Silicon-Lithium Silicate Anode Composition for Crack-Resistant Cycling
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Solution Overview
Problem
Silicon-based negative electrode materials for lithium ion batteries suffer from significant expansion and contraction during charge and discharge cycles, leading to stress in the lithium silicate phase, which causes cracks and breaks in the composite particles, deteriorating charge-discharge cycle characteristics.
Innovation Solution
Incorporating a carbon material within the composite particles in a specific ratio (0.008 to 6% area ratio) and using a binder with a first resin (polyacrylic acid or its derivatives) in an amount of 2 mass% or less to enhance bonding and reduce stress, thereby suppressing the occurrence of cracks and breaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional lithium ion battery uses a liquid electrolyte, then ionic conductivity is maintained, but the battery suffers from leakage, flammability, and limited low-temperature performance
Solution Approach 1:
The patent changes the physical state parameter of the electrolyte from liquid to solid by using a polymer electrolyte matrix combined with lithium salt, fundamentally eliminating leakage and flammability issues while maintaining ionic conductivity through the solid-state polymer structure
Solution Approach 2:
The patent creates a composite electrolyte system by combining polymer materials (such as polyacrylonitrile, polyvinylidene fluoride, or carboxymethyl cellulose) with lithium salts (LiClO4, LiBF4, or LiPF6), forming a composite solid electrolyte that provides both structural integrity and ionic conduction pathways
2Object-affected harmful factors
If the battery uses solid polymer electrolyte, then leakage and flammability are eliminated, but manufacturing complexity increases due to multiple component requirements
Solution Approach 1:
The patent merges the electrolyte and separator functions into a single solid polymer electrolyte component, eliminating the need for separate liquid electrolyte filling and separator assembly steps, thereby reducing overall device complexity despite the advanced material composition
3Reliability
If the battery employs advanced polymer electrolyte materials, then safety improves, but manufacturing cost increases
Solution Approach 1:
The solid polymer electrolyte structure enables self-supporting battery construction without requiring additional containment systems for liquid electrolyte, eliminating the need for complex sealing and leakage prevention mechanisms, thereby reducing overall manufacturing costs despite advanced material usage
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 solution results in a lithium ion battery with improved charge-discharge cycle characteristics and high capacity by reducing stress and maintaining electrical communication between particles.
Implementation Method 1
The electrodes are charged and discharged electrochemically
Implementation Method 2
the electrolyte has good ion conductivity
Data Source
Figure 1
Figure 2
AI summary
A lithium ion battery including a negative electrode having a negative electrode active material layer that contains lithium silicate particles and a binder. The lithium silicate particles include composite particles including a lithium silicate phase and silicon particles dispersed in the lithium silicate phase, wherein a carbon material is present inside the composite particles, and an area ratio of the carbon material occupying a cross section of the composite particles is 0.008 to 6 %. The binder includes at least a first resin, wherein the first resin is at least one selected from the group consisting of polyacrylic acid, a polyacrylic acid salt, and their derivatives. The first resin is contained in an amount of 2 mass% or less in the negative electrode active material layer.