Semi-Solid Electrode Pre-Lithiation for Stable SEI Formation

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Solution Overview

Problem

Lithium-ion electrodes, particularly anodes, suffer from irreversible capacity loss and volumetric expansion during the initial cycling step of battery formation due to lithium ion transfer, leading to reduced charge capacity and mechanical damage.

Innovation Solution

Pre-lithiation of semi-solid electrodes during the mixing of the electrode slurry forms a solid-electrolyte interface (SEI) layer before electrochemical cell formation, using lithium metal to pre-lithiate the active material and protect it from ambient environment, thereby reducing irreversible capacity loss and mechanical stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lithium-ion electrodes are used in conventional form, then the battery can operate normally, but irreversible capacity loss occurs during initial cycling due to lithium ion transfer to form SEI layer

Engineering Contradiction:

Improvecharge capacity retentionVSAvoidlithium ion consumption

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The patent applies preliminary action by pre-lithiating the anode material before battery assembly. Lithium metal is mixed with the anode slurry during electrode preparation, providing lithium ions in advance. This preliminary lithium supply ensures that when the battery undergoes initial cycling, the pre-added lithium forms the SEI layer instead of consuming lithium from the cathode, thereby preventing irreversible capacity loss and maintaining charge capacity retention.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If lithium ions are transferred during formation stage, then SEI layer is formed on anode, but volumetric expansion and mechanical damage occur

Engineering Contradiction:

Improvemechanical stabilityVSAvoidvolumetric expansion

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent uses preliminary action by incorporating lithium metal into the anode slurry during the mixing stage. This pre-added lithium ensures that the SEI layer formation occurs with pre-supplied lithium rather than causing volumetric expansion from lithium insertion into the anode structure. The preliminary lithium supply prevents mechanical damage by avoiding the expansion stresses that would otherwise occur during initial lithium insertion.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If conventional electrode preparation is used, then manufacturing process is simple, but irreversible capacity loss reduces battery performance

Engineering Contradiction:

Improvebattery performanceVSAvoidirreversible capacity loss

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent applies preliminary action by adding lithium metal to the anode slurry during the conventional electrode mixing process. This modification maintains the simplicity of the manufacturing process while fundamentally improving battery performance. The pre-added lithium eliminates irreversible capacity loss by providing lithium ions for SEI layer formation before battery assembly, ensuring that all lithium cycles contribute to reversible capacity and overall productivity.

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 maintains initial capacity of the cathode, reduces volumetric expansion, and enhances the mechanical stability and operational lifetime of electrochemical cells by forming the SEI layer before initial charging, minimizing lithium ion consumption from the cathode and preventing mechanical damage.

Implementation Method 1

The lithium metal is configured to form a solid-electrolyte interface (SEI) layer on a surface of the active material

Methodology Applied

Scientific EffectSolid-electrolyte interface (SEI) layer formation:

Implementation Method 2

lithium (as lithium metal, a lithium-containing material, and/or a lithium metal equivalent) in an amount sufficient to substantially pre-lithiate the active material

Methodology Applied

Scientific EffectLithium ion transfer: Diffusion

Data Source

PatentUS11804595B2Pre-lithiation of electrode materials in a semi-solid electrode

Publication Date: 2023.10.31 24M TECHNOLOGIES INC

AI summary

Embodiments described herein relate generally to electrochemical cells having pre-lithiated semi-solid electrodes, and particularly to semi-solid electrodes that are pre-lithiated during the mixing of the semi-solid electrode slurry such that a solid-electrolyte interface (SEI) layer is formed in the semi-solid electrode before the electrochemical cell formation. In some embodiments, a semi-solid electrode includes about 20% to about 90% by volume of an active material, about 0% to about 25% by volume of a conductive material, about 10% to about 70% by volume of a liquid electrolyte, and lithium (as lithium metal, a lithium-containing material, and/or a lithium metal equivalent) in an amount sufficient to substantially pre-lithiate the active material. The lithium metal is configured to form a solid-electrolyte interface (SEI) layer on a surface of the active material before an initial charging cycle of an electrochemical cell that includes the semi-solid electrode.