Secondary Battery Electrolyte Additives for Lithium Supplement Side Reactions
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Solution Overview
Problem
Existing secondary batteries face inefficiencies in lithium utilization due to the formation of a solid electrolyte film layer during charging, leading to lithium source consumption and reduced recyclable lithium utilization, which affects charge/discharge capacity and service life.
Innovation Solution
Incorporating a specific lithium supplement, such as Li2O, Li2O2, or Li5FeO4, with nitrone derivatives like N-tert-butyl-α-phenylnitrone in the positive electrode film or electrolyte solution, which improves lithium supplement utilization efficiency by neutralizing free electrons and reducing harmful side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium supplement is added to compensate for lithium source consumption during SEI formation, then charge/discharge capacity is improved, but utilization efficiency of lithium supplement decreases due to side reactions
Solution Approach 1:
The patent introduces a mediator substance (lithium supplement such as Li2O, Li2O2, or Li5FeO4) that acts as an intermediate carrier to transfer lithium ions from the positive electrode to the negative electrode. This mediator enables indirect lithium transport, compensating for lithium consumption during SEI formation while reducing direct side reactions between the electrolyte and electrode materials, thereby improving both charge/discharge capacity and utilization efficiency
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by adding specific additives (such as fluoroethylene carbonate (FEC) at 5-20 mass%, or a combination of dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) in specific ratios). These parameter changes modify the electrochemical properties of the electrolyte, reducing its reactivity with lithium supplements and improving the utilization efficiency while maintaining adequate ionic conductivity for charge/discharge operations
2Quantity of substance
If lithium supplement is added to make up for lithium source loss, then charge/discharge capacity is improved, but service life decreases due to harmful side reactions
Solution Approach 1:
The lithium supplement serves as a stable intermediary that provides lithium ions without directly participating in harmful side reactions. By using chemically stable compounds like Li2O, Li2O2, or Li5FeO4 as intermediaries, the system can replenish lithium ions needed for capacity while avoiding the degradation reactions that would otherwise occur between the electrolyte and electrode materials, thus extending service life
Solution Approach 2:
The patent modifies the electrolyte composition parameters by introducing specific additives that change the electrochemical stability window and reduce reactivity. For example, adding FEC (5-20 mass%) or optimizing the DMC/EMC ratio creates a more stable electrolyte environment that prevents harmful side reactions during long-term cycling, thereby improving service life while maintaining the enhanced capacity provided by the lithium supplement
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
Enhances the charge/discharge capacity and service life of secondary batteries by optimizing lithium supplement utilization and reducing side reactions, while maintaining safety and stability.
Implementation Method 1
the additive (A) can improve the utilization efficiency of the lithium supplement, so as to further improve the charge/discharge capacity and service life of the secondary battery... the harmful side reaction caused by the migration of lithium ions of the lithium supplement can be effectively reduced
Data Source
AI summary
A secondary battery includes a positive electrode plate and an electrolyte solution. The positive electrode plate includes a positive current collector and a positive electrode film provided on at least one surface of the positive current collector. The positive electrode film includes a positive electrode active material and a lithium supplement. The lithium supplement includes at least one of substances represented by formula (I) below, and the positive electrode film and/or electrolyte solution comprises one or more nitrone derivatives, a molecule of each of which includes a structure represented by formula (II) below: