Nitrile Electrolyte and Anode Layout for High-Voltage Li-Ion Cells
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge is to improve the energy density of lithium-ion batteries while maintaining the stability of both the positive and negative electrodes, as increasing the charging cut-off voltage enhances energy density but compromises positive electrode stability.
Innovation Solution
Incorporating a nitrile compound in the electrolyte, specifically at a mass percentage of 0.1% to 10%, which improves the stability of the positive electrode but requires careful management to prevent copper dissolution from the negative electrode current collector, particularly at the welding position of the tab.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the charging cut-off voltage is increased to improve energy density, then the energy density is improved, but the positive electrode stability deteriorates
Solution Approach 1:
The patent introduces nitrile compounds as electrolyte additives that modify the electrochemical parameters of the system. These compounds change the decomposition potential and surface properties of the positive electrode, enabling stable operation at higher voltages (4.4V-4.6V) without compromising electrode stability. The nitrile compounds alter the electrolyte's interaction with the electrode surface, fundamentally changing the voltage-stability relationship.
Solution Approach 2:
The nitrile compound acts as an intermediary substance between the electrolyte and the positive electrode. It mediates the interaction by forming protective films on the electrode surface, which allow high voltage operation while preventing direct harmful interactions between the electrolyte and electrode at elevated potentials. This intermediary layer resolves the contradiction by decoupling voltage increase from stability deterioration.
2Stability of the object's composition
If nitrile additives are added to improve positive electrode stability, then the cycle performance is improved, but copper dissolution from the negative electrode current collector occurs
Solution Approach 1:
The patent applies local quality by using nitrile compounds that preferentially interact with and protect the positive electrode surface, while the concentration and distribution are controlled to minimize impact on the negative electrode. The additive creates localized protective effects where needed (at the positive electrode) without causing harmful side effects (copper dissolution at the negative electrode) when used within the specified concentration range of 0.01-5 wt%.
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 approach enables high-voltage cycle stability, reduces self-discharging, and enhances safety characteristics of lithium-ion batteries by optimizing the nitrile compound content and electrode design.
Implementation Method 1
nitrile additives may effectively improve stability of positive electrode
Implementation Method 2
electrolyte includes a nitrile compound
Data Source
AI summary
An electrochemical device, including a positive electrode, a negative electrode, a separator and an electrolyte. The electrolyte includes a nitrile compound, and the mass percentage of the nitrile compound in the electrolyte is A %; the negative electrode includes a current collector, wherein the current collector includes a first region and a second region; the first region is provided with a negative electrode active substance layer; the second region does not include a negative electrode active substance layer; the area of the second region is B % of the surface area of the current collector; and A×B<600.