Lithium Battery Electrolyte Additives for High-Density Anodes
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Solution Overview
Problem
Increasing the density of the negative electrode in rechargeable lithium batteries leads to a decrease in cycle-life and an increase in battery thickness, which are undesirable outcomes.
Innovation Solution
A rechargeable lithium battery design that incorporates a negative electrode with an active mass density of 1.7 g/cc or higher, utilizing an electrolyte comprising a lithium salt, a non-aqueous organic solvent, a first additive with both hydrophilic and hydrophobic groups, and a second additive such as lithium difluoro(oxalato)borate, which helps stabilize the lithium salt and prevent the formation of harmful species like HF.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the density of the negative electrode is increased, then the energy density of the battery is improved, but the battery thickness increases and cycle-life decreases
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing specific additives (lithium difluoro(oxalato)borate and fluoroalkyl group-containing compounds) to modify the electrolyte's interaction with the high-density negative electrode, enabling the system to achieve high energy density while maintaining acceptable cycle-life through controlled side reactions and improved interface stability
Solution Approach 2:
The patent uses electrolyte additives as intermediary substances that mediate between the high-density negative electrode and the bulk electrolyte. These additives form protective interface layers that prevent harmful direct interactions, allowing the high-density electrode to function without causing excessive thickness increase or cycle-life degradation
2Quantity of substance
If the density of the negative electrode is increased, then the energy density of the battery is improved, but the battery thickness increases
Solution Approach 1:
The patent modifies the electrolyte composition parameters by adding specific chemical compounds that change the electrolyte's physical and chemical properties, enabling better wetting and distribution characteristics that allow high-density electrode packing without proportionally increasing battery thickness
3Power
If lithium ions are intercalated/deintercalated from the positive electrode and negative electrode, then electrical energy is produced, but harmful species like HF are formed and lithium salt is consumed
Solution Approach 1:
The patent converts the potentially harmful reaction between lithium salt and electrolyte into a beneficial process by using additives that preferentially react to form protective layers. The lithium difluoro(oxalato)borate and fluoroalkyl additives sacrifice themselves to form stable interface films, preventing the formation of harmful HF species while enabling continuous electrical energy production
Solution Approach 2:
The electrolyte additives act as intermediary substances that intervene in the reaction between lithium salt and water/moisture. These additives form protective barrier layers at the electrode-electrolyte interface, preventing direct contact between harmful species and active materials, thus enabling sustained electrical energy production without degradation
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 design effectively increases the negative electrode density while minimizing the adverse effects on battery thickness and cycle-life, even at high voltage and temperature conditions.
Implementation Method 1
an electrolyte, and electrical energy is produced through oxidation and reduction reactions if lithium ions are intercalated/deintercalated from the positive electrode and negative electrode
Implementation Method 2
electrical energy is produced through oxidation and reduction reactions if lithium ions are intercalated/deintercalated from the positive electrode and negative electrode
Implementation Method 3
a negative electrode including a negative electrode active material; and an electrolyte, wherein an active mass density of the negative electrode is greater than or equal to about 1.7 g/cc
Data Source
AI summary
Disclosed is a rechargeable lithium battery, the rechargeable lithium battery including a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and an electrolyte, wherein an active mass density of the negative electrode is greater than or equal to about 1.7 g/cc, and the electrolyte includes a lithium salt; a non-aqueous organic solvent; a first additive represented by Chemical Formula 1; and a second additive represented by Chemical Formula 2: