Active Material Ball Electrode Structure for Silicon Volume Change

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Solution Overview

Problem

Lithium ion batteries face safety concerns due to the flammability and volatility of liquid electrolytes, and solid electrolytes have low ionic conductivity and large charge transfer resistance, while negative electrode materials like silicon suffer from significant volume change during charging and discharging, limiting energy density and electrode performance.

Innovation Solution

An active material ball electrode layer structure is developed, using a dual-type electrolyte system with different characteristics inside and outside the active material balls to address charge transfer resistance and volume change issues, comprising a first mixed electrolyte with higher deformation for volume stability and a second mixed electrolyte with lesser deformation for expansion resistance, improving ion conduction and safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If liquid electrolyte is used, then ionic conductivity and charge transfer are improved, but safety and stability deteriorate due to flammability and volatility

Engineering Contradiction:

Improveionic conductivityVSAvoidflammability and volatility

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by using different types of electrolytes in different locations: liquid electrolyte is used inside the active material balls where high ionic conductivity and charge transfer are needed, while solid electrolyte is used outside the balls where safety and stability are priorities. This spatial differentiation allows each electrolyte type to perform its optimal function in the appropriate location.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If solid electrolyte is used, then safety and stability are improved, but charge transfer resistance and contact area deteriorate

Engineering Contradiction:

Improvesafety and stabilityVSAvoidcharge transfer resistance

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

Inventive Principle:

Principle #3Local quality

3Quantity of substance

If silicon is used as negative electrode material, then volumetric capacity is improved, but volume change and void formation deteriorate

Engineering Contradiction:

Improvevolumetric capacityVSAvoidvolume change

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent applies the nested doll principle by placing liquid electrolyte inside the active material balls, nesting the electrolyte within the silicon-based active material structure. This internal electrolyte reservoir maintains contact with the active material during volume expansion and contraction, preventing void formation and maintaining electrical connectivity throughout the charge-discharge cycles.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent applies beforehand cushioning by pre-filling the active material balls with liquid electrolyte before assembly. This internal electrolyte acts as a cushion that accommodates the volume changes of silicon during lithiation and delithiation, maintaining physical contact and preventing the formation of voids that would occur with external electrolyte only.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 enhances ion conduction, reduces safety risks, and mitigates volume changes in active materials, leading to improved electrical capacity and thermal stability in lithium ion batteries.

Implementation Method 1

The first mixed electrolyte, mainly composed of an electrolyte with relatively greater deformation

Methodology Applied

Scientific EffectDeformation: Deformation

Implementation Method 2

the second mixed electrolyte, mainly composed of an electrolyte with relatively lesser deformation, to be disposed outside the active material balls

Methodology Applied

Scientific EffectExpansion resistance:

Implementation Method 3

The ionic conductivity of the solid electrolytes are similar to the ionic conductivity of the liquid electrolytes

Methodology Applied

Scientific EffectIon conduction:

Data Source

PatentEP3772764B1Active material ball electrode layer structure

Publication Date: 2024.09.04 PROLOGIUM TECHNOLOGY CO LTD

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AI summary

The invention discloses an active material ball electrode layer structure, which mainly includes the active material balls made of the active material particles, a first mixed electrolyte located inside the active material balls, and a second mixed electrolyte located outside the active material balls. The first mixed electrolyte is mainly made of the deformable electrolyte. The second mixed electrolyte is mainly made of the electrolyte with relatively lesser deformation than the deformable electrolyte of the first mixed electrolyte. The invention utilizes the first mixed electrolyte to effectively active material ball reduce the derived problems of the volume change of the active materials. Moreover, the different configuration of the first mixed electrolyte and the second mixed electrolyte inside and outside the active material balls is utilized to reduce the charge transfer resistance. Also, the expansion resistance is provided for the active material balls.