Electrochemical device and electronic device including same
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Solution Overview
Problem
The increase in voltage of lithium-ion batteries leads to damage to the positive electrode active material and deteriorates the chemical stability of the electrolyte, affecting the floating charge performance.
Innovation Solution
An electrochemical device with a positive electrode plate, a separator, and a negative electrode plate, where the negative electrode active material layer has protruding regions on both sides, and the electrolyte includes a polynitrile compound represented by formula I-A, with specific mass percentages and dimensions to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the voltage of lithium-ion batteries is increased to improve energy density, then the energy density is improved, but the damage to the positive electrode active material and deterioration of electrolyte chemical stability worsen
Solution Approach 1:
The patent introduces a polynitrile compound as an intermediary substance added to the electrolyte at a mass percentage of 0.01% to 8%. This compound acts as a mediator that stabilizes the positive electrode plate in a charged state and reduces dissolution of transition metal ions in high potential environments, thereby protecting the electrolyte from deterioration while maintaining high voltage operation
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by incorporating specific polynitrile compounds (formulas I-A, I-B, or I-C) with controlled concentrations. This parameter change transforms the electrolyte's chemical stability properties, enabling it to withstand higher voltages without deteriorating, thus resolving the contradiction between energy density and chemical stability
2Reliability
If the mass percentage of polynitrile compound is increased to stabilize the positive electrode, then the positive electrode stability is improved, but the cost of electrolyte increases
Solution Approach 1:
The patent applies partial action by using a small but sufficient amount of polynitrile compound (0.01% to 8% mass percentage). This concentration range is carefully determined to be just enough to stabilize the positive electrode and reduce transition metal ion dissolution without excessive addition that would increase cost unnecessarily. The protruding regions (0.5 mm to 2 mm width) also represent partial action, providing localized stabilization where needed
3Reliability
If the width of protruding region is increased to prevent lithium precipitation, then lithium precipitation is suppressed, but the accumulation of polynitrile compound increases which causes abnormal lithium precipitation
Solution Approach 1:
The patent optimizes the geometric parameter of the protruding region width to a specific range (0.5 mm to 2 mm). This parameter change balances two opposing effects: sufficient width to prevent lithium precipitation while limiting the volume to avoid excessive accumulation of polynitrile compound. The optimal width ensures that the polynitrile compound can exert its stabilizing effect without causing abnormal lithium precipitation at the boundaries
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 described configuration improves the floating charge performance of the electrochemical device by stabilizing the positive electrode, reducing transition metal ion dissolution, and suppressing negative electrode impedance increase.
Implementation Method 1
an appropriate amount of the polynitrile compound can efficiently exert effect on a positive electrode, stabilize the positive electrode plate in a charged state, and reduce dissolution of transition metal ions in a high potential environment
Implementation Method 2
Lithium-ion batteries, due to their advantages such as high energy density, long cycle life, and no memory effect, are widely used in fields such as smart phones, wearable devices, consumer-grade drones, and electric vehicles
Data Source
AI summary
An electrochemical device includes a positive electrode plate, a negative electrode plate and an electrolyte, where the positive electrode plate includes a positive electrode active material layer, and the negative electrode plate includes a negative electrode active material layer. Observed along a thickness direction of the electrochemical device, in a width direction of the negative electrode plate, the negative electrode active material layer includes two protruding regions not overlapping with the positive electrode active material layer on two sides, and a width M mm of the protruding region is 0.5 mm to 2 mm. The electrolyte includes a polynitrile compound, and the polynitrile compound includes a compound represented by formula I-A. Based on a mass of the electrolyte, a mass percentage N % of the polynitrile compound is 0.01% to 8%. 0.01≤M×N<10.