Negative Electrode Coating Roughness Control for Solid-State Batteries
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Solution Overview
Problem
Existing all-solid-state batteries face challenges in achieving high energy density and safety, particularly due to issues with uniformity and stability of the negative electrode coating layer, which can lead to increased chances of short circuits and reduced battery lifetime.
Innovation Solution
A negative electrode coating layer composed of a metal-carbon composite chemically bonded through sulfur, with controlled sulfur ion content and surface roughness, is introduced to enhance uniformity and stability, featuring a metal-carbon composite with sulfur ions between 1,000 ppm to 10,000 ppm and a root mean square roughness of 0.6 μm or less, along with controlled protrusion diameters and density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a negative electrode coating layer is formed for all-solid-state batteries, then energy density can be improved, but uniformity and stability of the coating layer may be compromised leading to short circuits and reduced battery lifetime
Solution Approach 1:
The invention controls specific parameters of the negative electrode coating layer including sulfur ion content (1,000-10,000 ppm), surface roughness (Sq ≤ 0.6 μm), and protrusion characteristics (diameter ≤ 20 μm, density ≤ 2 per 100 μm²) to achieve both high energy density and reliable battery operation, resolving the contradiction between energy density improvement and battery lifetime maintenance
Solution Approach 2:
The invention employs a composite coating layer containing metal-carbon composite particles with controlled sulfur content, combining multiple materials (metal particles, carbon particles, sulfur) to achieve both high energy density through lithium alloying capability and improved stability through the composite structure that prevents short circuits
2Quantity of substance
If the negative electrode coating layer is made thicker to increase energy density, then capacity improves, but surface uniformity and stability deteriorate increasing short circuit risk
Solution Approach 1:
The invention ensures uniform distribution of metal-carbon composite particles throughout the coating layer with controlled local characteristics including sulfur ion content (1,000-10,000 ppm) and surface protrusion density (≤ 2 per 100 μm²), allowing the coating to maintain high capacity while achieving surface uniformity that prevents short circuits
Solution Approach 2:
By controlling the surface roughness parameter (Sq ≤ 0.6 μm) and protrusion characteristics, the invention enables the coating layer to have sufficient thickness for high capacity while maintaining manufacturing precision and surface uniformity, resolving the contradiction between quantity and precision
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 results in improved battery lifetime and safety by reducing the risk of short circuits and enhancing the uniformity and stability of the electrode layer, thereby increasing the energy density and reducing internal resistance.
Implementation Method 1
a metal-carbon composite in which a metal and a carbon-based material are chemically bonded through sulfur
Data Source
AI summary
Provided are a negative electrode coating layer and an all-solid-state battery including the same, and, for example, a negative electrode coating layer for an all-solid-state battery, including a metal-carbon composite in which a metal and a carbon-based material are chemically bonded through sulfur, wherein a content of sulfur ions measured by negative ion analysis is about 1,000 ppm to about 10,000 ppm, and a root mean square roughness (Sq) of one surface is about 0.6 μm or less.