Secondary Battery Cathode Additives for Higher Lithium Utilization
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Solution Overview
Problem
Existing secondary batteries face inefficiencies in lithium utilization due to the consumption of lithium during the formation of a solid electrolyte interface (SEI) layer, leading to reduced charge/discharge capacity and service life, despite the use of lithium supplements which undergo metal valence changes and side reactions.
Innovation Solution
Incorporating a specific lithium supplement represented by mLi x1 O·n(Ni y1 Mn y2 Co y3 Cu y4 Fe y5 )O and nitrone derivatives as additives in the positive electrode film and/or electrolyte solution, with controlled molar ratios and particle sizes, to enhance lithium utilization efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium supplement is added to make up for lithium source consumption, then charge capacity is improved, but utilization efficiency of lithium supplement deteriorates due to side reactions
Solution Approach 1:
The patent introduces a protective coating layer comprising silicon oxide and/or silicon nitride as an intermediary substance between the lithium supplement and the electrolyte solution. This coating layer acts as a mediator that prevents direct contact and harmful side reactions between the lithium supplement and electrolyte, while still allowing lithium ion transfer. The coating layer thus enables the lithium supplement to maintain its function of replenishing lithium source without suffering from degradation through side reactions, improving utilization efficiency.
Solution Approach 2:
The patent applies surface treatment to the lithium supplement particles to form a protective coating layer with specific compositional parameters (silicon oxide and/or silicon nitride). This parameter change in the surface structure of the lithium supplement prevents direct reaction with the electrolyte solution while maintaining lithium ion conductivity. The controlled composition and thickness of the coating layer optimize both protection against side reactions and efficiency of lithium ion transfer.
2Loss of substance
If lithium supplement undergoes metal valence changes to supplement lithium source, then recyclable lithium is restored, but harmful side reactions with electrolyte solution occur
Solution Approach 1:
The protective coating layer of silicon oxide and/or silicon nitride serves as an intermediary barrier that physically separates the lithium supplement from the electrolyte solution. This intermediary layer prevents harmful chemical interactions and side reactions between the lithium supplement and electrolyte, while maintaining the necessary ionic conductivity for lithium ion transfer. The coating thus enables the lithium supplement to perform its function without generating harmful side reactions.
Solution Approach 2:
The patent employs a thin film coating layer comprising silicon oxide and/or silicon nitride that conformally covers the lithium supplement particles. This flexible thin film structure provides effective protection against side reactions while allowing lithium ion diffusion. The thin film structure maintains close contact with the lithium supplement surface, ensuring efficient ion transfer while preventing harmful chemical interactions with the electrolyte solution.
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 charge/discharge capacity and service life of secondary batteries by reducing harmful side reactions and stabilizing the lithium supplement, thereby enhancing the battery's performance and safety.
Implementation Method 1
by including a specific additive in an electrolyte solution or a positive electrode plate, the present invention can improve the utilization efficiency of the specific lithium supplement
Implementation Method 2
during the charging/discharging process, different lithium supplements will undergo various metal valence changes or side reactions with electrolyte solutions etc.
Implementation Method 3
during the first charging process, a solid electrolyte film layer (SEI) will be formed on the surface of the negative electrode, which consumes a large amount of positive electrode lithium source
Data Source
Figure 1~3
Figure 4~6
AI summary
The present application provides a secondary battery, in which the utilization efficiency of a lithium supplement can be improved when a specific lithium supplement is used, thereby improving the discharge capacity, safety performance and service life of the secondary battery. The secondary battery includes a positive electrode plate, a negative electrode plate and an electrolyte solution. The positive electrode plate comprises a positive current collector and a positive electrode film provided on at least one surface of the positive current collector, wherein the positive electrode film comprises a positive electrode active material and at least one selected from the lithium supplement represented by general formula (I) below, and the above-mentioned positive electrode film and/or electrolyte solution comprises any one or two or more selected from nitrone derivatives having a structure represented by the formula (II) below in the molecule as an additive (A). mLix1O·n(Niy1Mny2Coy3Cuy4Fey5)O (I)