High Voltage Lithium Battery Electrolyte Additives
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Solution Overview
Problem
Lithium secondary batteries face challenges in maintaining high voltage due to oxidative decomposition of the electrolyte, leading to reduced lifespan and increased thickness variations of the cathode at room and high temperatures.
Innovation Solution
A lithium battery design incorporating a cathode with a mixture density of 3.9 g/cc or greater, an anode, and an electrolyte with a non-aqueous organic solvent mixture including ethyl butyrate and methyl valerate, which provides an operating voltage of 4.4 V or greater, reducing oxidative decomposition and enhancing electrochemical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If charge potential is increased for high capacity, then energy density is improved, but electrolyte oxidative decomposition increases leading to reduced lifespan
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing specific additives (5-((2-methoxyethoxy)methyl)-1,3,2-dioxaborolane and vinylene carbonate) in controlled amounts (0.1-5 wt% and 0.01-1 wt% respectively). This parameter modification allows the electrolyte to form stable protective films on the cathode surface, preventing oxidative decomposition even at high charge potentials of 4.4V or higher, thus maintaining both high energy density and extended lifespan.
Solution Approach 2:
The patent introduces boron-containing additives and vinylene carbonate as intermediary substances that mediate between the high voltage cathode and the electrolyte. These intermediaries form stable interface layers (SEI films) on the cathode surface, acting as protective barriers that prevent direct contact and oxidative decomposition between the electrolyte and cathode, enabling high voltage operation without sacrificing lifespan.
2Quantity of substance
If high voltage operation is maintained, then discharge capacity is improved, but cathode thickness variations increase
Solution Approach 1:
The patent modifies the electrolyte composition parameters by adding specific concentrations of boron-containing compounds (0.1-5 wt%) and vinylene carbonate (0.01-1 wt%). These parameter changes enable the formation of uniform protective films on the cathode surface during high voltage charging, which stabilize the cathode structure and prevent thickness variations even when operating at 4.4V or higher, thus maintaining both high discharge capacity and cathode dimensional stability.
3Reliability
If electrolyte composition is modified to prevent decomposition, then lifespan is improved, but battery complexity increases
Solution Approach 1:
The patent employs a relatively simple parameter change strategy by adding only two types of additives (boron-containing compound and vinylene carbonate) in specific small amounts to the existing electrolyte system. This minimal composition modification approach achieves significant lifespan extension without substantially increasing electrolyte formulation complexity, making the solution practical for manufacturing and scaling.
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 exhibits improved lifespan characteristics and reduced thickness variations at both room and high temperatures, maintaining high discharge capacity and stability.
Implementation Method 1
an electrolyte disposed between the cathode and the anode and including a non-aqueous organic solvent
Data Source
AI summary
A lithium battery includes: a cathode having a mixture density of 3.9 g/cc or greater; an anode; and an electrolyte including a non-aqueous organic solvent disposed between the cathode and the anode, wherein the lithium battery has an operating voltage of 4.4 V or greater, and the non-aqueous organic solvent includes at least one first non-aqueous organic solvent selected from ethyl butyrate and methyl valerate, and the first non-aqueous organic solvent is contained in an amount of 20 to 50 volume % with based on a total volume of the non-aqueous organic solvent.