Silicon Composite Battery Anode with CNT Binder Against Particle Isolation
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Solution Overview
Problem
The use of large silicon particles in negative electrodes for non-aqueous electrolyte secondary batteries leads to isolation due to cracking and expansion, resulting in reduced cycle characteristics as the particles lose contact and capacity.
Innovation Solution
Incorporating carbon nanotubes (CNT) and an acrylic resin into the negative electrode material mixture, which includes a composite material with silicon particles dispersed in a silicate or carbon phase, to maintain the conductive path and reduce isolation, thereby enhancing cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If large silicon particles are used in the negative electrode, then the capacity is improved, but the cycle characteristics deteriorate due to particle isolation from cracking and expansion
Solution Approach 1:
The patent introduces a binder substance as an intermediary between silicon particles and the conductive network. This binder maintains contact between expanding silicon particles and the conductive path, preventing isolation while preserving high capacity. The binder acts as a flexible mediator that accommodates volume changes without breaking electrical connectivity.
Solution Approach 2:
The patent creates a composite structure combining silicon particles, conductive material, and binder in a integrated negative electrode formulation. This composite approach allows the simultaneous achievement of high capacity (from silicon) and good cycle characteristics (from the composite structure that prevents particle isolation).
2Quantity of substance
If silicon particles expand and contract during charge and discharge, then the capacity is maintained, but the particles become isolated due to cracking and gap formation
Solution Approach 1:
The patent employs a flexible binder network that surrounds and accommodates silicon particles during expansion and contraction. This flexible matrix maintains continuous contact with the particles through volume changes, preventing cracking-induced isolation while preserving electrical connectivity for capacity maintenance.
Solution Approach 2:
The patent creates a dynamic electrode structure where the binder and conductive network can adapt their configuration during charge-discharge cycles. This dynamic flexibility allows the structure to accommodate silicon particle volume changes without breaking contact, maintaining both capacity and particle connectivity throughout cycling.
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 combination of CNT and acrylic resin improves the cycle characteristics and maintains high capacity by securing the conductive path of isolated silicon particles, reducing side reactions and contact resistance, and suppressing the isolation of silicon particles during charge and discharge cycles.
Implementation Method 1
the combination of CNT and acrylic resin improves the cycle characteristics and maintains high capacity by securing the conductive path of isolated silicon particles
Implementation Method 2
the lithium ion conductive phase includes a silicate phase and/or a carbon phase
Data Source
AI summary
A negative electrode for a non-aqueous electrolyte secondary battery includes a negative electrode material mixture including a negative electrode active material capable of electrochemically absorbing and desorbing lithium ions, a carbon nanotube; and an acrylic resin. The negative electrode active material includes a composite material including a silicate phase, and silicon particles dispersed in the silicate phase, and the silicate phase includes at least one selected from the group consisting of alkali metal elements and Group 2 elements.