Positive Electrode Sheet Coating for High-Voltage Overcharge Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing secondary batteries exhibit abnormally increased charging capacity under high-rate and high cut-off voltage charging conditions, leading to overcharging risks due to oxidative decomposition of the solvent in the electrolyte solution.
Innovation Solution
A positive electrode plate comprising a polymer and an organic solvent with an electrochemical oxidation window higher than 4 V is used, blocking direct contact between the positive electrode active material and the solvent to prevent oxidative decomposition and side reactions, thereby reducing the risk of overcharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-rate and high cut-off voltage charging is performed, then charging speed and energy density are improved, but oxidative decomposition of the electrolyte solvent occurs causing overcharge risk
Solution Approach 1:
A polymer layer is introduced as an intermediary substance between the positive electrode active material and the electrolyte solvent. This polymer layer contains an organic solvent with high electrochemical oxidation window (>4V) that prevents direct contact between the electrode and the electrolyte solvent, thereby blocking oxidative decomposition while allowing ion transport for high-rate charging
Solution Approach 2:
The invention changes the chemical composition parameters of the interface layer by selecting a polymer and organic solvent with specific electrochemical properties (oxidation window >4V). This parameter change enables the interface layer to remain stable at high cut-off voltages (>4V) where conventional electrolytes would decompose, thus enabling safe high-voltage fast charging
2Quantity of substance
If high cut-off voltage charging (>4V) is performed, then battery capacity is improved, but side reactions on the positive electrode side occur
Solution Approach 1:
The invention changes the electrochemical stability window parameter of the positive electrode interface by using a polymer-organic solvent composite with oxidation resistance >4V. This allows the battery to operate at high cut-off voltages (>4V) to achieve higher capacity without triggering oxidative side reactions that would occur with conventional electrolytes
Solution Approach 2:
The polymer layer acts as a mediator that enables high-voltage operation by providing a chemically stable interface. The organic solvent within the polymer matrix has higher oxidation resistance than conventional electrolyte solvents, preventing side reactions while allowing lithium ion transport necessary for high capacity
3Use of energy by moving object
If conventional electrolyte solvent is used, then ion conductivity is maintained, but oxidative decomposition occurs under high-rate charging
Solution Approach 1:
The invention uses a composite material system consisting of a polymer matrix filled with organic solvent particles. This composite structure combines the ion conductivity benefits of liquid electrolyte with the stability and protective functions of solid polymer, preventing oxidative decomposition while maintaining efficient lithium ion transport for high-rate charging
Solution Approach 2:
The invention applies local quality change by creating a polymer layer with specific local composition (polymer + organic solvent with >4V oxidation window) at the positive electrode interface. This localized modification provides oxidative protection exactly where needed (at the high-voltage positive electrode) while maintaining overall battery ion conductivity
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 polymer and organic solvent combination effectively prevents oxidative decomposition of the electrolyte solvent, reducing the risk of overcharge by blocking direct contact and preventing additional electrons from reaching the negative electrode, thus maintaining stable battery charging capacity.
Implementation Method 1
the polymer filled with the organic solvent can block the direct contact between the positive electrode active material and the solvent in the electrolyte solution of the battery, thereby avoiding the oxidative decomposition of the solvent in the electrolyte solution
Implementation Method 2
since the electrochemical oxidation window of the organic solvent is higher than 4 V, that is, the organic solvent will not undergo an oxidation reaction on the positive electrode side under the condition of charging at a high cut-off voltage (> 4 V)
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
The present application discloses a positive electrode plate and a preparation method therefor, a positive electrode plate, a battery and an electrical apparatus. The positive electrode plate comprises a positive electrode current collector, and at least one side of the positive electrode plate away from the positive electrode current collector comprises a polymer and an organic solvent, wherein the organic solvent is located in the polymer, and the electrochemical oxidation window of the organic solvent is greater than 4 V