Negative Electrode Passivation Layer for Lithium Dendrite Suppression
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Solution Overview
Problem
Lithium-ion batteries face safety risks due to metal lithium plating and dendrite formation on the negative electrode surface during cycling, leading to irreversible deposition and decreased coulombic efficiency.
Innovation Solution
A negative electrode sheet with an active material layer and a passivation layer containing carboxymethyl cellulose and its metal salts is used, forming a uniform three-dimensional network to facilitate lithium ion migration and suppress dendrite growth, enhancing cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional negative electrode is used, then the battery can operate, but metal lithium plating and dendrite formation occur on the negative electrode surface after multiple cycles, causing safety risks and decreased coulombic efficiency
Solution Approach 1:
The patent introduces an ion resin layer as an intermediary substance between the negative electrode active material and the electrolyte. This ion resin layer acts as a mediator that facilitates lithium ion transport while preventing direct contact between the electrolyte and active material, thereby suppressing dendrite formation and improving cycle performance
Solution Approach 2:
The patent changes the physical and chemical parameters of the negative electrode interface by introducing the ion resin layer with specific properties (ion exchange capacity, cross-linking density, mechanical strength). These parameter changes create a stable interface that prevents lithium plating and dendrite growth while maintaining good ion conductivity
2Productivity
If the negative electrode active material undergoes volume change during cycling, then charge-discharge reactions occur, but this volume change causes interface reactions with the electrolyte and reduces battery stability
Solution Approach 1:
The ion resin layer forms a flexible protective film on the negative electrode surface that can accommodate volume changes of the active material during cycling. This thin film maintains interface stability while allowing the active material to expand and contract, preventing direct contact between the electrolyte and active material
Solution Approach 2:
The patent modifies the interface properties by introducing the ion resin layer with controlled cross-linking density and mechanical properties. These parameter changes enable the interface to remain stable during volume changes while maintaining good lithium ion transport
3Reliability
If no passivation layer is provided, then the structure is simple, but the negative electrode lacks protection against interface reactions and dendrite growth
Solution Approach 1:
The ion resin layer serves as an intermediary protective layer that provides dendrite suppression and interface protection. While this adds a layer to the electrode structure, the ion resin layer is thin and can be applied uniformly, minimizing the increase in overall complexity
Solution Approach 2:
The patent creates a composite structure by combining the negative electrode active material with the ion resin passivation layer. This composite structure provides both the electrochemical activity of the active material and the protective functions of the ion resin layer, achieving enhanced performance with moderate structural complexity
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 passivation layer effectively reduces interface reactions and volume changes, improving battery cycle life and safety by inhibiting lithium dendrite formation.
Implementation Method 1
cations exchangeable with lithium ions are present in the ion resin, thereby effectively driving rapid migration and uniform distribution of the lithium ions
Implementation Method 2
the ion resin further includes a large number of hydrogen bonds cross-linkable into a uniform and dense three-dimensional network structure which has a high anti-deformation capability
Implementation Method 3
effectively reducing an interface reaction between a negative electrode and an electrolyte solution during a cycle
Implementation Method 4
The passivation layer in the negative electrode sheet provided by the present application can be used as artificial SEI to suppress the generation and growth of a lithium dendrite
Data Source
AI summary
A positive electrode sheet and a preparation method therefor, a secondary battery, and an electric device. The negative electrode sheet includes a negative electrode current collector, an active material layer, and a passivation layer, where the active material layer is provided between the negative electrode current collector and the passivation layer; the active material layer includes a negative electrode active material, the passivation layer includes ion resin, and the ion resin includes one or more of carboxymethyl cellulose and a metal salt of carboxymethyl cellulose.