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Solution Overview
Problem
Lithium-ion batteries face issues with deteriorated high temperature cycling performance and low hot box pass rate due to oxidation and decomposition of the electrolyte solution at high voltage, as well as instability of the positive electrode interface.
Innovation Solution
The battery incorporates a positive electrode material with a complete crystalline structure, optimized through specific intensity ratios of XRD diffraction peaks, and an electrolyte solution containing a nitrile compound, such as adiponitrile, to enhance stability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the voltage of the positive electrode is increased to improve energy density, then energy density is improved, but high temperature cycling performance deteriorates and electrolyte solution oxidation and decomposition occur
Solution Approach 1:
A coating layer comprising at least one of a metal oxide or a metal hydroxide is formed on the surface of the positive electrode material. This coating layer acts as an intermediary between the positive electrode material and the electrolyte solution, preventing direct harmful interactions while allowing lithium ion insertion and extraction, thereby improving high temperature cycling performance and preventing electrolyte oxidation at high voltage
Solution Approach 2:
The voltage of the positive electrode is controlled to be 4.35 V or higher but not higher than 4.50 V vs. Li/Li+. By optimizing the voltage parameter within this specific range and combining it with the coating layer, the patent achieves improved energy density while maintaining reliable high temperature cycling performance and preventing electrolyte decomposition
2Quantity of substance
If the voltage of the positive electrode is increased to improve energy density, then energy density is improved, but safety performance deteriorates
Solution Approach 1:
The coating layer of metal oxide or metal hydroxide serves as a protective intermediary on the positive electrode material surface. It prevents direct contact between the high-voltage positive electrode and the electrolyte solution, eliminating the harmful oxidation and decomposition reactions that would compromise safety, while still permitting necessary lithium ion transport for high energy density operation
3Reliability
If a coating layer of metal oxide or metal hydroxide is formed on the positive electrode material, then high temperature cycling performance is improved, but manufacturing complexity increases
Solution Approach 1:
The coating layer thickness is controlled to be 1 nm to 100 nm, and the content of the coating layer is controlled to be 1 wt% to 50 wt% based on the mass of the positive electrode material. By specifying these quantitative parameters, the patent provides clear manufacturing targets that balance the need for improved high temperature cycling performance with manufacturing feasibility and 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
This configuration significantly improves normal temperature storage performance, cycling performance, and hot box pass rate by stabilizing the positive electrode interface, reducing interface impedance, and protecting against oxidative decomposition.
Implementation Method 1
the nitrile compound can be bonded to high-valence cobalt ions on a positive electrode interface, thereby reducing an oxidative catalytic effect of the high-valence cobalt ions on the electrolyte solution
Implementation Method 2
the positive electrode material has high crystallization integrity, a layered structure thereof has good stability, and a high degree of order is achieved in terms of the ion arrangement of cations
Data Source
AI summary
A battery includes a positive electrode material with a complete crystalline structure. The positive electrode material meets 1.3≤I003/I104≤3, 0.02≤I006/I003≤0.15, and 0.06≤I006/I104≤0.15. The battery further includes an electrolyte solution, the electrolyte solution includes a first additive, the first additive includes a nitrile compound, and the electrolyte solution meets the following relational expression: 3%≤B≤6%, where B is a percentage of a mass of the nitrile compound in a total mass of the electrolyte solution. The positive electrode material has high thermal stability, which is conducive to improving a hot box pass rate of the battery and improving high temperature storage performance and cycling performance of the battery.