Lithium-Free Solid-State Battery Anode with Dual-Size Carbon Packing

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Solution Overview

Problem

All-solid-state lithium ion secondary batteries with lithium-free negative electrodes face challenges in maximizing the contact area between the negative electrode and the solid electrolyte due to large voids between carbon materials, even with warm isostatic pressing, limiting battery performance.

Innovation Solution

Incorporating two or more carbon materials with different particle sizes in the negative electrode active material layer to reduce voids and increase the contact area with the solid electrolyte before and after isostatic pressurization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a lithium-free negative electrode with single carbon material is used, then safety is improved by avoiding lithium metal, but the contact area with solid electrolyte is insufficient due to large voids

Engineering Contradiction:

ImprovesafetyVSAvoidcontact area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent uses a composite structure of two different carbon materials (graphite and amorphous carbon) in the negative electrode. Graphite provides lithium insertion/extraction sites while amorphous carbon fills voids and improves contact with solid electrolyte, achieving both safety and adequate contact area

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent utilizes the porous structure of amorphous carbon to fill the large voids between graphite particles. This porous material penetrates into the voids and creates additional contact pathways with the solid electrolyte, increasing the effective contact area without compromising the lithium-free safety advantage

Inventive Principle:

Principle #31Porous materials

2Area of stationary object

If warm isostatic pressing is applied to reduce voids, then contact area is improved, but the effect is insufficient for lithium-free negative electrodes with large voids

Engineering Contradiction:

Improvecontact areaVSAvoidpressing effectiveness

Core Design Contradiction:

Area of stationary objectVSProductivity

Solution Approach 1:

The patent performs preliminary action by incorporating amorphous carbon material into the electrode structure before isostatic pressing. This pre-positioned porous material is strategically placed to fill voids, so that when isostatic pressing is subsequently applied, the void reduction is significantly enhanced compared to pressing alone

Inventive Principle:

Principle #10Preliminary action

3Quantity of substance

If lithium metal is used as negative electrode active material, then capacity density is increased (10 times that of graphite), but the risk of explosion and dendrite formation increases

Engineering Contradiction:

Improvecapacity densityVSAvoidexplosion risk

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the high-capacity but hazardous lithium metal with a lithium-free composite carbon electrode. While individual carbon particles have lower capacity than lithium metal, the composite structure compensates through increased surface area and improved electrolyte contact, providing a safer alternative that accepts the trade-off of slightly lower theoretical capacity for dramatically improved safety

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent introduces amorphous carbon as an intermediary material between the current collector and the solid electrolyte. This intermediary serves multiple functions: it provides additional lithium insertion sites, fills voids to improve contact, and prevents direct contact between any potential lithium deposits and the electrolyte, thereby eliminating explosion risk while maintaining usable capacity

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enhances the initial charge/discharge efficiency and lifetime performance of the battery by improving the contact area between the negative electrode and the solid electrolyte, leading to better battery performance.

Implementation Method 1

a solid electrolyte layer, and a negative electrode active material layer disposed between the solid electrolyte layer and the negative electrode current collector

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

even with warm isostatic pressing (WIP), making it difficult to maximize the performance of the battery

Methodology Applied

Scientific EffectPressure application: Compression

Data Source

PatentUS20250309243A1All-Solid-State Lithium Ion Secondary Batteries And Lithium-Free Negative Electrodes Therefor

Publication Date: 2025.10.02 LG ENERGY SOLUTION LTD

AI summary

An all-solid-state lithium ion secondary battery includes the lithium-free negative electrode having two or more carbon materials with different particle sizes to increase the contact area with the solid electrolyte. The all-solid-state lithium ion secondary battery includes a positive electrode, a solid electrolyte layer, a negative electrode current collector, and a negative electrode active material layer disposed between the solid electrolyte layer and the negative electrode current collector, wherein the negative electrode active material layer includes a first carbon material; a second carbon material; and Ag; wherein the first carbon material and the second carbon material have different average particle sizes.