Lithium Metal Anode Polymer Coating for Dendrite-Free Deposition
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Solution Overview
Problem
Lithium metal secondary batteries suffer from rapid cycle life decline, short circuits, and severe safety risks due to lithium dendrite formation and electrolyte consumption.
Innovation Solution
A lithium metal negative electrode material with a dense and uniform polymer layer containing a fluorinated aliphatic chain and flexible side chains is applied, which inhibits electrolyte and lithium contact, promotes uniform lithium deposition, and enhances adhesion and flexibility to prevent dendrite formation and volume expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective layer is added to inhibit lithium dendrite formation, then battery safety and cycle life are improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies preliminary action by pre-coating the lithium metal surface with a polymer layer containing fluorinated aliphatic chains before battery assembly. This protective layer is formed in advance through in-situ polymerization of cyanoacrylate monomers on the lithium surface, creating a dendrite-inhibiting interface before any harmful dendrite growth can occur. The layer is prepared beforehand and then integrated into the battery structure, avoiding the need for complex post-assembly modifications.
Solution Approach 2:
The patent uses an intermediary approach by introducing a polymer coating as a mediating layer between the lithium metal and the electrolyte. This intermediary layer contains fluorinated aliphatic chains that act as a buffer zone, preventing direct contact between lithium and electrolyte while allowing lithium ion transport. The intermediary layer resolves the contradiction by providing protection without requiring fundamental changes to the battery's core structure.
2Strength
If the polymer layer is made denser to improve adhesion, then interface impedance increases, but if made more flexible to adapt to volume expansion, then adhesion strength decreases
Solution Approach 1:
The patent applies local quality by creating a polymer layer with spatially varying properties. The polymer coating contains fluorinated aliphatic chains distributed throughout its structure, providing localized regions of strong adhesion to lithium metal. Simultaneously, the polymer matrix maintains flexibility in other regions to accommodate volume expansion during cycling. This local differentiation allows the single layer to satisfy both adhesion and flexibility requirements.
Solution Approach 2:
The patent uses composite materials by combining fluorinated aliphatic chains within a polymer matrix structure. The fluorinated chains provide strong bonding to lithium metal surfaces, while the polymer backbone (containing EO blocks and flexible side chains) provides flexibility and ion conductivity. This composite structure resolves the contradiction between adhesion strength and flexibility by integrating materials with complementary properties into a unified coating.
3Use of energy by moving object
If lithium metal is used to achieve high energy density, then battery capacity increases, but lithium dendrite formation causes short circuits and safety risks
Solution Approach 1:
The patent converts the harmful effect of lithium dendrite formation into a beneficial outcome by using the fluorinated polymer layer to guide lithium ion deposition. Instead of allowing random dendrite growth, the fluorinated aliphatic chains in the polymer coating create uniform nucleation sites that promote homogeneous lithium deposition. The potential harm of dendrite formation is transformed into controlled, uniform plating that enhances battery performance and safety.
Solution Approach 2:
The patent applies parameter changes by modifying the surface properties of lithium metal through polymer coating. The fluorinated polymer layer changes the interfacial parameters between lithium and electrolyte, including surface energy, wettability, and ion transport characteristics. These parameter modifications prevent dendrite formation while maintaining high lithium ion conductivity, allowing the system to achieve both high energy density and improved safety.
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 polymer layer effectively prolongs battery cycle life, reduces interface impedance, and enhances energy and power density while ensuring safety by inhibiting dendrite formation and electrolyte consumption.
Implementation Method 1
The dense and uniform polymer layer can alternatively be swollen by the electrolyte solution, and can provide good ionic conductivity after being swollen
Data Source
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AI summary
The present application relates to a lithium metal negative electrode material, a negative electrode sheet, a lithium metal secondary battery, an electric device, a preparation method, and use. The lithium metal negative electrode material includes lithium-containing metal and a polymer Poly bonded to lithium metal in the lithium-containing metal, the polymer Poly has a linear carbon chain, and a first side chain and a second side chain that are grafted to a side group of the linear carbon chain, the first side chain contains a fluorinated aliphatic chain Rf, and the second side chain contains an EO block.