Layered Positive-Electrode Plate for High-Temperature Mn Release Control
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Solution Overview
Problem
Lithium manganese oxide (LMO) based positive-electrode materials in lithium-ion batteries suffer from metal release issues at high temperatures, leading to deteriorated high-temperature performance and cycling performance, and existing solutions using electrolytes result in excessive impedance and other performance issues.
Innovation Solution
A positive-electrode plate design featuring a first active substance layer with a lithium manganese-based material and a second active substance layer with a pH value of 10 to 12, which includes lithium-transition metal composite oxides or phosphates, to neutralize free acids in the electrolyte and mitigate metal release, while maintaining energy density and power performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If LMO is used as positive-electrode material to reduce costs, then cost is reduced, but metal release occurs at high temperature leading to deteriorated high-temperature performance
Solution Approach 1:
The positive electrode is segmented into two distinct active substance layers: a first layer containing LMO for cost-effectiveness and a second layer with high pH value materials for protecting against metal release. This segmentation allows each layer to perform its specific function independently, resolving the contradiction between cost and high-temperature performance.
Solution Approach 2:
The second active substance layer acts as an intermediary between the electrolyte and the LMO in the first layer. This intermediary layer neutralizes free acids in the electrolyte and prevents direct contact between HF and LMO, thereby preventing metal release while maintaining the cost benefits of LMO usage.
2Reliability
If conventional electrolyte solutions are used to improve high-temperature performance, then high-temperature performance is improved, but excessive impedance occurs and other performance deteriorates
Solution Approach 1:
The invention extracts the high-temperature protection function from the electrolyte and relocates it to the positive electrode structure. By placing high pH value materials in the second active substance layer, the patent removes the need for specialized electrolyte formulations that cause excessive impedance, thereby improving high-temperature performance without compromising electrical conductivity.
3Reliability
If Mn is released and deposited on negative-electrode surface at high temperature, then high-temperature cycling performance deteriorates, but using protective measures increases device complexity
Solution Approach 1:
The protective function is merged into the positive electrode structure itself by incorporating high pH value materials in the second active substance layer. This integrated approach prevents Mn release without requiring separate protective components or complex additional structures, thereby improving cycling performance while maintaining structural simplicity.
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 significantly reduces metal release and improves high-temperature performance of lithium-ion batteries without compromising power performance, enhancing energy density and cycle life.
Implementation Method 1
the second positive-electrode active substance layer with a high pH value is disposed on the surface of the first active substance layer to neutralize a part of free acids in the electrolyte so as to protect a lithium manganese-based oxide in the first active substance layer
Implementation Method 2
due to hydrofluoric (HF) corrosion in an electrolyte, Mn is plentifully released... the second positive-electrode active substance layer with a high pH value is disposed on the surface of the first active substance layer to neutralize a part of free acids in the electrolyte
Data Source
AI summary
This application provides a positive-electrode plate, including a current collector, and a first active substance layer and a second active substance layer that are sequentially disposed on a surface of the current collector. The first active substance layer includes a first positive-electrode active material, and the first positive-electrode active material includes at least one of a compound represented by Formula (I) Li1+x1Mna1M1-a1O2-y1Ay1 or a compound represented by Formula (II) Li1+x2Mna2N2-a2O4-y2By2. The second active substance layer includes a second positive-electrode active material having a pH value of from 10˜12. In this application, the active substance layer that includes high-pH positive-electrode active material is disposed outside the active substance layer that includes a lithium manganese-based positive-electrode active material, so as to make a layered electrode plate.