Asymmetric Electrode Laminate for Lithium Battery Capacity Balance
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Solution Overview
Problem
Lithium secondary batteries face issues with irreversible capacity, reduced discharge capacity, and cycle deterioration due to the formation of a passivating layer on carbon-based negative electrodes, and challenges in achieving high energy density with spinel-type manganese-based positive electrodes.
Innovation Solution
An electrode laminate with a larger positive electrode material coating area than negative electrode material coating area, using lithium nickel manganese oxide as the positive electrode and lithium titanium oxide as the negative electrode, and incorporating porous polymer films for optimal arrangement and capacity balance, along with a separation sheet for structural support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon-based material is used as negative electrode coating layer, then cost is reduced, but irreversible capacity occurs and discharge capacity is reduced
Solution Approach 1:
The patent changes the material parameter of the negative electrode from carbon-based material to lithium titanium oxide (LTO), which has different electrochemical properties including higher oxidation/reduction potential (about 1.5 V vs. Li/Li+) and structural stability that prevents irreversible capacity loss while maintaining good cycle characteristics
Solution Approach 2:
The patent creates a composite electrode structure by combining LTO negative electrode with spinel-type manganese-based positive electrode materials, achieving synergistic effects that improve overall battery reliability and energy density
2Reliability
If spinel type manganese-based material is used as positive electrode coating layer, then cost is reduced, but energy density is reduced
Solution Approach 1:
The patent modifies the spinel-type manganese-based material by replacing some Mn with Ni to form Li(Ni-Co-Mn)O2 or similar compositions, which increases the operating potential to 5V level and improves energy density while maintaining the structural stability and cycle characteristics of the spinel structure
Solution Approach 2:
The patent develops composite positive electrode materials combining spinel-type manganese-based materials with nickel and cobalt components, achieving a balance between cost, cycle stability, and enhanced energy density
3Use of energy by moving object
If positive electrode material coating area is increased relative to negative electrode, then energy density is improved, but capacity imbalance occurs
Solution Approach 1:
The patent optimizes the coating area ratio between positive and negative electrodes, specifically designing the negative electrode coating area to be 90-110% of the positive electrode coating area, achieving optimal capacity balance (N/P ratio) that prevents lithium plating while maximizing energy density
Solution Approach 2:
The patent deliberately creates an asymmetric electrode configuration where the negative electrode (LTO) has slightly different coating area compared to the positive electrode, compensating for the inherently different capacities of LTO versus spinel-type manganese-based materials and achieving optimal overall battery performance
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
This configuration maximizes the life span and energy performance of the battery by preventing lithium plating and electrolyte decomposition, while simplifying the manufacturing process and reducing costs by eliminating the need for additional devices or processes.
Implementation Method 1
porous polymer films, each interposed between a positive electrode and a negative electrode
Implementation Method 2
a carbon material have a low oxidation/reduction potential of about 0.1 V with respect to potential of Li/Li+
Implementation Method 3
a lithium salt-containing non-aqueous electrolyte
Data Source
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AI summary
Disclosed herein is an electrode laminate including a positive electrode having a positive electrode material coating layer formed on a positive electrode current collector, a negative electrode having a negative electrode material coating layer formed on a negative electrode current collector, and a porous polymer film interposed between the positive electrode and the negative electrode, wherein the positive electrode, the negative electrodes, and the porous polymer films are laminated in a height direction on the basis of a plane such that the negative electrodes constitute outermost electrodes of the electrode laminate, and the positive electrode material coating layer has a larger coating area than the negative electrode material coating layer.