Citric Acid Copolymer Coating for Lithium Metal Anode Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium metal batteries face safety issues due to uncontrollable growth of lithium dendrites caused by irregular deposition of lithium ions, which is not effectively addressed by existing protective films with weak mechanical strength and incomplete coverage.
Innovation Solution
A negative electrode plate with a polymer protective film made of citric acid copolymer, having a number-average molecular weight of 10,000 to 1,000,000, which forms a high-strength, high-elongation film with carboxyl and hydroxyl groups to inhibit lithium dendrite growth and enhance electrolyte holding capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective film is formed on the lithium metal surface using functional additives, then the lithium metal surface is enhanced, but the film has weak mechanical strength and does not fully cover the lithium metal
Solution Approach 1:
The patent changes the molecular weight parameter of the polymer protective film to 10,000 to 1,000,000, which is significantly higher than conventional films. This parameter change results in a film with both high mechanical strength and high elongation, resolving the contradiction between reliability enhancement and mechanical strength deficiency
Solution Approach 2:
The patent uses citric acid copolymer as the protective film material, which forms a composite structure with high molecular weight chains. This composite material approach creates a film that simultaneously achieves full coverage of lithium metal surface and provides exceptional mechanical strength and elongation properties
2Reliability
If conventional protective films are used, then some surface protection is provided, but they cannot prevent severe and continuous reorganization of SEI films caused by morphology change of lithium metal
Solution Approach 1:
The patent changes the molecular weight parameter to 10,000 to 1,000,000, creating a protective film with high elongation capability. This allows the film to dynamically adapt to morphology changes of lithium metal during cycling, preventing severe SEI film reorganization and maintaining long-term cycle performance
Solution Approach 2:
The high molecular weight polymer film exhibits dynamic flexibility that allows it to accommodate the continuous morphology changes of lithium metal during deposition and dissolution. The film can stretch and conform to changing surfaces, maintaining continuous protection and preventing SEI film breakdown throughout cycling
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 citric acid copolymer film significantly improves the cycle stability and safety of lithium metal batteries by slowing down or inhibiting lithium dendrite growth, reducing side reactions, and enhancing initial charge and discharge efficiency.
Implementation Method 1
a structure of the citric acid copolymer contains a large number of carboxyl groups and hydroxyl groups that can react with lithium metal
Implementation Method 2
high electrolyte holding capacity
Data Source
AI summary
This application provides a negative electrode plate, a lithium metal battery, and an apparatus including the lithium metal battery. The negative electrode plate includes a negative electrode current collector and a lithium-metal negative electrode disposed on at least one surface of the negative electrode current collector, where a polymer protective film is disposed on a surface of the lithium-metal negative electrode away from the negative electrode current collector, the polymer protective film includes a citric acid copolymer, and a number-average molecular weight Mn of the citric acid copolymer is 10,000 to 1,000,000. In this application, a polymer protective film with high tensile strength, high puncture strength, high elongation, and high electrolyte holding capacity may be formed on the surface of the lithium-metal negative electrode in the negative electrode plate.