Carbon-Coated Negative Electrode for Uniform Lithium Deposition
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Solution Overview
Problem
Existing all-solid-state rechargeable batteries face issues with non-uniform lithium metal precipitation, leading to low initial charge/discharge efficiency and output characteristics due to volume expansion and lithium dendrite formation.
Innovation Solution
A negative electrode for all-solid-state rechargeable batteries featuring a carbon material with specific d002 values between 3.500 and 3.620, optimized for uniform lithium metal precipitation, combined with a lithiophilic metal for improved electrochemical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal is used as the negative electrode to increase energy density, then energy density is improved, but volume expansion and lithium dendrite formation occur reducing safety and reversible capacity
Solution Approach 1:
A carbon coating layer is introduced as an intermediary between the lithium metal and the electrolyte. This coating layer mediates the interaction by providing a stable interface that prevents direct contact between lithium metal and electrolyte, thereby preventing dendrite formation and volume expansion while maintaining high energy density
Solution Approach 2:
The invention changes the physical and chemical parameters of the negative electrode by coating lithium metal with carbon. This parameter change (adding carbon coating) transforms the surface properties to prevent harmful effects while preserving the high capacity benefits of lithium metal
2Reliability
If precipitation-type negative electrode is used to avoid lithium metal issues, then safety is improved, but initial charge/discharge efficiency and output characteristics deteriorate
Solution Approach 1:
The invention creates a composite negative electrode structure combining lithium metal and carbon coating layer. This composite material integrates the high capacity of lithium metal with the safety and stability of carbon, achieving both high initial charge/discharge efficiency and improved safety
Solution Approach 2:
The carbon coating is applied locally on the surface of lithium metal particles, creating different functional zones: the inner lithium metal provides high capacity while the outer carbon layer provides safety and stability. This local quality differentiation resolves the contradiction between performance and safety
3Ease of manufacture
If existing carbon materials are used in negative electrode coating layer, then manufacturing is simplified, but lithium metal precipitation uniformity and electrochemical characteristics are poor
Solution Approach 1:
The invention specifies precise parameter ranges for the carbon coating layer thickness (1-20 nm) and carbon content (5-50 wt%). By controlling these parameters, the invention achieves uniform lithium metal precipitation while maintaining ease of manufacture through conventional coating processes
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 solution enhances the initial charge/discharge efficiency and output characteristics by ensuring uniform lithium metal layer formation during charging, improving the electrochemical performance of the battery.
Implementation Method 1
the carbon material has a d 002 value of greater than or equal to 3.500 and less than or equal to 3.620 as measured by X-ray Diffraction
Implementation Method 2
induce precipitation of a good lithium metal layer of uniform thickness during charging
Data Source
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AI summary
Disclosed are a negative electrode for an all-solid-state rechargeable battery, and an all-solid-state rechargeable battery including the same, the negative electrode including a negative electrode current collector, and a negative electrode coating layer disposed on the negative electrode current collector and including a carbon material, wherein the carbon material has a d002 value of greater than or equal to 3.500 and less than or equal to 3.620 as measured by X-ray diffraction.