High Surface Area Carbon Black Expander Coating for Lead Acid Batteries

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Solution Overview

Problem

Lead acid batteries face challenges in improving cycle life, dynamic charge acceptance, and cold crank ability while maintaining or reducing water loss, particularly due to the limitations of low surface area carbon blacks which can reduce the effectiveness of organic molecule expanders in preventing PbSO4 film formation and increasing water loss.

Innovation Solution

A method of creating a negative electrode active material composition using high surface area carbon blacks with an organic molecule expander, where the carbon black is pre-wetted and added to a mixture of lead oxide and BaSO4, followed by sulfuric acid and water to form a slurry, resulting in a porous solid with a median pore size of 0.8 µm to 4 µm, allowing for increased expander coating on the lead surface and improved porosity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If low surface area carbon black is used, then cold crank ability is maintained, but cycle life and dynamic charge acceptance deteriorate

Engineering Contradiction:

Improvecycle lifeVSAvoidcold crank ability

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes the surface area parameter of carbon black from conventional low values to at least 250 m²/g, which fundamentally alters the electrode's electrochemical performance. This parameter change enables simultaneous improvement in cycle life and dynamic charge acceptance while maintaining cold crank ability through the synergistic effect of high surface area carbon black and organic molecule expander.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If high surface area carbon black is used, then cycle life and dynamic charge acceptance improve, but water loss increases due to reduced expander effectiveness

Engineering Contradiction:

Improvecycle lifeVSAvoidwater loss

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The patent merges high surface area carbon black with organic molecule expander in a synergistic combination. The expander coats the carbon black surface, preventing direct exposure that would cause water loss, while still allowing the high surface area carbon to provide improved cycle life and dynamic charge acceptance. This combination resolves the contradiction by making the carbon black's high surface area beneficial without triggering excessive water loss.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The organic molecule expander acts as an intermediary between the high surface area carbon black and the electrolyte. It forms a coating layer that mediates the interaction, preventing harmful direct contact between carbon black and electrolyte that would cause water loss, while still permitting the carbon black to fulfill its electrochemical function for improved cycle life and charge acceptance.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If high surface area carbon black is used, then dynamic charge acceptance improves, but PbSO4 film formation increases due to insufficient expander coating

Engineering Contradiction:

Improvedynamic charge acceptanceVSAvoidPbSO4 film prevention

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The organic molecule expander is applied in advance to coat the high surface area carbon black surface before the battery operates. This preliminary coating action ensures that when the battery cycles, the carbon black surface is already protected, preventing PbSO4 film formation while allowing the high surface area to enhance dynamic charge acceptance from the outset.

Inventive Principle:

Principle #10Preliminary action

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 enhances dynamic charge acceptance and cycle life while maintaining or improving cold crank ability and reducing water loss, by ensuring a sufficient amount of expander coats the lead surface, preventing PbSO4 film formation and maintaining electrode porosity.

Implementation Method 1

ensuring a sufficient amount of expander coats the lead surface, preventing PbSO4 film formation

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

high surface area carbon blacks with an organic molecule expander... resulting in a porous solid with a median pore size of 0.8 µm to 4 µm

Methodology Applied

Scientific EffectPorosity: Porosity

Data Source

PatentEP2901515B1Method of making active material compositions comprising high surface area carbonaceous materials

Publication Date: 2019.05.22 CABOT CORP

Figure 1A~1B
Figure 2

AI summary

Disclosed herein are negative active material compositions, comprising: a carbonaceous material (6') having a surface area of at least 250 m2/g; and an organic molecule expander (4'), wherein the ratio of carbonaceous material to expander ranges from 5:1 to 1:1, and wherein the composition has a median pore size ranging from 0.8 μιη to 4 μm. Also disclosed are electrodes and batteries comprising such compositions, and methods of making thereof.