Polymer Binder for Lithium Battery Initial Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium batteries face challenges in achieving high initial efficiency due to increased initial irreversible capacitance caused by the large surface area of negative active materials, leading to low capacity and short lifetimes, especially at high temperatures and high discharge rates.
Innovation Solution
A novel polymer binder is developed, incorporating specific repeating units and alkali metal or ammonium groups, which forms conducting paths for lithium ions and creates an organic pre-solid electrolyte interface (pre-SEI) film to reduce side reactions between the electrode active material and electrolyte, thereby enhancing ion conductivity and initial efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the particle size of negative active materials is reduced to increase specific surface area, then the contact area between negative active material and electrolytic solution increases, but side reactions between electrolytic solution and negative active material increase, leading to increased initial irreversible capacitance and low initial efficiency
Solution Approach 1:
The patent introduces a polymer binder with specific functional groups (carboxyl, hydroxyl, or amine groups) as an intermediary substance between the negative active material and electrolytic solution. This binder forms a protective interface layer that mediates the interaction, allowing beneficial contact while blocking harmful side reactions. The functional groups in the binder coordinate with lithium ions and form a stable solid electrolyte interface (SEI) layer, preventing direct contact between the electrolyte and active material particles.
Solution Approach 2:
The patent changes the chemical and physical parameters of the binder material to optimize performance. Specifically, it uses polymers with controlled molecular weights (10,000-1,000,000 g/mol), specific functional group densities (0.1-10 mmol/g), and controlled water content (0.1-10 wt%). These parameter changes enable the binder to form a stable protective layer that reduces side reactions while maintaining good electrical contact and ion transport.
2Ease of manufacture
If conventional binders are used, then manufacturing is simple, but initial efficiency and capacity are limited due to insufficient protection against side reactions
Solution Approach 1:
The patent modifies the chemical composition parameters of conventional binders by introducing specific functional groups (carboxyl, hydroxyl, or amine groups) with controlled densities. The binder contains 0.1-10 mmol/g of these functional groups, which fundamentally changes its interaction with lithium ions and electrolyte. This parameter change maintains ease of manufacture while dramatically improving initial efficiency through enhanced protective film formation.
Solution Approach 2:
The patent creates a composite binder system that combines polymer matrices with specific functional groups. The composite structure integrates the mechanical properties of the polymer with the chemical reactivity of functional groups, achieving both easy processing and superior electrochemical performance. The binder acts as a composite material that simultaneously provides structural integrity and chemical protection.
3Loss of energy
If larger particle sizes are used to reduce side reactions, then initial efficiency improves, but contact area with electrolytic solution decreases, limiting capacity
Solution Approach 1:
The functional group-containing polymer binder serves as an intermediary that enables small particle sizes without increasing harmful side reactions. The binder molecules adsorb onto particle surfaces and extend into the electrolyte, creating a protective barrier that allows high surface area particles to function efficiently. This intermediary layer decouples the relationship between particle size and side reaction extent.
Solution Approach 2:
The patent applies local quality by concentrating functional groups at the particle-binder-electrolyte interface rather than uniformly distributing them throughout the bulk material. The functional groups are localized at the surface where they are most needed to prevent side reactions, while the bulk polymer provides mechanical binding. This localized functional distribution enables high surface area particles to maintain low side reaction rates.
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 novel polymer binder improves the initial efficiency and capacity of lithium batteries by reducing side reactions and forming a protective film, leading to better performance at high temperatures and high discharge rates.
Implementation Method 1
creates an organic pre-solid electrolyte interface (pre-SEI) film to reduce side reactions between the electrode active material and electrolyte
Implementation Method 2
forms conducting paths for lithium ions and creates an organic pre-solid electrolyte interface
Data Source
AI summary
A polymer including a first repeating unit represented by Formula 1, a polymer composition for a lithium battery including the polymer, an electrode for a lithium battery including the polymer composition, and a lithium battery including the electrode:wherein, in Formula 1, R, R′, A, A′, Y, and Y′ are as defined in the specification.