High-Concentration LiDFOB Electrolyte for Stable Lithium Plating
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Solution Overview
Problem
Lithium metal batteries face limitations due to poor mechanical properties and reactivity, leading to rapid capacity decay and limited cycle life, especially with the growth of lithium dendrites, which hinder the development of high-energy density batteries.
Innovation Solution
An electrolyte comprising lithium difluoro(oxalate)borate (LiDFOB) at a concentration of 1.5 M to 3 M in a carbonate solvent, which facilitates smooth lithium plating and high cycling stability, even at elevated temperatures, thereby enhancing the performance of anode-free and lithium metal batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal is used as anode material to increase specific capacity, then energy density is improved, but mechanical properties deteriorate and reactivity increases leading to rapid capacity decay
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by using LiDFOB at concentrations of 1.5 M to 3 M, which fundamentally alters the electrolyte's interaction with lithium metal. This parameter change enables smooth lithium plating and stripping, resolving the contradiction between high specific capacity and poor cycle life by creating a stable electrochemical environment that accommodates lithium metal's high reactivity.
Solution Approach 2:
The patent employs a composite electrolyte system combining LiDFOB with carbonate solvents (cyclic and/or chain carbonates). This composite material approach creates synergistic effects where LiDFOB provides thermal stability and facilitates smooth lithium plating, while the carbonate solvents provide good ionic conductivity and solubility, together resolving the reliability issues of pure lithium metal anodes.
2Reliability
If lithium dendrites are suppressed to improve cycle life, then reliability is improved, but electrochemical impedance increases
Solution Approach 1:
The patent utilizes the specific concentration range of LiDFOB (1.5 M to 3 M) to optimize the electrolyte's properties. At these concentrations, the electrolyte achieves the right balance between suppressing lithium dendrite formation and maintaining low electrochemical impedance, as the high LiDFOB concentration promotes uniform lithium ion flux while the carbonate solvents ensure adequate ionic conductivity.
3Device complexity
If conventional electrolytes are used to maintain simplicity, then device complexity is reduced, but thermal stability deteriorates
Solution Approach 1:
The patent changes the chemical identity of the electrolyte salt from conventional options (like LiPF6) to LiDFOB, which inherently provides superior thermal stability. The carbonate solvent system is selected specifically for its thermal properties, creating a composition that maintains relative simplicity while dramatically improving thermal stability compared to conventional electrolytes.
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 achieves a capacity retention of 65% for anode-free batteries after 100 cycles and 70% for lithium metal batteries after 200 cycles, with improved thermal stability and reduced electrochemical impedance, enabling higher energy density and longer cycle life.
Implementation Method 1
The electrolyte as defined above may facilitate reversible and smooth lithium plating of the counter electrode on the anode side or the anode at an elevated temperature
Data Source
AI summary
The present invention relates to an electrolyte comprising lithium difluoro(oxalate)borate (LiDFOB) and a carbonate solvent, wherein LiDFOB is present at a concentration in the range of 1.5 M to 3 M, a rechargeable battery comprising the electrolyte as described herein, a cathode layer, an anode layer and a separator, and a method of preparing the electrolyte as described herein, comprising the step of dissolving LiDFOB in a carbonate solvent, wherein LiDFOB is present at a concentration in the range of 1.5 M to 3 M.