consumption and production systems through the recycling of industrial waste. In the first step, tin powder with a particle size of 500 mesh is reacted with 12 M hydrochloric acid (HCl) at 80°C. This reaction yields stannous chloride (SnCl2) with an efficiency of 95%, indicating a high conversion rate from tin powder to SnCl2.  Following the successful synthesis of SnCl2, it is then converted into stannous sulfate through a reaction with ammonium sulfate ((NH4)2SO4). This conversion is facilitated using stirring techniques, ensuring thorough mixing and reaction of SnCl2 with (NH4)2SO4. The presence of stannous sulfate is confirmed through Fourier Transform Infrared (FT-IR) spectroscopy, with the spectrum showing characteristic sulfate group signals around 1181 cm−1.  This method not only demonstrates an efficient way to recycle tin waste but also contributes to the production of valuable tin-derived compounds like stannous sulfate, which have wide applications, including their use as catalysts in the formation of Sulfated Tin Oxide catalyst products. ¹

Applications

Applications as electrolyte additive

Stannous sulfate serves as a significant electrolyte additive in lead-acid batteries, particularly those utilizing a novel ultrafine leady oxide. This innovative approach in battery manufacturing explores the potential of SnSO4 to enhance the microstructure of the positive plate and improve the overall electrochemical performance of the battery. The novel leady oxide, created through the leaching of spent lead paste in a citric acid solution, forms the basis for the working electrode (WE) and the active material in the positive plate of a test battery with a capacity of 1.85 Ah. Electrochemical cyclic voltammetry (CV) tests reveal that Stannous sulfate, when added to the electrolyte, influences the size and formation of lead sulfate (PbSO4) crystals. Without Stannous sulfate, larger column-shaped PbSO4 crystals dominate, which are less desirable for battery efficiency. The addition of Stannous sulfate results in significantly smaller PbSO4 crystals, suggesting an enhanced microstructure conducive to better battery performance. Moreover, scanning electron microscopy (SEM) studies confirm that Stannous sulfate reduces the particle size of lead dioxide (PbO2) in the positive active materials during the charging process. This reduction in particle size is crucial for minimizing the formation of large, irreversible sulfation particles during the charge/discharge cycles, thereby extending the battery's life and improving its reliability. Thus, stannous sulfate emerges as a valuable additive in lead-acid battery technology, offering a promising route to optimize battery performance through advanced material engineering. ²

Applications as nano-filler

Stannous sulfate nanoparticles have been identified as a potent nano-filler for polyvinylidene fluoride nanocomposites, markedly improving their properties and enabling significant phase transformation. These nanoparticles are synthesized using an in situ deposition method and further enhanced with PEG as a nonionic polymeric surfactant, resulting in Stannous sulfate loadings within the PVDF matrix ranging from 0 to 4% w/w. Characterization through XRD, FTIR, SEM, EDS, TG/DTA, DSC, and UV–vis spectrum analysis confirms the uniform dispersion of these 45 nm diameter nanoparticles. Crucially, the addition of Stannous sulfate nanoparticles prompts a complete shift from PVDF's alpha (α) phase to the more desirable beta (β) phase, evidenced by XRD analysis showing a 2θ value shift to 20.75°. This phase transition enhances the material's piezoelectric and ferroelectric capabilities. Furthermore, increased nanoparticle loadings lead to heightened UV absorbance and reduced glass transition (Tg) and decomposition temperatures (Td), indicating improved material performance. Consequently, these advancements position PVDF/SnSO4 nanocomposites as promising materials for smart sensing devices, showcasing the versatility and efficacy of Stannous sulfate nanoparticles in polymer enhancement. ³

Reference

1. Tajuddin CA. Stannous chloride (SnCl2) and stannous sulfate (SnSO4) synthesis from tin powderization waste. IOP Conference Series: Earth and Environmental Science. 2021; 171: 1.

2. Wang Q. Stannous sulfate as an electrolyte additive for lead acid battery made from a novel ultrafine leady oxide. Journal of Power Sources. 2015; 285: 485-492.

3. Rathore S, Hari Madhav GJ. Efficient nano-filler for the phase transformation in polyvinylidene fluoride nanocomposites by using nanoparticles of stannous sulfate. Materials Research Innovations. 2019; 1(1): 183-190.

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