Solid Electrolyte Compression to Deflect Battery Dendrites

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Solution Overview

Problem

Conventional Li ion batteries face limitations such as low energy density, flammability, and poor cycle life due to metal dendrites piercing the solid electrolyte, leading to short-circuits.

Innovation Solution

Implementing a compressive stress state in the solid electrolyte to suppress and deflect dendrite growth by applying external mechanical loads, residual stresses, or thermal expansion mismatches, ensuring stress components are orthogonal to the electric field direction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a stack pressure is applied to increase critical current densities and improve uniformity of metal deposition, then the uniformity of metal deposition is improved, but dendrite growth towards the cathode is promoted

Engineering Contradiction:

Improveuniformity of metal depositionVSAvoiddendrite growth suppression

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent changes the orientation and direction of applied stress from conventional stack pressure (parallel to electric field) to orthogonal compressive stress (perpendicular to electric field). This parameter change allows the stress to suppress dendrite growth without promoting it, resolving the contradiction between deposition uniformity and dendrite suppression

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Instead of applying pressure in the conventional direction (stack pressure parallel to electrodes), the patent applies compressive stress in the orthogonal direction (perpendicular to electric field lines). This inversion of the stress application direction eliminates the harmful effect of promoting dendrite growth while maintaining the beneficial effects on deposition uniformity

Inventive Principle:

Principle #13The other way round (Inversion)

2Volume of moving object

If the solid electrolyte is made thinner to reduce cell volume, then the energy density is improved, but the risk of dendrite penetration increases

Engineering Contradiction:

Improvecell volumeVSAvoiddendrite penetration resistance

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent changes the stress state parameter from conventional tensile or neutral stress to compressive stress oriented orthogonal to the electric field. This parameter change enables thin electrolyte membranes to resist dendrite penetration through compressive forces that deflect dendrites away from the cathode, maintaining safety while reducing cell volume

Inventive Principle:

Principle #35Parameter changes

3Reliability

If conventional Li ion batteries use liquid or gel electrolytes to achieve good ionic conductivity, then the ionic conductivity is improved, but flammability and safety issues arise

Engineering Contradiction:

Improveionic conductivityVSAvoidflammability

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the physical state parameter of the electrolyte from liquid or gel phase to solid phase. This phase change eliminates flammability while maintaining ionic conductivity through the solid electrolyte material, and the orthogonal compressive stress further enhances safety by suppressing dendrite growth that could cause short circuits

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

Extends the life of solid-state batteries by forcing dendrites to follow a longer, more tortuous path, reducing the risk of short circuits and enhancing safety.

Implementation Method 1

a solid electrolyte in a compressive stress state to suppress and/or deflect the growth of metal dendrites

Methodology Applied

Scientific EffectCompressive stress: Compression

Implementation Method 2

the compressive stress includes at least one stress component oriented along a first direction that is substantially orthogonal to a direction of the electric field in the portion of the solid electrolyte

Methodology Applied

Scientific EffectStress deflection: Deformation

Implementation Method 3

the compressive stress is caused by a thermal expansion mismatch between the cathode and the solid electrolyte

Methodology Applied

Scientific EffectThermal expansion mismatch: Thermal Expansion

Data Source

PatentUS20250349944A1Systems and methods for controlling dendrite propagation in solid-state electrochemical cells

Publication Date: 2025.11.13 MASSACHUSETTS INST OF TECH

AI summary

A solid-state electrochemical cell includes a solid electrolyte where at least a portion of the electrolyte is in a compressive stress state. The compressive stress state includes at least one stress component that is orthogonal to the preferred direction of dendrite growth, which may correspond to the direction of an electric field. If the magnitude of the stress component is sufficiently large (e.g., greater than 50 MPa), then the growth of a dendrite passing through that portion of the electrolyte may be suppressed or deflected towards the direction of the applied stress component. In this manner, a dendrite may be deflected away from a cathode, thus prolonging the life of the cell. The compressive stress state may be generated by applying an external mechanical load to the cell and/or generating a residual stress in the cell during manufacture or assembly.