Electrolyte Additives and Grain-Boundary Protection for Nickel-Rich Cathodes
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Solution Overview
Problem
Lithium-ion batteries with nickel-rich ternary materials face issues such as particle breakage during high-voltage charging, leading to increased internal stress, rapid capacity decay, and safety concerns due to electrolyte penetration and side reactions, especially during high-temperature cycling.
Innovation Solution
Incorporating a compound of Formula I and additives like LiPO2F2 in the electrolyte, along with modifying the grain boundary of the positive electrode and using a mixture of primary and secondary particles, to form a protective film and reduce gas generation and impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel-rich ternary materials are used to achieve high energy density, then the battery capacity and energy density are improved, but particle breakage occurs during high-voltage charging leading to rapid capacity decay and safety issues
Solution Approach 1:
The patent applies preliminary action by pre-modifying the grain boundaries of positive electrode particles with specific compounds (Li3PO4, Li2SiO3, or Li4Ti5O12) before battery operation. This preliminary modification creates a stable interface that prevents particle breakage during subsequent high-voltage charging cycles, thereby maintaining both high capacity and cycle stability without requiring changes to the nickel-rich cathode material composition
Solution Approach 2:
The patent uses grain boundary modification compounds as intermediary layers between the nickel-rich ternary cathode material and the electrolyte. These intermediaries (Li3PO4, Li2SiO3, Li4Ti5O12) act as protective barriers that mediate the interaction at the particle surface, preventing direct contact between the electrolyte and particle defects, thus eliminating the need to change the high-capacity cathode composition while improving cycle stability
2Power
If high-voltage charging is applied to achieve high power output, then the battery power and charging rate are improved, but internal stress increases causing particle breakage and capacity decay
Solution Approach 1:
The patent applies beforehand cushioning by depositing protective grain boundary layers (Li3PO4, Li2SiO3, or Li4Ti5O12) on particle surfaces before high-voltage charging occurs. These layers act as cushioning barriers that absorb and distribute mechanical stress during charging, preventing stress concentration at particle defects and avoiding breakage, thus enabling high power output while maintaining particle integrity
3Device complexity
If conventional electrolytes are used to maintain simplicity, then the device complexity is reduced, but high-temperature storage performance and safety are insufficient
Solution Approach 1:
The patent applies parameter changes by modifying the electrolyte composition with specific additives (1,3-propanesultone at 0.001-0.064 g per 1 g cathode material, combined with LiPO2F2 at 0.000026-0.019 g per 1 g cathode material) to change the chemical properties of the electrolyte system. This enables the formation of stable protective films at high temperatures, improving storage performance and safety without fundamentally changing the electrolyte structure or requiring complex multi-component systems
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 significantly improves the high-temperature cycle performance and storage performance of lithium-ion batteries by inhibiting particle breakage and reducing side reactions, thereby enhancing the battery's stability and capacity retention.
Implementation Method 1
Incorporating a compound of Formula I and additives like LiPO2F2 in the electrolyte, along with modifying the grain boundary of the positive electrode and using a mixture of primary and secondary particles, to form a protective film
Implementation Method 2
Incorporating a compound of Formula I and additives like LiPO2F2 in the electrolyte, along with modifying the grain boundary of the positive electrode and using a mixture of primary and secondary particles, to form a protective film and reduce gas generation and impedance
Data Source
AI summary
An electrochemical apparatus, including a positive electrode, a negative electrode, an separator, and an electrolyte, wherein the positive electrode comprises a current collector and a positive active material layer, and the positive active material layer comprises a positive active material; and the electrolyte comprises a compound of Formula I:wherein R11, R12, R13, R14, R15 and R16 are each independently selected from: H, halogen, and the following substituted or unsubstituted groups: a C1-8 alkyl group, a C2-8 alkenyl group, a C2-8 alkynyl group, or a C6-12 aryl group; and an amount of the compound of Formula I required per 1 g of the positive active material is about 0.001 g to about 0.064 g. The present application can effectively improve high-temperature storage and high-temperature cycle performance of an electrochemical apparatus.