Lead-Acid Battery Paste With Tin Additive
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Solution Overview
Problem
Flooded lead-acid batteries with lead-antimony alloy positive electrode grids face issues with corrosion and tin migration affecting battery life and recharge characteristics, and conventional positive active material pastes have a higher α-PbO2 to β-PbO2 ratio leading to lower initial capacity and shorter life.
Innovation Solution
A positive active material paste for lead-acid batteries using a lead-antimony alloy grid with a tin or tin oxide additive, providing a molar ratio of lead to tin between 450:1 and 650:1, which converts to a higher surface area structure, reducing the α-PbO2 to β-PbO2 ratio and improving both initial capacity and battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If conventional positive active material paste is used with lead-antimony alloy grid, then the battery achieves long life due to well-defined corrosion layer, but the initial capacity is lower and battery life is shortened due to high α-PbO2 to β-PbO2 ratio
Solution Approach 1:
The patent changes the chemical composition parameter by adding tin or tin oxide to the positive active material paste, which modifies the crystalline structure formation during charging. This parameter change reduces the α-PbO2 to β-PbO2 ratio from conventional levels (1.2 or higher) to below 1.0, thereby increasing initial capacity while maintaining the benefits of lead-antimony alloy grids
Solution Approach 2:
The patent creates a composite positive active material paste by combining lead oxide with tin or tin oxide additives. This composite material approach allows the paste to form a modified lead dioxide structure during formation that provides both high initial capacity and extended battery life, resolving the trade-off between capacity and durability
2Reliability
If tin is added to positive electrode to improve corrosion layer properties, then corrosion resistance improves, but tin migrates to negative electrode grid changing half potential and adversely affecting recharge characteristics
Solution Approach 1:
The patent extracts the harmful migration effect by using tin oxide instead of metallic tin in the positive active material paste. The tin oxide remains stable during battery operation and does not migrate to the negative electrode, thereby eliminating the harmful effect while maintaining the corrosion protection benefits
Solution Approach 2:
The patent uses tin oxide as a consumable additive in the positive active material paste that provides its protective function during battery formation and operation, then remains stable without migrating. The tin oxide effectively sacrifices itself to create the protective effect without causing long-term harmful migration issues
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
The inclusion of tin in the positive active material paste results in a battery with higher initial capacity and longer life, retaining higher capacity over time and providing higher total power output compared to conventional batteries.
Implementation Method 1
a charge is applied to the battery in order to convert the lead oxide of the positive plates to lead dioxide (PbO2 or lead (IV) oxide)
Implementation Method 2
During battery discharge, the positive and negative active materials react with the sulfuric acid of the electrolyte to form lead (II) sulfate (PbSO4)
Implementation Method 3
During charging, the lead sulfate reacts with oxygen molecules from ionized water to produce lead and lead dioxide
Data Source
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AI summary
Positive active material pastes for flooded deep discharge lead-acid batteries, methods of making the same and lead-acid batteries including the same are provided. The positive active material paste includes lead oxide, a sulfate additive, and an aqueous acid. The positive active material paste contains from about 0.1 to about 1.0 wt% of the sulfate additive. Batteries using such positive active material pastes exhibit greatly improved performance over batteries with conventional positive active material pastes.