Patterned Porous Insulating Layer for Li-Ion Battery Electrode Safety
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Solution Overview
Problem
Conventional lithium ion secondary batteries face issues with reduced ion conduction and safety due to porous coating films, which increase internal resistance and fail to adequately prevent internal short circuits and nail penetration.
Innovation Solution
An electrode design featuring a porous insulating layer with an inorganic filler and resin binder applied in a specific pattern on the active material layer, allowing for both ion conductivity and insulation, reducing the risk of short circuit expansion and enhancing safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a porous coating film is formed throughout the surface of the active material layer, then the active material is protected from exfoliation, but ion conduction is reduced and internal resistance increases
Solution Approach 1:
The coating film is applied selectively to specific regions (first regions) of the active material layer surface rather than uniformly across the entire surface. This local application strategy protects active material in areas where coating provides benefit while leaving other areas (second regions) uncovered to maintain ion conduction pathways, thus resolving the contradiction between protection and ion transport.
2Stability of the object's composition
If a porous coating film is formed throughout the surface of the active material layer, then the active material is protected from exfoliation, but the battery capacity and charge-discharge characteristics decrease
Solution Approach 1:
By applying the coating film only to specific first regions rather than the entire surface, the invention maintains battery capacity and charge-discharge characteristics while still providing protection where needed. The uncovered second regions ensure sufficient ion conduction for high productivity.
3Reliability
If the separator is made of polyethylene or polypropylene, then it provides electrical insulation, but it shrinks at high temperatures causing increased short circuit area and reduced safety
Solution Approach 1:
The invention uses a composite coating film comprising both organic resin binder and inorganic filler particles. The inorganic filler provides heat resistance and dimensional stability at high temperatures, while the resin binder provides adhesion and flexibility. This composite structure resolves the contradiction between electrical insulation and heat resistance.
Solution Approach 2:
The coating film is designed with a porous structure containing inorganic filler particles, which allows ion conduction while providing thermal stability. The porous structure prevents the film from shrinking at high temperatures, maintaining safety against short circuits while enabling electrical insulation function.
4Stability of the object's composition
If a porous coating film containing solid microparticles and resin binder is formed, then exfoliation of active material is reduced, but safety against internal short circuit and nail penetration is not secured
Solution Approach 1:
The composite coating film with inorganic filler provides both active material stability and enhanced safety against short circuits. The inorganic particles create a physically robust barrier that prevents dendrite penetration and short circuits, while the porous structure maintains ion conduction.
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 electrode design improves safety, charge-discharge characteristics, and heat resistance by maintaining high ion conductivity while preventing excessive heat generation during internal short circuits or nail penetration.
Implementation Method 1
ions pass through the pores of a porous coating film which is formed by applying a mixture of a resin binder and solid microparticles onto an electrode plate
Implementation Method 2
separators made of these materials shrink easily at high temperatures... the porous insulating layer comprises an inorganic filler and a resin binder
Data Source
AI summary
Disclosed is an electrode for lithium ion secondary batteries which includes an active material layer containing active material particles and a porous insulating layer formed on the surface of the active material layer. The porous insulating layer includes an inorganic filler and a resin binder, and the surface of the active material layer has a first region on which the porous insulating layer is formed, and a second region on which the porous insulating layer is not formed. By using such an electrode, a lithium ion secondary battery can have a high capacity, excellent characteristics and improved safety.