Lead Accumulator Additive for Crystal Size Control
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Solution Overview
Problem
Current methods for producing 4-basic lead sulfate for lead accumulators result in coarsely crystalline structures, leading to increased energy consumption and longer formation times, and existing additives struggle with particle size control and distribution, affecting the performance and lifespan of lead batteries.
Innovation Solution
An additive comprising finely divided 4-basic lead sulfate with an average particle size of less than 3 μm, red lead with an average particle size of less than 1.5 μm, and finely divided silica, optimized for specific surface area and particle size, is used to control crystal size and improve distribution within the battery paste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If steam treatment is used to mature positive plates into 4-basic lead sulfate, then the service life and capacity stability of lead accumulators with antimony-free alloys are improved, but the crystal size increases to >50 μm, leading to higher energy consumption and longer formation time
Solution Approach 1:
The patent applies preliminary action by adding finely ground 4-basic lead sulfate (particle size 0.5-5 μm) to the positive active mass before pasting, so that during subsequent steam treatment at 80-95°C, the 3-basic lead sulfate converts to 4-basic lead sulfate around these fine particles as nuclei, preventing excessive crystal growth while achieving the desired phase transformation for improved reliability
Solution Approach 2:
The patent changes the particle size parameter of the 4-basic lead sulfate additive to a specific range (0.5-5 μm, preferably 1-3 μm), which acts as a nucleation template during maturation. This parameter control ensures that the resulting 4-basic lead sulfate crystals remain fine-grained (5-20 μm) after steam treatment, thereby reducing formation energy consumption while maintaining the reliability benefits of 4-basic lead sulfate structure
2Reliability
If steam treatment is used to mature positive plates into 4-basic lead sulfate, then the service life is extended, but the formation time increases significantly due to larger crystal size
Solution Approach 1:
The patent applies preliminary action by incorporating pre-ground 4-basic lead sulfate with optimized particle size (0.5-5 μm) into the active mass formulation before plate assembly. During the steam maturation process, this pre-added fine material serves as nucleation sites that guide the phase transformation of 3-basic lead sulfate, ensuring rapid formation of fine-grained 4-basic lead sulfate crystals and significantly reducing the time required for complete formation while maintaining extended service life
3Manufacturing precision
If previously finely ground 4-basic lead sulfate is added to the active positive mass, then small crystal size is achieved, but the panels must be loosened by hanging or using climate membranes, representing additional effort and reduced chamber capacity
Solution Approach 1:
The patent optimizes the particle size parameter of the 4-basic lead sulfate additive to a specific range (0.5-5 μm, preferably 1-3 μm) and controls its concentration in the active mass (0.1-5% by weight). This precise parameter control allows the material to function effectively as a nucleation template during standard stacked maturation, achieving fine crystal size control without requiring panel loosening or additional handling equipment, thereby maintaining ease of manufacture while improving manufacturing precision
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the production of small-crystalline 4-basic lead sulfate with controlled crystal sizes, reducing energy requirements for battery formation, enhancing chargeability, and optimizing component distribution, leading to improved battery performance and extended lifespan with cost-effective production.
Implementation Method 1
finely divided 4-basic lead sulfate with an average particle size of less than 3 μm... finely divided silica... to prevent the particles of the 4-basic lead sulfate from agglomerating
Data Source
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AI summary
An additive for producing positive active compositions for lead accumulators based on finely divided 4-basic lead sulphate having an average particle size of less than about 3 µm and also finely divided silica, where the additive additionally contains red lead (2PbO.PbO2), is described. The finely divided silica prevents, in particular, agglomeration of the particles of the 4-basic lead sulphate, while the red lead leads to an optimized distribution of all constituents of the additive in the battery paste. The use of red lead also gives a cost advantage. Despite the replacement of part of the 4-basic lead sulphate by red lead, the properties achieved in the later use in battery operation are no worse. Thus, the batteries display, for example, improved charging behaviour and a higher high-current discharging stability. The invention further relates to the use of the additive according to at least one of claims 1 to 15 for producing positive active pastes for lead accumulators, in particular for lead accumulators having a high total discharging stability.