Elastic Polymer-Encapsulated Anode Particles for Lithium Batteries
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Solution Overview
Problem
Lithium-ion batteries face challenges with high-capacity anode active materials due to severe pulverization during charge and discharge cycles, leading to shortened cycle life, low reversible capacity, and high irreversible capacity, as existing protective coatings are brittle and fail to accommodate lithium ion conductivity.
Innovation Solution
Development of composite particulates with anode active material particles dispersed in or encapsulated by a high-elasticity polymer matrix or shell, providing a continuous phase for lithium ion conductivity and mechanical support, allowing for significant elastic deformation and preventing electrolyte interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-capacity anode active materials (such as Si, Ge, Sn, Pb, Sb, P, B, Al, Zn, Mg, Ag, Au) are used to increase lithium storage capacity, then the reversible capacity is improved, but severe pulverization occurs during charge and discharge cycles due to expansion and contraction, leading to shortened cycle life
Solution Approach 1:
The patent applies this principle by encapsulating high-capacity anode active material particles (Si, Ge, Sn, Pb, Sb, P, B, Al, Zn, Mg, Ag, or Au) with a flexible polymer shell having elastic deformation greater than 5%. This flexible shell accommodates the volume expansion and contraction of the core particles during lithium insertion and extraction, preventing pulverization and maintaining structural integrity throughout charge-discharge cycles, thus resolving the contradiction between high capacity and long cycle life
Solution Approach 2:
The patent creates a composite particle structure consisting of a core anode active material particle surrounded by a polymer shell matrix. This composite design combines the high lithium storage capacity of metals like Si and Sn with the mechanical flexibility and elasticity of the polymer coating, allowing the composite to simultaneously achieve high reversible capacity and excellent cycle stability by preventing the pulverization that would occur with pure metal particles
2Reliability
If protective coatings are applied to prevent pulverization, then cycle life is improved, but the coatings are brittle and fail to accommodate lithium ion conductivity
Solution Approach 1:
The patent changes the key parameter of the protective coating from brittle inorganic materials to flexible organic polymers with elastic deformation greater than 5%. This parameter change enables the coating to dynamically adapt to volume changes during cycling while maintaining lithium ion conductivity, resolving the contradiction between improved cycle life and maintained adaptability for ion transport
Solution Approach 2:
The patent replaces traditional brittle protective coatings with a flexible polymer shell that can elastically deform to accommodate the expanding and contracting core particles. This flexible shell maintains structural integrity throughout cycling while allowing lithium ion diffusion, thus improving cycle life without sacrificing lithium ion conductivity
3Strength
If the polymer matrix provides mechanical support and elasticity, then pulverization is prevented, but the polymer must maintain lithium ion conductivity
Solution Approach 1:
The patent creates a composite polymer matrix that combines mechanical strength for structural support with inherent lithium ion conductivity. The polymer matrix serves dual functions: providing elastic deformation capability to prevent pulverization while simultaneously serving as a conductive pathway for lithium ion transport, thus resolving the contradiction between mechanical support and ion 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 high-elasticity polymer matrix or shell enhances cycle stability, maintains lithium ion conductivity, and reduces capacity decay, achieving high reversible capacity and extended cycle life by preventing electrolyte interaction and accommodating volume expansion.
Implementation Method 1
a high-elasticity polymer matrix or shell having a recoverable tensile strain no less than 5%... allowing for significant elastic deformation
Implementation Method 2
a lithium ion conductivity no less than 10−8 S/cm... providing a continuous phase for lithium ion conductivity
Data Source
AI summary
A composite particulate for a lithium battery, wherein the composite particulate has a diameter from 10 nm to 50 μm and comprises one or more than one anode active material particles that are dispersed in a high-elasticity polymer matrix or encapsulated by a high-elasticity polymer shell, wherein the high-elasticity polymer matrix or shell has a recoverable elastic tensile strain no less than 5%, when measured without an additive or reinforcement dispersed therein, and a lithium ion conductivity no less than 10−8 S/cm at room temperature and wherein the high-elasticity polymer comprises a polymer derived from a monomer selected from the group consisting of vinyl sulfite, ethylene carbonate, methyl methacrylate, vinyl acetate, fluorinated monomers having unsaturation for polymerization, sulfones, sulfides, nitriles, sulfates, siloxanes, silanes, and combinations thereof.