Semi-Solid Electrode Design for Damage Tolerant Batteries
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Solution Overview
Problem
Conventional lithium-ion batteries with solid electrodes are prone to degradation and catastrophic failure upon mechanical or thermal damage, leading to reduced performance, energy density, and safety concerns, particularly in applications like hybrid and plug-in electric vehicles.
Innovation Solution
Development of electrochemical cells with semi-solid electrodes that can withstand mechanical and thermal abuse without significant degradation, featuring a semi-solid ion-storing redox composition with a thickness of at least 250 μm, allowing for flexible configurations and self-healing properties to maintain performance and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solid electrodes are used in lithium-ion batteries, then the manufacturing process is well-established and relatively simple, but the batteries are prone to degradation and catastrophic failure upon mechanical or thermal damage, leading to reduced performance and safety concerns
Solution Approach 1:
The patent changes the physical state parameter of the electrode from solid to semi-solid. This fundamental parameter change enables the electrode to tolerate mechanical damage (by deforming rather than fracturing) and thermal abuse (by maintaining structural integrity), directly improving reliability and damage tolerance while accepting increased manufacturing complexity
Solution Approach 2:
The patent employs composite material structure by combining active material particles with a binder matrix in a semi-solid configuration. This composite approach allows the electrode to exhibit both electrochemical functionality and enhanced mechanical tolerance, resolving the contradiction between reliability and ease of manufacture
2Quantity of substance
If electrode thickness is increased to improve energy density, then the capacity and energy density increase, but the ionic conductivity decreases and manufacturing becomes more difficult
Solution Approach 1:
By changing the electrode from solid to semi-solid state, the patent enables thicker electrode configurations (greater than 100 micrometers) to maintain adequate ionic conductivity. The semi-solid matrix provides ion transport pathways that remain effective even at increased thickness, allowing higher energy density without sacrificing ionic conductivity
Solution Approach 2:
The semi-solid electrode structure inherently provides a porous or channelled architecture that facilitates ion transport through the thickness of the electrode. This porous characteristic allows thicker electrodes to maintain good ionic conductivity, resolving the contradiction between quantity of active material and ion transport efficiency
3Strength
If binders are used in conventional electrode formulations to hold active materials together, then the electrode structure is maintained, but the tortuosity increases and ionic conductivity decreases
Solution Approach 1:
The patent changes the binder from a solid, tortuous matrix to a semi-solid formulation that provides structural integrity with reduced tortuosity. The semi-solid state allows for more direct ion transport pathways while still maintaining the mechanical strength needed to hold the electrode structure together, resolving the contradiction between strength and ionic conductivity
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
The semi-solid electrodes enhance energy density, charge capacity, and safety by maintaining operating voltage and temperature stability under mechanical deformation, high temperatures, and external short circuits, preventing thermal runaway and physical damage, thus improving the reliability and safety of lithium-ion batteries.
Implementation Method 1
At least one of the positive electrode and the negative electrode includes a semi-solid ion-storing redox composition
Implementation Method 2
an ion-permeable membrane separating the positive electrode and the negative electrode
Data Source
AI summary
Embodiments described herein relate generally to electrochemical cells having semi-solid electrodes that have damage tolerance, and in particular, are tolerant to physical damage due to short circuit, crushing, or overheating. In some embodiments, an electrochemical cell includes a positive electrode, a negative electrode and an ion-permeable membrane separating the positive electrode and the negative electrode. At least one of the positive electrode and the negative electrode can include a semi-solid ion-storing redox composition which has a thickness of at least about 250 μm. The electrochemical cell can have a first operating voltage in a first planar configuration and a second operating voltage in a second non-planar configuration such that the first operating voltage and the second operating voltage are substantially similar. In some embodiments, the electrochemical cell has a bend axis such that the electrochemical cell is bent about the bend axis in the second non-planar configuration.