Halogenated Alkane Electrolyte for Lithium Metal Battery Cycle Life
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Solution Overview
Problem
Rechargeable lithium ion batteries with a lithium metal anode face challenges such as high reactivity, unstable solid electrolyte interphase formation, dendrite growth, and volume change, leading to low coulombic efficiency, shortened life, and safety issues, which are exacerbated by the high viscosity of high salt concentration electrolytes.
Innovation Solution
Incorporating a halogenated alkane in small amounts (0.05% to 2% by weight) into a localized high concentration electrolyte comprising a lithium salt and solvating solvent to stabilize the electrolyte and improve cycle life without adversely affecting power delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high salt concentration electrolytes are used, then cycle performance is improved, but viscosity increases which adversely affects power delivery
Solution Approach 1:
The patent modifies the chemical composition parameters of the electrolyte by introducing fluorinated carbonates with specific molecular structures (FEC, DFEC, FDMC) and controlling their concentration ratios. This changes the physical properties of the electrolyte to achieve lower viscosity while maintaining high salt concentration, thus resolving the contradiction between cycle performance and power delivery
Solution Approach 2:
The patent creates a composite electrolyte system combining multiple carbonate solvents (EC, DMC, DEC) with fluorinated additives (FEC, DFEC, FDMC) and lithium salts. This composite formulation synergistically improves both cycle stability and ionic conductivity, overcoming the limitations of single-component electrolytes
2Stability of the object's composition
If high salt concentration electrolytes are used, then solid electrolyte interphase stability is improved, but dendrite formation increases
Solution Approach 1:
The fluorinated carbonate additives (FEC, DFEC, FDMC) act as intermediary substances that mediate between the lithium salt and the electrode surface. They facilitate the formation of a stable, protective SEI layer that prevents direct contact between lithium dendrites and the electrode, thus stabilizing the interface while suppressing dendrite growth
Solution Approach 2:
The patent changes the chemical composition parameters by incorporating fluorinated carbonates with specific fluorine-to-carbon ratios and molecular weights. This modifies the decomposition products of the electrolyte to form SEI layers with different physical and chemical properties that are more effective at preventing dendrite formation
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 electrolyte enhances cycle life and maintains desirable power delivery in anode-less and lithium metal batteries by forming a LiF-rich solid electrolyte interphase, reducing viscosity, and minimizing dendrite formation.
Implementation Method 1
forming a LiF-rich solid electrolyte interphase
Implementation Method 2
reducing viscosity
Implementation Method 3
minimizing dendrite formation
Data Source
AI summary
Electrolytes comprising a solvating solvent, lithium salt and a halogenated alkane in an amount of 0.05% to 5% by weight of the electrolyte improve the cycling performance of lithium ion batteries and in particular lithium ion batteries having lithium metal anodes or anode-less anodes with Li intercalating cathode (e.g., cathodes comprised of layered nickel, manganese cobalt oxides).