Lithium-Ion Cathode Composition for High-Temperature Cycling Stability
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Solution Overview
Problem
Lithium-ion secondary batteries face challenges in achieving high energy density and high-temperature safety performance due to irreversible lithium loss and metal ion dissolution, which affects their cycling and storage performance.
Innovation Solution
Incorporating a lithium-rich metal oxide with elements like Ni, Co, Fe, Mn, and Cu as a positive electrode supplementing material, and optimizing the electrolyte's fluorine content within a specific range to reduce metal ion dissolution and enhance ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium-rich metal oxide is added to the positive electrode to compensate for irreversible lithium loss and improve high-temperature cycling life, then the battery's high-temperature cycling and storage performance is improved, but metal ion dissolution increases leading to higher self-discharge rate and reduced energy density
Solution Approach 1:
The patent applies parameter changes by precisely controlling the fluorine content percentage in the electrolyte lithium salt anions within a specific range (5%≤ε≤14%). This parameter optimization reduces metal ion dissolution while maintaining the benefits of lithium-rich metal oxide for high-temperature cycling performance. The fluorine content parameter is adjusted to achieve the optimal balance between stability and performance.
Solution Approach 2:
The patent uses composite materials by combining lithium-rich metal oxide (containing Ni, Co, Fe, Mn, and/or Cu) with a fluorine-containing electrolyte lithium salt. This composite approach creates a synergistic effect where the lithium-rich metal oxide provides lithium supplementation and high-temperature stability, while the fluorine-containing electrolyte suppresses metal ion dissolution, achieving both improved cycling life and reduced self-discharge.
2Reliability
If fluorine content in electrolyte lithium salt is increased to reduce metal ion dissolution and improve safety, then high-temperature safety performance is improved, but ionic conductivity may be reduced
Solution Approach 1:
The patent applies parameter changes by optimizing the fluorine content percentage (ε) in the electrolyte lithium salt anions within a specific range (5%≤ε≤14%). This controlled parameter adjustment ensures sufficient fluorine content to reduce metal ion dissolution and improve safety, while preventing excessive fluorine that would harm ionic conductivity. The parameter is tuned to achieve the optimal balance between safety and energy efficiency.
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 approach improves the battery's high-temperature cycling and storage performance, reduces self-discharge, and enhances safety by minimizing metal deposition and gas production, leading to increased energy density and extended lifespan.
Implementation Method 1
the lithium ion secondary battery achieves charging and discharging by repeated deintercalation and intercalation of lithium ions between the positive electrode and negative electrode
Implementation Method 2
the electrolyte comprises an electrolyte lithium salt and a solvent, and has a percentage ε of the total mass of a fluorine element in the anions of the electrolyte lithium salt relative to the total mass of the electrolyte
Implementation Method 3
the lithium ion secondary battery achieves charging and discharging by repeated deintercalation and intercalation of lithium ions between the positive electrode and negative electrode
Data Source
AI summary
A lithium ion secondary battery and a preparation method therefor, a battery module, a battery pack, and a device are provided. In some embodiments, the lithium ion secondary battery comprises a positive electrode plate, a negative electrode plate and an electrolyte, wherein the positive electrode plate comprises a positive electrode active material and a positive electrode lithium-supplementing material comprising a lithium-rich metal oxide, and the lithium-rich metal oxide comprises one or more elements of Ni, Co, Fe, Mn, and Cu; the electrolyte comprises an electrolyte lithium salt and a solvent, and has a percentage ε of the total mass of a fluorine element in the anions of the electrolyte lithium salt relative to the total mass of the electrolyte of <14%.