Li-Ion Cathode Lithium Supplement and Electrolyte for High-Temperature Safety
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Solution Overview
Problem
Lithium-ion secondary batteries face challenges in achieving high energy density and improved safety performance, particularly at high temperatures, due to irreversible lithium loss and metal ion dissolution, which leads to reduced cycling and storage performance and increased safety risks.
Innovation Solution
Incorporating a lithium-rich metal oxide as a positive electrode supplementing material and controlling the fluorine content in the electrolyte lithium salt within a specific range to reduce metal ion dissolution and enhance lithium intercalation capacity, thereby improving high-temperature safety and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-nickel lithium-rich materials are used as positive electrode active materials to increase energy density, then the energy density is improved, but metal ion dissolution increases leading to reduced safety performance and cycling life
Solution Approach 1:
The patent uses a composite material system consisting of high-nickel lithium-rich positive electrode active material (LiNi0.8Co0.1Mn0.1O2) combined with a specifically formulated electrolyte containing fluorinated lithium salts (LiPF6, LiBF4) and cyclic carbonate solvents. This composite approach allows the battery to achieve high energy density while the electrolyte composition suppresses metal ion dissolution and improves safety performance at high temperatures
Solution Approach 2:
The patent optimizes the chemical composition parameters of the electrolyte by controlling the ratio of lithium salts (LiPF6 and LiBF4) and cyclic carbonate content (15-30% by weight). This parameter optimization reduces metal ion dissolution from the high-nickel positive electrode, thereby improving safety performance and cycling stability while maintaining high energy density
2Quantity of substance
If high-nickel lithium-rich materials are used to increase capacity, then the discharge capacity is improved, but irreversible lithium loss increases leading to reduced cycling performance
Solution Approach 1:
The patent optimizes electrolyte composition parameters including cyclic carbonate content (15-30% by weight) and lithium salt ratios to minimize irreversible lithium loss during initial charging and subsequent cycling. This parameter optimization preserves more lithium in the system, improving cycling performance while maintaining high discharge capacity
Solution Approach 2:
The electrolyte acts as an intermediary medium that facilitates lithium ion transport between electrodes while protecting the high-nickel positive electrode material. The specific electrolyte composition (containing fluorinated lithium salts and optimized cyclic carbonate content) reduces parasitic reactions and lithium consumption, thereby improving cycling performance
3Ease of manufacture
If conventional electrolytes are used to simplify the electrolyte formulation, then the ease of manufacture is improved, but metal ion dissolution increases at high temperatures leading to reduced safety
Solution Approach 1:
The patent modifies the electrolyte composition by incorporating fluorinated lithium salts (LiPF6, LiBF4) and optimizing cyclic carbonate content (15-30% by weight). These compositional changes enhance the electrolyte's ability to suppress metal ion dissolution at high temperatures while maintaining ease of manufacture through standard electrolyte preparation processes
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 solution enhances the battery's high-temperature cycling and storage performance by reducing metal ion dissolution, improving discharge capacity, and minimizing safety risks through controlled lithium release and electrolyte stability.
Implementation Method 1
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
Implementation Method 3
achieves charging and discharging by repeated deintercalation and intercalation of lithium ions between the positive electrode and negative electrode
Data Source
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AI summary
Disclosed are a lithium-ion secondary battery and a preparation method therefor, a battery module, a battery pack, and a device. The lithium-ion secondary battery comprises a positive electrode pole piece, a negative electrode pole piece and an electrolyte solution. The positive electrode pole piece comprises a positive electrode active material and a positive electrode lithium supplementing material. The positive electrode lithium supplementing material comprises a lithium-rich metal oxide, and the lithium-rich metal oxide contains one or more elements among Ni, Co, Fe, Mn, and Cu. The electrolyte solution comprises an electrolyte lithium salt and a solvent, and the ratio ε of the total mass of fluorine in the anion of the electrolyte lithium salt relative to the total mass of the electrolyte solution is less than 14%.