Secondary Battery Solid Electrolyte Layer for Uniform Li-Ion Reaction
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Solution Overview
Problem
Secondary batteries with high nickel content electrodes face issues of uneven reaction distribution, leading to lithium precipitation, material deterioration, and manganese elution, which degrade cycle life and safety.
Innovation Solution
A secondary battery design incorporating a solid electrolyte layer with Li ion conductive oxide particles and a higher Mn abundance ratio on one surface compared to the other, promoting uniform reaction distribution and reducing side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If electrode thickness and density are increased to achieve high energy density, then energy density is improved, but reaction distribution becomes uneven leading to lithium precipitation and material deterioration
Solution Approach 1:
The patent applies local quality by creating a concentration gradient of Mn-containing substances within the electrolytic solution. The solution has a higher concentration of Mn-containing substances near the positive electrode and a lower concentration near the negative electrode. This localized variation in composition addresses the uneven reaction distribution in thick electrodes by providing better Mn suppression near the positive electrode while maintaining lithium ion conductivity near the negative electrode, thereby preventing lithium precipitation and material deterioration in high energy density cells.
Solution Approach 2:
The patent changes the concentration parameter of Mn-containing substances in the electrolytic solution to resolve the contradiction. By adjusting the concentration gradient of Mn-containing substances throughout the electrolyte, the patent optimizes both the suppression of Mn elution from the positive electrode and the prevention of lithium precipitation in the negative electrode, enabling high energy density while maintaining cycle life reliability.
2Quantity of substance
If high nickel content is used in positive electrode to improve energy density, then energy density is improved, but manganese elution increases causing excessive coating on negative electrode
Solution Approach 1:
The patent applies local quality by creating a non-uniform distribution of Mn-containing substances in the electrolytic solution, with higher concentration near the positive electrode. This localized high concentration effectively suppresses Mn elution from the high nickel positive electrode, preventing the formation of excessive coating on the negative electrode, while the lower concentration near the negative electrode maintains good lithium ion conductivity.
Solution Approach 2:
The Mn-containing substances in the electrolytic solution act as an intermediary that mediates between the high nickel positive electrode and the negative electrode. By introducing this intermediary substance with specific concentration gradient, the patent suppresses the harmful Mn elution from the positive electrode without directly modifying the electrode structures, thereby enabling high energy density while reducing manganese elution.
3Quantity of substance
If electrolytic solution permeation is difficult in thick dense electrodes, then electrode density is improved for high energy density, but lithium ion diffusion rate becomes rate-determining
Solution Approach 1:
The patent applies local quality by creating a spatial variation in electrolytic solution composition, with lower concentration of Mn-containing substances near the negative electrode. This localized low concentration region facilitates faster lithium ion diffusion to the negative electrode, addressing the rate-determining diffusion issue in thick dense electrodes, while the higher concentration regions elsewhere suppress Mn elution and maintain energy density.
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 cycle life and safety by improving lithium ion diffusion and reducing manganese elution and electrolyte decomposition, resulting in more stable battery performance.
Implementation Method 1
The solid electrolyte layer contains particles of a Li ion conductive oxide
Implementation Method 2
At least part of the second surface or the first and second surfaces includes a Mn-containing substance
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
According to one approach, a secondary battery (100) including a positive electrode (5), a negative electrode (3), an insulating layer, and a nonaqueous electrolyte is provided. The positive electrode (5) includes a positive electrode active material-containing layer (b) which contains a lithium nickel cobalt manganese composite oxide. The negative electrode (3) includes a negative electrode active material-containing layer (5b) that has a first surface (13) . The insulating layer includes a solid electrolyte layer (4b) that has a second surface (14) that is at least partly opposed to or partly in contact with the first surface (13) . The solid electrolyte layer contains a Li ion conductive oxide. At least part of the second surface (14) or the first and second surfaces (13, 14) includes a Mn-containing substance. An abundance ratio of Mn on the second surface (14) is higher than an abundance ratio of Mn on the first surface (13).