Core-Shell Positive Electrode Plate for Manganese Dissolution Control
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Solution Overview
Problem
Existing secondary batteries face issues with manganese dissolution during charge/discharge processes, leading to increased impedance, reduced lithium ion migration, and compromised safety and cycling performance due to interfacial reactions and electrolyte consumption.
Innovation Solution
A positive electrode active material with a core-shell structure is developed, comprising an inner core of Li1+xMn1−yAyP1−zRzO4 and coating layers of pyrophosphate and phosphate, along with a conductive undercoat layer to enhance bonding strength and inhibit manganese dissolution, promote lithium ion migration, and improve electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional positive electrode plate structure is used, then the battery can operate, but manganese dissolution occurs during charge/discharge leading to increased impedance and reduced performance
Solution Approach 1:
A conductive undercoat layer comprising a polymer, water-based binder, and conductive agent is introduced as an intermediary between the positive electrode current collector and the positive electrode film layer. This undercoat layer acts as a protective barrier that inhibits manganese dissolution into the electrolyte while maintaining electrical conductivity, thereby resolving the contradiction between reliability and harmful factors generated by the electrode materials.
Solution Approach 2:
The positive electrode active material is designed with a core-shell structure where the inner core contains Li1+xMn1−yAyP1−zRzO4 and the shell comprises coating layers including pyrophosphate and phosphate. This composite material structure protects the manganese-containing core from dissolving into the electrolyte while maintaining lithium ion conductivity, thus improving cycling performance by preventing manganese dissolution.
2Strength
If the positive electrode active material is coated directly on the current collector, then the structure is simple, but bonding strength is insufficient and film peeling occurs
Solution Approach 1:
The conductive undercoat layer serves as an intermediary bonding layer between the current collector and the positive electrode film layer. This undercoat layer enhances adhesion and prevents film peeling during battery operation, resolving the contradiction between strength and device complexity by adding a functional intermediate layer.
3Power
If the positive electrode film layer is applied directly without undercoat, then the electrode structure is simpler, but electrical conductivity at the interface is reduced
Solution Approach 1:
The conductive undercoat layer comprising conductive agents serves as an intermediary that enhances electrical conductivity at the interface between the current collector and the positive electrode film layer. This resolves the contradiction between power and device complexity by introducing a conductive intermediate layer that improves charge transfer.
4Quantity of substance
If manganese-containing positive electrode material is used, then capacity is achieved, but interfacial reactions with electrolyte consume electrolyte and reduce safety
Solution Approach 1:
The conductive undercoat layer acts as a protective intermediary that prevents direct contact between the manganese-containing positive electrode material and the electrolyte, thereby inhibiting interfacial reactions and electrolyte consumption while maintaining battery capacity.
Solution Approach 2:
The core-shell structure with pyrophosphate and phosphate coating layers creates a protective barrier that reduces interfacial reactions between the manganese-containing core and the electrolyte, preventing electrolyte consumption and improving safety while preserving the capacity-providing manganese material.
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 effectively reduces manganese dissolution, enhances lithium ion transport, and improves cycling and high-temperature performance, safety, and kinetic performance of secondary batteries.
Implementation Method 1
promote lithium ion migration
Implementation Method 2
improve electrical conductivity
Implementation Method 3
inhibit manganese dissolution
Implementation Method 4
enhances lithium ion transport
Data Source
AI summary
The present application provides a positive electrode plate, a secondary battery and a power consuming device. The positive electrode plate may comprise a positive electrode current collector, a positive electrode film layer provided on at least one surface of the positive electrode current collector, and a conductive undercoat layer between the positive electrode current collector and the positive electrode film layer, wherein the positive electrode film layer may include a positive electrode film layer comprising a positive electrode active material with a core-shell structure, the positive electrode active material may comprise an inner core and a shell coating the inner core, and the conductive primer layer may comprise a first polymer, a first water-based binder and a first conductive agent.