Polymer Adhesive Layer Separator for High-Voltage Lithium-Ion Battery Stability
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Solution Overview
Problem
Lithium-ion batteries face challenges with high-voltage cycle capacity retention due to structural disruption and side reactions, leading to gas production and thickness expansion, which impair their performance.
Innovation Solution
An electrochemical device with a positive electrode plate containing lithium transition metal oxide particles doped with elements like Mg and Al, coated with metal oxides, and a polymer adhesive layer in the separator to enhance adhesion and reduce reaction rates, thereby improving structural stability and suppressing gassing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the charge voltage limit of the positive active material is increased to achieve higher energy density, then the energy density is improved, but structural disruption and side reactions of the positive active material are aggravated
Solution Approach 1:
A polymer adhesive layer is introduced as an intermediary between the positive electrode plate and the separator. This adhesive layer acts as a mediator that suppresses gassing of the positive electrode plate while maintaining the high voltage operation necessary for high energy density. The adhesive layer has specific adhesion force (3-100 N/m) that enables it to effectively mediate the interaction between the electrode and separator, preventing structural disruption at high voltages.
Solution Approach 2:
The positive active material uses a composite structure with lithium transition metal oxide particles having specific composition (LiaCoxM1yM2zO2) that combines multiple elements to achieve both high voltage stability and high energy density. The composite material approach allows the positive electrode to operate at high voltages (4.3V or higher) without severe structural disruption, resolving the contradiction between energy density and structural stability.
2Use of energy by moving object
If the charge voltage limit is increased to improve energy density, then energy density is improved, but gas production increases causing thickness expansion
Solution Approach 1:
The polymer adhesive layer serves as an intermediary that suppresses gassing of the positive electrode plate during high-voltage operation. By positioning this adhesive layer between the positive electrode plate and separator, it mediates the gas production issue, preventing gas accumulation that would cause thickness expansion while allowing the battery to operate at high energy density voltages.
Solution Approach 2:
The polymer adhesive layer functions as a thin film structure that can accommodate and suppress gas generation without causing significant thickness expansion. This flexible thin film approach allows the battery to maintain compact dimensions while operating at high energy density, resolving the contradiction between energy density and volume control.
3Use of energy by moving object
If the charge voltage limit is increased to improve energy density, then energy density is improved, but cycle capacity retention performance deteriorates
Solution Approach 1:
The polymer adhesive layer acts as a protective intermediary that suppresses side reactions between the positive electrode plate and electrolyte during high-voltage cycling. This mediation effect preserves the cycle capacity retention performance even when the battery operates at high energy density voltages, resolving the contradiction between energy density and reliability.
Solution Approach 2:
The composite material structure of lithium transition metal oxide particles with specific composition (LiaCoxM1yM2zO2) provides inherent stability that maintains cycle capacity retention performance during high-voltage operation. The composite material design enables the positive electrode to sustain high energy density voltages over many cycles without severe degradation, simultaneously achieving high energy density and reliability.
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 solution effectively improves the high-voltage cycle capacity retention and structural stability of lithium-ion batteries by reducing Co dissolution and gas production, leading to enhanced performance and safety.
Implementation Method 1
a polymer adhesive layer that exerts an adhesive force of 3 N/m to 100 N/m on the positive electrode plate is disposed in the separator, thereby enhancing adhesion between the positive electrode plate and the separator
Implementation Method 2
Lithium-ion batteries are widely used in the field of consumer electronics by virtue of many advantages such as a high energy density, a long cycle life, a high nominal voltage, and a low self-discharge rate
Data Source
AI summary
An electrochemical device includes a positive electrode plate, a negative electrode plate, a separator, and an electrolytic solution. The positive electrode plate includes a positive active material having lithium transition metal oxide particles represented by a chemical formula LiaCoxM1yM2zO2, where 0.95≤a≤1.05, 0.05<x<1, 0≤y≤0.9, 0<z≤0.2, x+y+z=1, an M1 is one or two selected from the group consisting of Ni and Mn, and an M2 is at least one selected from the group consisting of Mg, Al, Ti, La, Y, and Zr. The separator includes a porous substrate and a polymer adhesive layer. The polymer adhesive layer is disposed between the porous substrate and the positive electrode plate. An adhesive force of the polymer adhesive layer between the positive electrode plate is 3 N/m to 100 N/m.