Graphite Particles with High-Dielectric Inorganic Solid

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Solution Overview

Problem

Conventional lithium-ion secondary batteries experience a rapid decline in durability and internal resistance during charge and discharge cycles due to solvent decomposition and lack of protection for the positive electrode active material.

Innovation Solution

Incorporating a high-dielectric inorganic solid with ion conductivity into graphite material particles to trap solvents, reduce electrolyte decomposition, and prevent corrosion, thereby enhancing the battery's durability and maintaining low internal resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a coating layer including lithium ion conducting solid electrolyte and conductive aid is applied to active material, then internal resistance is reduced and active material is protected from deformation, but durability to charge and discharge operations rapidly declines

Engineering Contradiction:

Improveinternal resistance stabilityVSAvoiddurability to charge and discharge operations

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The invention uses a composite coating layer comprising both a lithium ion conducting solid electrolyte and a high-dielectric inorganic solid. This composite structure combines the ion conductivity benefits with the solvent-trapping and polarization capabilities of the high-dielectric material, achieving both low internal resistance and high durability without the rapid degradation seen in conventional single-material coatings

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The high-dielectric inorganic solid acts as an intermediary between the electrolyte and the active material surface. It traps free solvent molecules and polarizes acids produced during decomposition, preventing direct harmful interactions while maintaining ion transport pathways, thus protecting the system over extended cycling

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If conventional coating layers are used, then initial charge and discharge cycles show advantageous effects, but rapid decline in durability occurs during extended cycling

Engineering Contradiction:

Improveinitial charge and discharge performanceVSAvoidextended cycle durability

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The high-dielectric inorganic solid provides beforehand cushioning by trapping free solvent and polarizing decomposition products before they can cause harmful effects. This preventive mechanism is in place from the initial cycles and continues to protect the system throughout extended operation, preventing the rapid durability decline observed with conventional coatings

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If high-dielectric inorganic solid is integrated into graphite particles, then solvent decomposition is reduced and positive electrode is protected, but manufacturing complexity increases

Engineering Contradiction:

Improveelectrolyte stability and electrode protectionVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention merges the high-dielectric inorganic solid directly into the graphite particle structure itself, creating an integrated composite particle. This eliminates the need for separate coating application steps and simplifies manufacturing compared to applying complex multi-layer coatings, while achieving superior electrolyte stability and electrode protection

Inventive Principle:

Principle #5Merging (Combining)

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 integration of high-dielectric inorganic solids within graphite particles stabilizes the electrolyte, prevents solvent decomposition, and protects the positive electrode, resulting in improved durability and reduced resistance during charge and discharge cycles.

Implementation Method 1

the high-dielectric inorganic solid can be polarized to trap an acid, which is produced when a fluoro anion or a solvent is decomposed on the graphite particle surface

Methodology Applied

Scientific EffectPolarisation: Polarisation

Implementation Method 2

the high-dielectric inorganic solid has at least one ion conductivity selected from Li ion conductivity, Na ion conductivity, and Mg ion conductivity... can trap a free solvent in an electrolytic solution so that quasi-solvation state can be formed to effectively stabilize the solvent

Methodology Applied

Scientific EffectSolvation: Solvation

Data Source

PatentUS20220166059A1Graphite material particles for use in lithium-ion secondary batteries, electrode for use in lithium-ion secondary batteries, and method of producing graphite material particles

Publication Date: 2022.05.26 HONDA MOTOR CO LTD

AI summary

Provided are graphite material particles that are for use in lithium-ion secondary batteries, make lithium-ion secondary batteries less vulnerable to an increase in internal resistance during charge and discharge cycles, and allow lithium-ion secondary batteries to have high durability to charge and discharge cycles. The graphite material particles for use in a lithium-ion secondary battery each have a structure including: a graphite particle; and a high-dielectric inorganic solid located in and integrated with the graphite particle. The high-dielectric inorganic solid preferably has at least one ion conductivity selected from Li ion conductivity, Na ion conductivity, and Mg ion conductivity, and preferably has an ionic conductivity of 10−7 S/cm or more and a relative permittivity of 10 or more when in the form of a powder.