MSi2 Anode for All-Solid-State Battery Pressure Control

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Solution Overview

Problem

All-solid-state batteries using Si-based anode active materials face issues with expansion during charging, leading to increased confining pressure and potential cracking or high stress on the battery structure.

Innovation Solution

The use of MSi2 (where M is Yb, Er, or Lu) as an anode active material with an AlB2-type crystal structure, which absorbs Li between Si layers, reducing expansion and thus suppressing the increase in confining pressure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If Si-based anode active material is used, then theoretical capacity per volume is increased, but expansion during charging occurs leading to increased confining pressure

Engineering Contradiction:

Improvetheoretical capacityVSAvoidconfining pressure

Core Design Contradiction:

Quantity of substanceVSStress or pressure

Solution Approach 1:

The patent uses MSi2 intermetallic compounds (where M is a rare earth element) as composite anode materials that combine the high capacity benefits of silicon with the structural stability of intermetallic compounds, resolving the contradiction between high capacity and low expansion

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the crystal structure parameter from amorphous or simple crystalline silicon to AlB2-type intermetallic structure, which fundamentally alters the expansion behavior during lithium insertion while maintaining high capacity

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If Si-based anode active material is used, then theoretical capacity per volume is increased, but structural integrity deteriorates due to cracking and high stress

Engineering Contradiction:

Improvetheoretical capacityVSAvoidstructural integrity

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The MSi2 intermetallic compound structure provides inherent structural strength and crack resistance while maintaining the high lithium capacity of silicon-based materials, resolving the contradiction between capacity and structural integrity

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The AlB2-type crystal structure provides localized structural reinforcement at the crystal lattice level, preventing crack propagation while allowing overall volume change during charging

Inventive Principle:

Principle #3Local quality

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 effectively reduces the confining pressure during charging, enhancing the structural integrity and cycle characteristics of all-solid-state batteries.

Implementation Method 1

an AlB2-type crystal structure, and absorbs Li between Si layers, have been found to be effective in suppressing an increase in confining pressure of an all-solid-state battery

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Data Source

PatentUS11043670B2All-solid-state battery including an anode having an anode layer containing MSi<sub>2</sub>

Publication Date: 2021.06.22 TOYOTA JIDOSHA KK

AI summary

Disclosed is an anode for all-solid-state batteries, which is, when used in an all-solid-state battery, configured to suppress an increase in the confining pressure of the battery during charge. The anode may be an anode wherein the anode is for use in all-solid-state batteries and comprises an anode layer, and wherein the anode layer contains MSi2 (where M is one element selected from the group consisting of Yb, Er, Tm and Lu) as an anode active material.