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 of particles during charge and discharge cycles, leading to shortened cycle life, low reversible capacity, and high irreversible capacity, as existing protective coatings are brittle and non-conductive, failing to provide adequate mechanical strength and lithium ion conductivity.
Innovation Solution
The development of composite particulates with anode active material particles dispersed in or encapsulated by a high-elasticity polymer matrix or shell, which provides a continuous phase for physical and ionic contact, offering high tensile strain and lithium ion conductivity, thereby preventing particle expansion-induced damage and enhancing cycling stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-capacity anode active materials (such as Si, Sn, Ge) are used to increase reversible capacity, then the battery capacity increases significantly, but severe pulverization occurs during charge-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, Sn, Ge, or their alloys) with a flexible polymer shell having high elastic recovery. The shell's elastic properties allow it to accommodate the significant volume expansion and contraction of the core material during lithium insertion and extraction cycles, preventing pulverization while maintaining structural integrity and enabling long cycle life
Solution Approach 2:
The patent creates a composite particle structure consisting of a core anode active material (providing high capacity) surrounded by a polymer shell (providing mechanical flexibility and protection). This composite structure combines the high capacity benefits of materials like Si/Sn/Ge with the mechanical resilience of elastic polymers, resolving the contradiction between capacity and cycle stability
2Strength
If conventional protective coatings (carbon, metal oxide, ceramic) are applied to prevent pulverization, then particle structural integrity improves, but the coatings are brittle and non-conductive, failing to provide adequate mechanical strength and lithium ion conductivity
Solution Approach 1:
The patent changes the fundamental parameter of protective coating material from conventional brittle inorganic materials (carbon, metal oxides, ceramics) to flexible organic polymers with high elastic recovery. This parameter change transforms the coating from rigid and non-conductive to flexible and ion-conductive, simultaneously providing mechanical protection and maintaining lithium ion transport capability
Solution Approach 2:
The patent replaces brittle conventional coatings with a flexible polymer shell that can dynamically respond to volume changes. The shell's flexibility allows it to stretch and compress with the core material during cycling, maintaining both mechanical integrity and lithium ion conductivity throughout the charge-discharge process
3Stability of the object's composition
If a protective coating is applied to prevent particle fragmentation, then particle integrity improves, but the coating materials are typically non-conductive, increasing internal resistance and reducing battery performance
Solution Approach 1:
The patent employs a flexible polymer shell that inherently possesses lithium ion conductivity, eliminating the need for additional conductive additives in the coating. The shell maintains particle integrity through its elastic properties while simultaneously providing ion transport pathways, thus protecting against fragmentation without increasing internal resistance
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 use of high-elasticity polymer-protected composite particulates significantly increases the cycle life and reversible capacity of lithium-ion batteries while reducing irreversible capacity and internal stress, enabling high-rate capacity and compatibility with common electrolytes.
Implementation Method 1
a high-elasticity polymer matrix or shell, which provides a continuous phase for physical and ionic contact, offering high tensile strain and lithium ion conductivity, thereby preventing particle expansion-induced damage
Implementation Method 2
the insertion and extraction of the lithium ions in and out of these particles. The expansion and contraction, and the resulting pulverization, of active material particles
Implementation Method 3
encapsulated by a shell of a high-elasticity polymer... preventing particle expansion-induced damage
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 (forming a continuous material phase) or encapsulated by a high-elasticity polymer shell, wherein the high-elasticity polymer (matrix or shell) has a fully recoverable 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 crosslinked network of chains from at least one polymer containing carboxylic and/or hydroxyl groups.