Water-Soluble Polymer Coated Anode for Lithium Battery Capacity
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Solution Overview
Problem
Lithium secondary batteries face limitations in initial efficiency and reversible capacity due to the use of carbon anode active materials, which can lead to short cycle life and increased irreversible capacity, especially with materials like silicon and tin that experience volume changes during charge and discharge, causing conductivity issues and delamination.
Innovation Solution
A composite anode active material is developed by coating a water-soluble polymer on the surface of the anode active material, combined with a binder such as polyimide, polyamideimide, or polyetherimide, to form a composite anode for lithium secondary batteries, which reduces side reactions with the electrolyte and enhances mechanical strength, thereby improving initial efficiency and reversible capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metal or intermetallic compound anode active material is used to increase capacity and energy density, then the battery capacity and energy density are improved, but the cycle life becomes shorter due to volume changes causing conductivity decrease and delamination
Solution Approach 1:
The patent uses composite materials by combining metal or intermetallic compound anode active material with carbon material. The carbon material forms a coating layer on the metal particles, creating a composite structure that maintains the high capacity of metal materials while providing the structural stability and conductivity of carbon, thereby improving cycle life
Solution Approach 2:
The carbon material forms a thin film coating on the surface of metal particles. This carbon shell acts as a protective layer that accommodates volume changes during charge-discharge cycles, prevents direct contact between electrolyte and metal surface, and maintains electrical conductivity, thus extending cycle life while preserving high capacity
2Quantity of substance
If active material with small particle diameter or large specific surface area is used to increase capacity, then the energy density is improved, but the initial efficiency decreases due to increased side reactions with electrolyte
Solution Approach 1:
A carbon coating layer is formed on the surface of metal particles with small diameter or large specific surface area. This carbon shell reduces the direct contact area between the reactive metal surface and electrolyte, suppressing side reactions and forming a stable solid electrolyte interface, thereby improving initial efficiency while maintaining high energy density
Solution Approach 2:
The carbon material acts as an intermediary layer between the metal anode active material and the electrolyte. This intermediate carbon coating prevents direct harmful interactions between electrolyte and metal surface, reducing initial irreversible capacity loss while allowing lithium ion transport, thus improving initial efficiency
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 composite anode active material effectively prevents electrode degradation from volume changes, increases initial efficiency, enhances reversible capacity, and improves energy density by forming a protective organic pre-solid electrolyte interface, leading to improved performance and extended cycle life of lithium secondary batteries.
Implementation Method 1
forming a protective organic pre-solid electrolyte interface
Implementation Method 2
a binder disposed on the composite anode active material, the binder including one or more selected from a polyimide, a polyamideimide, a polyamide, and a polyetherimide
Data Source
AI summary
An anode for a lithium secondary battery including: a composite anode active material including an anode active material, and a water-soluble polymer disposed on a surface of the anode active material; and a binder disposed on the composite anode active material, the binder including one or more selected from a polyimide, a polyamideimide, a polyamide, and a polyetherimide.