High-Nickel NCA Battery Electrolyte for Thermal Stability
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Solution Overview
Problem
Lithium nickel cobalt aluminum oxide (NCA) batteries with high nickel ratios face challenges in thermal stability and safety due to exothermic reactions, which affect their efficiency and reliability, especially in high-capacity applications like electric vehicles.
Innovation Solution
A lithium-ion battery design incorporating a cathode with a lithium nickel cobalt aluminum oxide compound (Li(NiaCobAlc)O2) and an electrolyte containing fluoroethylene carbonate, optimized through specific preparation methods and ratios, enhances charge-discharge efficiency and safety by stabilizing the electrochemical reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the nickel ratio in NCA cathode material is increased to achieve higher capacity, then the battery capacity is improved, but the thermal stability deteriorates leading to higher exothermic reaction risk
Solution Approach 1:
The patent introduces fluoroethylene carbonate (FEC) as an intermediary additive in the electrolyte. This mediator forms a protective interface layer between the high-nickel NCA cathode and the electrolyte, suppressing direct harmful interactions while allowing beneficial electrochemical reactions. The FEC additive concentration is optimized at 5-15% by volume to achieve the best balance between capacity and safety.
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by adding fluoroethylene carbonate in specific concentrations (5-15% by volume). This parameter change transforms the electrolyte's properties to provide better thermal stability and interface protection, enabling the battery to safely operate with high-nickel (a≥0.85) NCA cathode material that would otherwise be too unstable.
2Use of energy by moving object
If the nickel ratio in NCA cathode material is increased to achieve higher capacity, then the energy density is improved, but the safety deteriorates due to increased exothermic reaction
Solution Approach 1:
Fluoroethylene carbonate acts as a protective intermediary that forms a stable interface film on the cathode surface. This film serves as a barrier that prevents direct contact between the high-nickel NCA material and the electrolyte, thereby suppressing exothermic reactions while still permitting efficient lithium ion transport for high energy density operation.
Solution Approach 2:
The patent converts the potentially harmful exothermic reaction tendency of high-nickel NCA material into a beneficial outcome by using FEC additive. The additive preferentially reacts to form a stable protective layer, transforming what would be a safety hazard into a protective mechanism that enables safe high-energy-density operation.
3Productivity
If the nickel ratio in NCA cathode material is increased to achieve higher capacity, then the charge-discharge efficiency is improved, but the stability of electrochemical reaction deteriorates
Solution Approach 1:
The FEC additive serves as a stabilizing intermediary that creates a more stable electrochemical interface. This interface layer ensures consistent and stable electrochemical reactions during charge-discharge cycles, preventing the instability that would normally occur with high-nickel NCA material, thereby maintaining high charge-discharge efficiency over extended cycling.
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 battery achieves improved charge-discharge efficiency and safety with increased capacity retention and thermal stability, reducing the risk of explosions and maintaining performance over multiple cycles, even at high nickel ratios.
Implementation Method 1
the anode is usually a graphite material having a theoretical capacity of approximately 372 mAh/g and a high stability due to only 10% volume expansion upon an electrochemical reaction
Implementation Method 2
the higher amount of nickel in a crystal structure results in a lower thermal stability of this material which could lead to a higher exothermic reaction in application and an explosion
Implementation Method 3
an electrolyte comprising lithium salt, carbonate solvent, and an additive
Data Source
AI summary
The present invention relates to a lithium-ion battery comprising a cathode comprising an active material comprising lithium nickel cobalt aluminum oxide compound, an anode comprising active material comprising graphite, and an electrolyte comprising lithium salt, carbonate solvent, and an additive, wherein lithium nickel cobalt aluminum oxide compound has a formula Li(NiaCobAlc)O2, whereby a≥0.85, 0<b<1, 0<c<1 and the sum of a, b, and c is 1, and the additive is fluoroethylene carbonate in an amount ranging from 0.2-4 vol %, based on the total amount of electrolyte. Furthermore, the invention also discloses a method for preparing the lithium-ion battery according to the present invention.