Conductive Net Encasing Silicon Alloy Anode
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Solution Overview
Problem
Lithium-ion batteries using graphite anodes suffer from low energy density due to low theoretical lithium storage capacity, while silicon-based anodes experience rapid capacity fade and poor durability caused by massive volume expansion during lithiation, leading to electrode delamination and increased internal resistance.
Innovation Solution
An anode design featuring an active material layer encased in a conductive net that allows for expansion and maintains electrical contact between alloying particles and carbon materials, preventing particle cracking and electrical isolation, with net openings permitting lithium ion and electron passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is added to active materials to increase theoretical lithium storage capacity, then energy density is improved, but rapid capacity fade and poor cycle life occur due to massive volume expansion
Solution Approach 1:
The patent employs a flexible buffer layer that can accommodate the massive volume expansion of silicon particles during lithiation. This buffer layer acts as a flexible shell that expands and contracts with the silicon, preventing particle cracking and maintaining structural integrity over multiple charge-discharge cycles, thereby improving cycle life while preserving high capacity
2Quantity of substance
If silicon active materials are used to increase lithium storage capacity, then energy density is improved, but electrode delamination and electrical isolation occur
Solution Approach 1:
The buffer layer serves as a flexible shell that maintains electrode structural stability during volume expansion. It prevents delamination by accommodating expansion forces and maintains electrical connectivity through its conductive nature, ensuring the electrode composition remains stable over multiple cycles
Solution Approach 2:
The patent creates a composite structure where silicon alloying particles are embedded in a carbon material matrix with an additional buffer layer. This composite approach combines the high capacity of silicon with the structural stability and conductivity of carbon materials, preventing electrical isolation while maintaining high lithium storage capacity
3Reliability
If graphite is used as anode material for stability and good cycle-life, then durability is improved, but low theoretical lithium storage capacity results in poor energy density
Solution Approach 1:
The patent creates a composite anode material combining graphite with silicon alloying particles and carbon materials. This composite structure leverages the stability and good cycle life of graphite while incorporating silicon to dramatically increase theoretical lithium storage capacity, achieving both durability and high energy density
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
Enhances energy density and cycle life by accommodating volume expansion, reducing capacity fade and internal resistance, and maintaining active material retention and conductivity.
Implementation Method 1
The conductive net also maintains electrical contact between the carbon material and the alloying particles during lithiation and delithiation of the alloying particles
Implementation Method 2
the conductive net having net openings sized to retain the alloying particles and the carbon material within the conductive net while allowing lithium ions and electrons to pass through
Data Source
AI summary
An anode for a lithium-ion battery includes a current collector, a separator and an active material comprising alloying particles and a carbon material. A conductive net of carbon material surrounds the active material on at least the side walls and a separator-facing surface, the conductive net having net openings sized to retain the alloying particles and the carbon material within the conductive net while allowing lithium ions and electrons to pass through. The conductive net also maintains electrical contact between the carbon material and the alloying particles during lithiation and delithiation of the alloying particles.