All-Solid Battery Anode Surface Roughness Control

Solution Overview

Problem

All-solid batteries face challenges with increased resistance and short circuits due to insufficient contact between the anode and solid electrolyte layers, which affects their safety and cycle characteristics.

Innovation Solution

The battery design includes an anode layer with a first anode active material layer having a maximum roughness depth of 3.5 micrometers or less, and a pressing process to enhance contact between the anode and solid electrolyte layers, reducing the likelihood of cracks and short circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the anode active material layer is made smooth, then contact with solid electrolyte is improved, but surface area for lithium insertion/extraction is reduced

Engineering Contradiction:

Improvecontact between anode and solid electrolyteVSAvoidsurface area of anode active material layer

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent applies local quality by creating a dual-roughness structure: the bulk of the anode active material layer maintains high surface area for lithium reactions, while only the outermost surface (within 3.5 micrometers) is controlled to be smooth for optimal solid electrolyte contact. This localized differentiation resolves the contradiction between needing large surface area and good contact.

Inventive Principle:

Principle #3Local quality

2Reliability

If pressing force is increased to improve contact, then resistance is reduced, but solid electrolyte layer may crack

Engineering Contradiction:

Improvecontact between layersVSAvoidintegrity of solid electrolyte layer

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent applies preliminary anti-action by pre-smoothing the anode active material layer surface before assembly. This preventive measure reduces the pressing force needed to achieve good contact, thereby preventing cracks in the solid electrolyte layer that would otherwise occur with high pressing forces.

Inventive Principle:

Principle #9Preliminary anti-action

3Area of stationary object

If roughness depth is increased to maintain surface area, then lithium insertion/extraction sites are increased, but contact with solid electrolyte becomes insufficient

Engineering Contradiction:

Improvesurface area of anode active material layerVSAvoidcontact between anode and solid electrolyte

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The patent applies local quality by creating a dual-roughness structure: the bulk of the anode active material layer maintains high surface area for lithium reactions, while only the outermost surface (within 3.5 micrometers) is controlled to be smooth for optimal solid electrolyte contact. This localized differentiation resolves the contradiction between needing large surface area and good contact.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11450881B2All-solid secondary battery and method for preparing all-solid secondary battery

Publication Date: 2022.09.20 SAMSUNG ELECTRONICS CO LTD

AI summary

An all-solid secondary battery including: an anode layer including a first anode active material layer; a cathode layer including a cathode active material layer; a solid electrolyte layer between the anode layer and the cathode layer; and an anode current collector on the anode layer and opposite the solid electrolyte layer, wherein a maximum roughness depth Rmax of a surface of the first anode active material layer is about 3.5 micrometers or less.