Lithium Metal Negative Electrode Structure Against Buckling
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Solution Overview
Problem
Lithium secondary batteries face issues with electrode buckling and rupture due to the brittleness of copper current collectors at low negative electrode potentials, leading to deteriorated cycle characteristics.
Innovation Solution
A lithium secondary battery design featuring a negative electrode with a resin film laminated with a lithium metal layer, which provides flexibility and reduces stress, replacing traditional copper current collectors to prevent buckling and rupture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper is used as the current collector in lithium secondary batteries, then effective current collection is achieved, but the copper becomes brittle at low negative electrode potentials causing electrode buckling and rupture
Solution Approach 1:
The patent uses a composite current collector structure consisting of a copper foil base layer combined with a resin film layer. The copper foil provides excellent electrical conductivity and current collection, while the resin film provides flexibility and prevents brittleness. This composite structure resolves the contradiction by combining materials with complementary properties to achieve both effective current collection and resistance to buckling/rupture during cycling.
Solution Approach 2:
The patent applies a resin film coating on the copper current collector to provide flexibility. The resin film acts as a protective layer that prevents the copper from becoming brittle and cracking during volume changes associated with lithium deposition and dissolution. This flexible film structure maintains electrode integrity while allowing the copper to perform its current collection function.
2Quantity of substance
If lithium metal deposits and dissolves at the negative electrode during charging and discharging, then high capacity is achieved, but significant volume changes cause electrode buckling and breakage
Solution Approach 1:
The resin film coating on the copper current collector acts as a flexible buffer that accommodates the significant volume changes occurring during lithium deposition and dissolution. This flexible layer prevents the electrode from buckling or breaking while allowing the lithium metal to deposit and dissolve, thereby maintaining both high capacity and electrode structural stability during cycling.
Solution Approach 2:
The composite structure of copper foil combined with resin film provides both the electrical conductivity needed for high lithium capacity and the mechanical flexibility needed to handle volume changes. The copper layer enables efficient lithium ion insertion/extraction while the resin film maintains structural integrity during the associated volume expansion and contraction.
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 resin film-laminated lithium metal layer configuration enhances the battery's cycle characteristics by suppressing deterioration and increasing energy density while maintaining effective current collection.
Implementation Method 1
the negative electrode includes a resin film, and a lithium metal layer laminated with the resin film... copper becomes brittle in the state where the negative electrode potential is low. Since the embrittlement of copper accelerates the occurrence of electrode buckling, electrode rupture, etc.
Implementation Method 2
lithium metal deposits at the negative electrode during charging, and the lithium metal dissolves in the nonaqueous electrolyte during discharging, to release lithium ions
Implementation Method 3
a nonaqueous electrolyte having lithium-ion conductivity
Data Source
AI summary
A lithium secondary battery including a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and a nonaqueous electrolyte having lithium-ion conductivity. At the negative electrode, lithium metal deposits during charging, and the lithium metal dissolves during discharging. The negative electrode includes a resin film, and a lithium metal layer laminated with the resin film.