Solid-State Li-CFx Battery with β-Li3PS4 Electrolyte

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Solution Overview

Problem

Li—CFx batteries face limitations such as heat generation, volume expansion, poor electrode kinetics, low electronic conductivity, and flammability concerns due to solvation chemistry, restricting their widespread application.

Innovation Solution

A solid-state lithium carbon monofluoride battery design incorporating a Li anode, a bi-functional β-Li3PS4 solid electrolyte, and a cathode with CFx and β-Li3PS4, which allows for amorphous LiF formation, eliminating solvation and enhancing capacity utilization beyond theoretical limits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If liquid electrolyte is used in Li-CFx batteries, then ionic conductivity is improved, but heat generation and flammability occur

Engineering Contradiction:

Improveionic conductivityVSAvoidheat generation and flammability

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the physical state of the electrolyte from liquid to solid (β-Li3PS4), fundamentally altering the parameters of the system. This solid-state electrolyte eliminates the flammability and heat generation issues associated with liquid electrolytes while maintaining ionic conductivity through the solid material's intrinsic properties

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the liquid electrolyte system with a solid electrolyte system, substituting one material state for another. The solid β-Li3PS4 electrolyte provides ionic conduction without the harmful thermal and combustion properties of liquid electrolytes

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If solvent intercalation occurs during discharge, then LiF crystallization is facilitated, but volume expansion results

Engineering Contradiction:

ImproveLiF formationVSAvoidcathode volume

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent eliminates solvent intercalation by using a solid-state electrolyte, which changes the discharge mechanism. Without liquid solvent involvement, the cathode avoids the volume expansion that would result from solvent insertion and LiF crystallization, while still achieving amorphous LiF formation through the solid-state reaction pathway

Inventive Principle:

Principle #35Parameter changes

3Productivity

If LiF crystallization occurs, then discharge reaction is completed, but heat generation increases

Engineering Contradiction:

Improvedischarge completionVSAvoidheat generation

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The patent changes the phase of LiF formation from crystalline to amorphous through the solid-state reaction pathway. This parameter change eliminates the high enthalpy of crystallization (26.91 kJ mol−1) that causes heat generation, while still achieving complete discharge reaction and LiF formation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent substitutes the crystallization process with an amorphous formation process. Instead of LiF crystallizing with its associated heat release, the solid-state electrolyte enables amorphous LiF formation, completing the discharge reaction without significant heat generation

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Device complexity

If conventional Li-CFx battery design is used, then simple structure is maintained, but capacity utilization is limited to theoretical values

Engineering Contradiction:

Improvebattery structureVSAvoidcapacity utilization

Core Design Contradiction:

Device complexityVSQuantity of substance

Solution Approach 1:

The patent changes the electrolyte from liquid to solid state, which fundamentally alters the electrochemical reaction pathway. This parameter change enables capacity utilization exceeding theoretical limits by eliminating solvent-related limitations and enabling more efficient Li-ion transport and reaction kinetics

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite cathode structure containing CFx and carbon compounds, combined with solid-state β-Li3PS4 electrolyte. This composite approach enables enhanced capacity utilization through synergistic effects while maintaining a practical battery structure

Inventive Principle:

Principle #40Composite materials

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 solid-state design achieves a capacity utilization greater than 865 mAh/g, mitigates volume expansion and heat generation, and provides excellent rate performance and stability, surpassing conventional Li—CFx batteries in energy density and shelf life.

Implementation Method 1

Solid-state Li-ion conductors offer a step away from the solvation chemistry while offering better mechanical properties, electrochemical and thermal stability

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 2

CFx+xLi+·S+xe−→C(Li+·S−F−)x→C+xLiF+xS (Cathode)

Methodology Applied

Scientific EffectElectrochemical reduction: Redox Reactions

Data Source

PatentUS9786915B2All-solid state lithium carbon monofluoride batteries

Publication Date: 2017.10.10 UT BATTELLE LLC

AI summary

A solid state lithium carbon monofluoride battery includes an anode comprising Li, a solid electrolyte, and a cathode including CFx and LPS. The cathode can also include a carbon compound. The solid electrolyte can include LPS. The LPS can include β-Li3PS4. The cathode LPS can include β-Li3PS4. A method of making a battery is also disclosed.