Battery Separator Additives for Low-Shrinkage Lithium Supplement Cells
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Solution Overview
Problem
Existing secondary batteries face challenges in improving energy density, cycle performance, and safety performance, particularly due to thermal shrinkage of the separator and inefficiencies in lithium supplement utilization, which affect discharge capacity and service life.
Innovation Solution
Incorporating specific nitrone derivatives or piperidine derivatives as additives in the separator, combined with lithium supplements like Li2O, Li2O2, or Li5FeO4, to reduce thermal shrinkage and enhance lithium supplement utilization efficiency, thereby improving charge/discharge capacity and safety performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator is used in a secondary battery, then it prevents short-circuiting between electrodes and enables ion transfer, but it undergoes thermal shrinkage at high temperatures which compromises safety performance
Solution Approach 1:
The patent applies composite materials by coating the separator with a dual-layer structure consisting of a first coating layer (e.g., alumina, silica, or boehmite) and a second coating layer (e.g., polyacrylic acid or carboxymethyl cellulose). This composite structure combines the heat resistance of inorganic materials with the binding and dimensional stability of organic polymers, preventing thermal shrinkage while maintaining ion permeability and short-circuit prevention functions.
2Quantity of substance
If lithium supplement is added to the secondary battery, then it compensates for lithium source consumption during formation, but it undergoes side reactions with electrolyte solution reducing utilization efficiency
Solution Approach 1:
The patent uses the separator coating layers as intermediaries to control lithium supplement release. The first coating layer (inorganic) and second coating layer (organic with carboxyl or hydroxyl groups) create a controlled interface that prevents direct contact between lithium supplement and electrolyte solution, thereby reducing side reactions while still allowing lithium ions to be released and utilized in the battery.
3Quantity of substance
If lithium supplement is used in the secondary battery, then it makes up for lithium source consumption, but it reduces discharge capacity due to low utilization efficiency
Solution Approach 1:
The separator coating layers serve as intermediaries that control the interaction between lithium supplement and electrolyte. The first coating layer (alumina, silica, or boehmite) provides a physical barrier, while the second coating layer (polyacrylic acid or carboxymethyl cellulose) with functional groups creates a controlled release mechanism, maximizing lithium ion availability for discharge capacity while minimizing wasteful side reactions.
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 effectively reduces thermal shrinkage, improves overcharge prevention, and enhances the utilization efficiency of lithium supplements, leading to increased charge/discharge capacity, extended service life, and improved safety performance of secondary batteries.
Implementation Method 1
the additive (A) is selected from any one or two or more of nitrone derivatives having a structure represented by the formula (II) below in the molecule, or piperidine derivatives having a structure represented by the formula (III) below in the molecule... the additive not only reduces the thermal shrinkage of the separator
Data Source
AI summary
A secondary battery is provided, which can improve the utilization efficiency of a lithium supplement and thus the discharge capacity when a specific lithium supplement is used, and further reduce the thermal shrinkage of the separator to improve its working stability, thereby improving the safety performance and service life. The secondary battery includes a positive electrode plate, a negative electrode plate, a separator and an electrolyte solution, as well as at least one selected from the substances represented by the general formula (I) below as a lithium supplement, wherein the separator comprises a separator substrate and an additive (A), which is selected from any one or two or more of nitrone derivatives having a structure represented by the formula (II) below in the molecule, or piperidine derivatives having a structure represented by the formula (III) below in the molecule.