Lithium-Ion Battery Electrolyte Additives for Nickel-Rich Cathodes
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Solution Overview
Problem
Conventional lithium-ion battery electrolyte formulations face challenges in stabilizing the cathode-electrolyte interface, particularly with nickel-rich cathode active materials, due to parasitic reactions and electrolyte decomposition, leading to impedance growth and capacity decay.
Innovation Solution
The use of functionalized electrolyte additives that create a physical barrier on the cathode surface, scavenging hydrogen fluoride and water, and oxidizing before electrolyte solvents, to inhibit decomposition and improve interface stability, with specific additives containing less than nine carbons, unsaturated bonds, and boron, phosphorus, or S—N functional groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If nickel-rich cathode active material is used to increase specific capacity, then energy density is improved, but interface stability deteriorates due to parasitic reactions and electrolyte decomposition
Solution Approach 1:
The patent introduces a fluorinated cyclic carbonate additive as an intermediary substance that mediates between the nickel-rich cathode and the electrolyte. This additive preferentially reacts with trace water to form a protective interface layer, preventing direct contact and parasitic reactions between the electrolyte and nickel cathode material, thus stabilizing the interface while maintaining high capacity
Solution Approach 2:
The patent converts the harmful effect of trace water (which causes HF formation and nickel dissolution) into a beneficial protective mechanism. The fluorinated additive deliberately reacts with trace water first, converting it into harmless byproducts and forming a stable interface film, thereby protecting the nickel-rich cathode from water-induced degradation
2Ease of manufacture
If conventional electrolyte formulation is used, then manufacturing simplicity is maintained, but capacity decay increases due to electrolyte decomposition at the cathode interface
Solution Approach 1:
The patent modifies the electrolyte formulation by incorporating fluorinated cyclic carbonate additives with specific molecular characteristics (fluorine substitution, cyclic structure). This parameter change in the additive composition enables preferential reaction with trace water and formation of stable interface films, significantly reducing electrolyte decomposition and capacity decay while maintaining formulation simplicity
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 solution enhances the stability of the cathode-electrolyte interface, preventing nickel dissolution and electrolyte oxidation, thereby improving the durability and capacity retention of lithium-ion batteries, especially with nickel-based cathode active materials.
Implementation Method 1
the additive... scavenges hydrogen fluoride and/or water
Implementation Method 2
oxidizes before the electrolyte solvents
Implementation Method 3
organically create a physical barrier on the cathode surface. The physical barrier is a protective, uniform film
Implementation Method 4
scavenges hydrogen fluoride and/or water, with hydrogen fluoride quenching preferred
Data Source
AI summary
A lithium-ion battery has anode active material, nickel-based cathode active material, and an electrolyte. The electrolyte has the following formulation: a carbonate-based solvent; LiPF6; vinylene carbonate; and an additive that satisfies the following: less than or equal to nine carbons; at least one unsaturated bond; a predicted oxidation potential Vox of 2.0<Vox<4.5; and a boron atom, a phosphorus atom or an S—N functional.