Electrolyte Additive for Stable CEI/SEI Films in Li-Ion Batteries
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Solution Overview
Problem
High nickel/silicon-carbon type lithium-ion batteries face structural instability issues at high temperatures, leading to deterioration of battery performance due to the instability of the CEI and SEI films, which are currently addressed by using multiple film-forming additives that introduce impurities and increase reaction complexity.
Innovation Solution
An electrolyte additive represented by a specific compound formula, which forms both a CEI and SEI film on the electrodes, utilizing a morpholinyl moiety for electron-withdrawing effects and a sulphonic acid group for electron-donating effects, thereby stabilizing the electrodes and reducing impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple film-forming additives are used to protect both positive and negative electrodes, then electrode stability is improved, but impurity formation increases and reaction process complexity increases
Solution Approach 1:
The patent combines the functions of multiple film-forming additives (phosphate for positive electrode, borate salt for negative electrode) into a single compound containing both phosphate and borate groups. This merging approach maintains the protective film-forming capability on both electrodes while eliminating the need for separate additives, thereby reducing impurity formation and simplifying the electrolyte composition.
Solution Approach 2:
The invented compound serves multiple functions simultaneously: it acts as both a positive electrode protective agent (through its phosphate group) and a negative electrode protective agent (through its borate group). This multi-functionality allows a single additive to replace multiple specialized additives, reducing overall complexity and impurity introduction while maintaining comprehensive electrode protection.
2Reliability
If multiple film-forming additives are used to protect both positive and negative electrodes, then electrode stability is improved, but device complexity increases
Solution Approach 1:
The patent merges the roles of multiple additives into a single compound molecule that contains both phosphate and borate functional groups. This structural integration simplifies the electrolyte formulation from a multi-component system to a single-component additive system, reducing the complexity of the reaction process and making the system easier to control while maintaining dual electrode protection.
Solution Approach 2:
The compound exhibits universal protective behavior toward both positive and negative electrodes through its dual functional groups. This universality eliminates the need for separate additive systems and their associated complex interactions, thereby simplifying the overall reaction process and improving controllability while achieving comprehensive electrode stability.
3Use of energy by moving object
If high nickel/silicon-carbon type lithium-ion batteries are used to achieve high energy density, then energy density is improved, but structural stability deteriorates at high temperature
Solution Approach 1:
The phosphate-borate compound performs preliminary protective action by forming stable interface films on both electrodes before high-temperature operation begins. This pre-formed protective layer prevents structural degradation and maintains electrode integrity during high-temperature charging and discharging, thereby preserving the structural stability of high energy density batteries under harsh conditions.
Solution Approach 2:
The compound provides beforehand cushioning protection by creating a stable interface layer that buffers against thermal stress and structural instability. This protective cushion prevents the electrode materials from undergoing harmful transformations at high temperatures, thereby maintaining the structural stability of high energy density batteries during operation.
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 additive improves electrode stability, reduces battery impedance, and enhances high-temperature cycle and rate performance by forming protective films on both positive and negative electrodes without the need for multiple additives, thus controlling impurity formation and maintaining battery efficiency.
Implementation Method 1
During the first charge/discharge cycle, the decomposition reaction of the film-forming additives takes place preferentially over the solvent, and the decomposition product thereof forms a stable and dense SEI film on the surface of the positive electrode
Implementation Method 2
During the first charge/discharge cycle, the decomposition reaction of the film-forming additives takes place preferentially over the solvent, and the decomposition product thereof forms a stable and dense SEI film on the surface of the negative electrode
Implementation Method 3
utilizing a morpholinyl moiety for electron-withdrawing effects and a sulphonic acid group for electron-donating effects, thereby stabilizing the electrodes
Implementation Method 4
utilizing a morpholinyl moiety for electron-withdrawing effects and a sulphonic acid group for electron-donating effects, thereby stabilizing the electrodes
Data Source
AI summary
An electrolyte additive, an electrolyte and a lithium-ion secondary battery containing same, and the use thereof are provided. The electrolyte additive includes a compound as represented by a formula (1) as follows:wherein R1 is a substituted or unsubstituted C1-6 alkyl group, and R2 is selected from the group consisting of a substituted or unsubstituted C1-6 aliphatic hydrocarbylene groups and a 6-10 membered substituted or unsubstituted carbocyclic or heterocyclic aromatic group, wherein the heterocyclic aromatic group comprises 1 to 3 heteroatoms selected from N, S, O or any combination thereof.