Negative Electrode Composition for High-Density Stable Secondary Batteries

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Solution Overview

Problem

Current secondary batteries do not achieve sufficient battery characteristics, such as energy density and stability, due to limitations in their configuration and materials used in the negative electrode.

Innovation Solution

A negative electrode for secondary batteries is developed, comprising a negative electrode active material layer with lithium fluoride (LiF) and lithium ethylene dicarbonate (Li–OC(═O)O–C2H4–OC(═O)O–Li), where the weight ratio of lithium fluoride to the negative electrode active material is between 0.01 and 0.2, and the weight sum of lithium fluoride and lithium ethylene dicarbonate is between 0.2 wt% and 2.0 wt%, enhancing the battery's performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If conventional negative electrode materials are used, then the battery structure is simple, but the energy density and battery characteristics are insufficient

Engineering Contradiction:

Improveenergy densityVSAvoidelectrode material composition

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent uses a composite material system consisting of graphite particles coated with amorphous carbon, where the coating layer contains both LiF and LiEDC. This composite structure combines the high capacity of graphite with the protective and conductivity-enhancing properties of the carbon coating containing specific lithium compounds, achieving superior energy density while maintaining structural integrity.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent optimizes specific parameter ranges: the LiF content is controlled at 1-20 wt% and LiEDC content at 1-20 wt% of the amorphous carbon coating layer. By precisely controlling these compositional parameters within specific ranges, the battery achieves optimal energy density and cyclability without excessive complexity.

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If the negative electrode active material layer is optimized for high capacity, then energy density improves, but the layer becomes damaged during charging and discharging

Engineering Contradiction:

Improvebattery capacityVSAvoidelectrode layer stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The amorphous carbon coating layer containing LiF and LiEDC serves as a protective cushion before the graphite particles undergo expansion and contraction during cycling. This pre-formed coating layer absorbs mechanical stress and prevents direct damage to the graphite crystalline structure, enabling high capacity operation with maintained reliability over many cycles.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The amorphous carbon coating layer acts as an intermediary between the graphite particles and the electrolyte. It mediates the interaction by providing a stable interface that protects the graphite from direct exposure to the electrolyte while allowing lithium ion transport, thus preventing electrode layer damage during charging and discharging.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If lithium fluoride and lithium ethylene dicarbonate are added to enhance performance, then energy density and cyclability improve, but the manufacturing precision requirements increase

Engineering Contradiction:

ImprovecyclabilityVSAvoidweight ratio control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent defines specific parameter ranges for LiF (1-20 wt%) and LiEDC (1-20 wt%) content in the amorphous carbon coating layer. These ranges are optimized to achieve the best balance between cyclability improvement and manufacturing feasibility, allowing sufficient tolerance in production while maintaining superior battery performance.

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

This configuration improves the battery's energy density and cyclability, preventing damage to the negative electrode active material layer during charging and discharging, while maintaining electrical conductivity and securing battery capacity.

Implementation Method 1

the negative electrode active material layer includes the negative electrode active material, lithium fluoride, and lithium ethylene dicarbonate

Methodology Applied

Scientific EffectFilm formation:

Implementation Method 2

a negative electrode for a secondary battery... includes a negative electrode active material layer

Methodology Applied

Scientific EffectIon insertion and extraction:

Data Source

PatentUS20240372097A1Negative electrode for secondary battery, and secondary battery

Publication Date: 2024.11.07 MURATA MFG CO LTD

AI summary

A secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The negative electrode includes a negative electrode active material layer. The negative electrode active material layer includes a negative electrode active material, lithium fluoride (LiF), and lithium ethylene dicarbonate (Li—OC(═O)O—C2H4—OC(═O)O—Li). A weight ratio represented by Expression (1) is greater than or equal to 0.01 and less than or equal to 0.2. A weight sum represented by Expression (2) is greater than or equal to 0.2 wt % and less than or equal to 2.0 wt %.MA=M⁢2/M⁢1(1)where:MA is the weight ratio;M1 is a ratio (wt %) of a weight of lithium fluoride to a weight of the negative electrode active material; andM2 is a ratio (wt %) of a weight of lithium ethylene dicarbonate to the weight of the negative electrode active material.MB=M⁢1+M⁢2(2)where:MB is the weight sum (wt %);M1 is the ratio (wt %) of the weight of lithium fluoride to the weight of the negative electrode active material; andM2 is the ratio (wt %) of the weight of lithium ethylene dicarbonate to the weight of the negative electrode active material.