Nitrogen Electrolyte Additive for Active Lithium Retention
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Solution Overview
Problem
Current lithium-ion batteries face challenges in achieving higher energy density due to the consumption of lithium sources during the formation of the solid electrolyte interphase (SEI) film, leading to reduced first-cycle coulombic efficiency and cycle performance, exacerbated by irreversible phase transitions and oxidative degradation of the electrolyte.
Innovation Solution
Incorporation of an electrolyte solution additive with nitrogen atoms having lone pair electrons that react with electron-deficient species (R+) to form -N+−R, reducing the reduction of R+ at the negative electrode and minimizing damage to the SEI film, thereby conserving active lithium and enhancing battery efficiency and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If pre-lithiation is performed using a lithium supplement additive, then energy density and first-cycle coulombic efficiency are improved, but oxygen radicals are generated causing electrolyte oxidation and SEI damage
Solution Approach 1:
The nitrogen-containing compound acts as an intermediary substance that intercepts oxygen radicals before they can oxidize the electrolyte or damage the SEI film. The lone pair electrons on nitrogen atoms provide a safe pathway for radical termination, converting harmful oxygen radicals into harmless nitrogen oxides while protecting the battery system components
Solution Approach 2:
The invention converts the harmful oxygen radicals generated during pre-lithiation into beneficial protective effects. By introducing nitrogen-containing compounds that preferentially react with oxygen radicals, the harmful oxidation process is redirected to form stable nitrogen-oxygen bonds, thereby protecting the electrolyte and SEI film while maintaining the energy density benefits of pre-lithiation
2Quantity of substance
If R+ is reduced at the negative electrode, then lithium supplement function is achieved, but active lithium is consumed and SEI is damaged
Solution Approach 1:
The nitrogen-containing compound serves as an intermediary that captures R+ species through coordination bonding via lone pair electrons, preventing R+ from reaching the negative electrode. This intermediary mechanism allows the lithium supplement to function without causing harmful reduction reactions at the electrode surface
Solution Approach 2:
The invention introduces a feedback mechanism where nitrogen-containing compounds monitor and control R+ species concentration in the electrolyte. By providing a continuous scavenging action that responds to R+ generation, the system maintains balance between lithium supplement benefits and prevention of active lithium consumption
3Reliability
If SEI film is formed during first charge, then electrode protection is achieved, but lithium sources are consumed reducing coulombic efficiency
Solution Approach 1:
The nitrogen-containing compounds are introduced into the electrolyte before battery operation to perform preliminary protection of the SEI film. By pre-establishing a protective chemical environment that scavenges harmful species, the SEI film formation process is optimized to consume less lithium while achieving adequate electrode protection
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 electrolyte solution additive effectively improves initial efficiency and cycle performance by minimizing lithium consumption and SEI film damage, while simplifying the battery preparation process without the need for additional modifications to the positive electrode.
Implementation Method 1
The lone pair electrons on the nitrogen atom make the nitrogen atom electron-rich and easily react with electron-deficient R+ to form −N+−R
Implementation Method 2
reduces consumption of active lithium at the negative electrode, and reduces damage to an SEI film
Data Source
AI summary
An electrolyte solution additive, an electrolyte solution, a secondary battery, and an electrical device are disclosed. In a structural formula of the electrolyte solution additive, at least one nitrogen atom having lone pair electrons is included. The lone pair electrons on the nitrogen atom have a strong electron-donating ability, and easily react with electron-deficient R+ to form −N+−R. This reduces a possibility of reduction of R+ at a negative electrode, reduces damage to an SEI film, and reduces consumption of active lithium at the negative electrode, to improve initial efficiency and cycle performance of a battery.