Gelling Powder Cathode for Lithium Battery Voltage Stability

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Solution Overview

Problem

Lithium batteries with low viscosity liquid electrolytes face challenges in achieving a robust mechanical design and stable voltage curves due to cathode expansion, which leads to void formation and erratic voltage fluctuations, while increasing electrolyte amounts or pressure can reduce battery capacity and energy density, and result in self-discharge issues from uncontrolled lithium deposition.

Innovation Solution

Incorporating a gelling powder into the cathode materials during formation, causing the liquid electrolyte to gel after the battery is sealed, which adheres to the cathode and prevents void formation, maintaining smooth voltage curves and reducing self-discharge by minimizing free liquid electrolyte.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the amount of liquid electrolyte is increased to fill voids formed during cathode expansion, then voltage stability is improved, but battery capacity and energy density decrease

Engineering Contradiction:

Improvevoltage stabilityVSAvoidbattery capacity

Core Design Contradiction:

Stability of the object's compositionVSQuantity of substance

Solution Approach 1:

The patent changes the physical state parameter of the electrolyte from liquid to gel phase by incorporating gelling powder. This transformation allows the electrolyte to maintain stable contact with the cathode during expansion without requiring increased electrolyte quantity, thus resolving the contradiction between voltage stability and battery capacity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite electrolyte system by combining gelling powder with liquid electrolyte components. This composite structure provides both the stability of gel (maintaining contact during cathode expansion) and the ionic conductivity needed for battery operation, eliminating the need to increase electrolyte amount while preserving voltage stability.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If stack pressure is increased to prevent void formation during cathode expansion, then voltage stability is improved, but battery case thickness and rigidity increase, reducing energy density

Engineering Contradiction:

Improvevoltage stabilityVSAvoidenergy density

Core Design Contradiction:

Stability of the object's compositionVSWeight of moving object

Solution Approach 1:

The patent changes the viscosity parameter of the electrolyte by introducing gelling powder, transforming it from a low-viscosity liquid to a gel with higher viscosity and elastic properties. This allows the electrolyte to resist void formation through its gel structure rather than requiring high stack pressure, thereby maintaining voltage stability without increasing case thickness.

Inventive Principle:

Principle #35Parameter changes

3Power

If low viscosity liquid electrolyte is used to provide high ionic conductivity, then power output is improved, but uncontrolled lithium deposition and self-discharge increase

Engineering Contradiction:

Improvepower outputVSAvoidself-discharge

Core Design Contradiction:

PowerVSObject-generated harmful factors

Solution Approach 1:

The patent modifies the viscosity parameter of the electrolyte by adding gelling powder, transforming it from a low-viscosity liquid to a gel. This increases the electrolyte's resistance to flow and movement, preventing uncontrolled lithium ion migration and deposition while maintaining sufficient ionic conductivity for power output through the gel matrix.

Inventive Principle:

Principle #35Parameter changes

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 gelling powder stabilizes voltage curves, increases energy density, and reduces self-discharge by ensuring consistent ionic conduction and preventing lithium deposition on internal surfaces, without compromising battery capacity.

Implementation Method 1

Incorporating a gelling powder into the cathode materials during formation, causing the liquid electrolyte to gel after the battery is sealed

Methodology Applied

Scientific EffectGel formation: Gel

Implementation Method 2

the gelled electrolyte may adhere to the cathode material and prevent or reduce void formation as the porosity of the cathode increases

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 3

a liquid electrolyte to transport positively charged ions between the cathode and the anode

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Data Source

PatentUS20230187608A1Cathode and method of forming the same

Publication Date: 2023.06.15 MEDTRONIC INC

AI summary

An electrochemical cell includes an anode, a cathode, a separator, and a liquid electrolyte. The cathode includes an active material, a conductive material, a binder, and a gelling powder. The separator is arranged between the anode and the cathode. The separator is configured to prevent direct contact between the anode and the cathode. The liquid electrolyte transports positively charged ions between the cathode and the anode.