Pre-Lithiated Negative Electrode for Longer-Cycle Lithium Batteries

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Solution Overview

Problem

Lithium secondary batteries face degradation due to reduced lithium source and initial irreversible capacity loss, leading to poor cycle characteristics, and existing solutions either increase cell thickness or require inconvenient electrolyte injection processes.

Innovation Solution

A lithium secondary battery with a pre-lithiated negative electrode, where the negative electrode's charge capacity is smaller than the positive electrode's due to pre-lithiation, allowing excessive lithium to be electroplated and function as an additional lithium source, reducing initial irreversibility and supplementing lithium during degradation without the need for a separate lithium electrode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a separate lithium electrode is added to supplement lithium during battery degradation, then the lithium source is replenished, but the cell thickness increases

Engineering Contradiction:

Improvelithium sourceVSAvoidcell thickness

Core Design Contradiction:

Quantity of substanceVSLength of stationary object

Solution Approach 1:

The patent merges the lithium supplement function into the negative electrode itself by incorporating lithium-containing materials (such as lithium metal particles, lithium alloy particles, or lithium compounds) directly into the negative electrode structure. This integration eliminates the need for a separate lithium electrode, thereby maintaining the cell thickness while still providing lithium supplementation during battery degradation

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The negative electrode is designed to perform multiple functions: it serves as both the active electrode material host and the lithium supplement reservoir. By making the negative electrode multi-functional, the patent eliminates the need for a dedicated lithium electrode, thus avoiding increased cell thickness while ensuring lithium availability throughout the battery lifecycle

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Quantity of substance

If electrolyte injection process is used to supplement lithium, then lithium source degradation is addressed, but the process becomes inconvenient and complex

Engineering Contradiction:

Improvelithium sourceVSAvoidmanufacturing process

Core Design Contradiction:

Quantity of substanceVSEase of manufacture

Solution Approach 1:

The patent incorporates lithium-containing materials into the negative electrode during the initial manufacturing process, performing the lithium supplementation action in advance. This preliminary incorporation eliminates the need for subsequent electrolyte injection operations, simplifying the manufacturing process and making it more convenient while ensuring lithium availability when needed

Inventive Principle:

Principle #10Preliminary action

3Reliability

If pre-lithiation is performed to reduce initial irreversible capacity loss, then cycle characteristics are improved, but the negative electrode charge capacity becomes smaller than positive electrode

Engineering Contradiction:

Improvecycle characteristicsVSAvoidcharge capacity

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies partial pre-lithiation, where lithium-containing materials are incorporated into the negative electrode in a controlled amount that is sufficient to compensate for initial irreversible capacity loss and provide lithium supplementation during degradation, but not so much as to create a significant capacity imbalance between electrodes. This balanced approach improves cycle characteristics while maintaining acceptable charge capacity

Inventive Principle:

Principle #16Partial or excessive 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

The battery exhibits excellent cycle characteristics by reducing lithium source degradation and initial irreversible capacity loss, functioning as an additional lithium source without increasing cell thickness or requiring electrolyte injection processes.

Implementation Method 1

allowing excessive lithium to be electroplated and function as an additional lithium source

Methodology Applied

Scientific EffectElectroplating: Electroplating

Implementation Method 2

a process of intercalating and deintercalating lithium ions from the positive electrode active material of the positive electrode into and out of the negative electrode active material of the negative electrode

Methodology Applied

Scientific EffectIntercalation: Absorption (physical)

Data Source

PatentEP3565035B1Lithium secondary battery and manufacturing method for preparing the same

Publication Date: 2023.12.13 LG ENERGY SOLUTION LTD

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AI summary

A lithium secondary battery including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, wherein the negative electrode is lithiated by pre-lithiation, a total capacity of a negative electrode active material of the negative electrode is larger than a total capacity of a positive electrode active material of the positive electrode, and a charge capacity of the negative electrode is smaller than a charge capacity of the positive electrode by the pre-lithiation.