Li-ion Battery with LiF Electrolyte and Anion Receptor
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Solution Overview
Problem
Current lithium-ion batteries face challenges with high specific energy requirements due to stress-induced degradation of graphite electrodes from large anion insertion and deinsertion, leading to capacity loss and limited rate capability, and the use of LiF is hindered by its insolubility in organic solvents and high redox potential.
Innovation Solution
The development of high voltage and high specific energy Li-ion batteries utilizing LiF as the electrolyte salt, with an anion receptor to enhance solubility and conductivity, and dual intercalating carbonaceous electrodes to facilitate reversible ion intercalation without electrode degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large anions (e.g., PF6−) are used in the electrolyte, then ionic conductivity is improved, but graphite electrode degradation occurs due to stress from insertion and deinsertion
Solution Approach 1:
The patent changes the key parameter of anion size from large (PF6−, 0.45 nm) to small (F−, 0.136 nm). This parameter change allows the anion to fit within the graphite interlayer spacing without causing stress-induced degradation, while still maintaining adequate ionic conductivity for battery operation.
Solution Approach 2:
The patent introduces LiF as an intermediary substance in the electrolyte that provides small F− anions. These anions act as a mediator that can move between electrodes without causing the mechanical stress problems associated with larger anions, thus protecting the graphite electrode integrity while enabling ion transport.
2Reliability
If LiF is used as electrolyte salt, then electrochemical stability and voltage are improved, but solubility in organic solvents deteriorates
Solution Approach 1:
The patent creates a composite electrolyte system combining LiF salt with organic solvents and cyclic carbonate additives. This composite approach allows LiF to dissolve in the organic solvent mixture, achieving both the electrochemical stability of LiF and the solubility needed for practical battery operation.
Solution Approach 2:
The patent changes the solvent parameters by using mixed solvent systems with cyclic carbonate additives instead of pure organic solvents. This parameter change in solvent composition enables LiF to achieve adequate solubility while maintaining the desired electrochemical stability and conductivity properties.
3Use of energy by moving object
If dual intercalating electrodes are used, then specific energy is improved, but electrode degradation accelerates due to repeated insertion stresses
Solution Approach 1:
The patent changes the parameter of anion size to small F− ions that can intercalate into graphite electrodes without causing the mechanical stress and exfoliation problems associated with larger anions. This enables dual intercalating electrodes to achieve high specific energy while maintaining electrode integrity over many cycles.
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 solution achieves a greater than three-fold increase in specific energy, maintaining graphitic cathode function over many charge/discharge cycles, and provides safer, more environmentally friendly, and cost-effective battery systems with improved operating voltage and capacity.
Implementation Method 1
an anion receptor for increasing the ionic disassociation of LiF
Implementation Method 2
dual intercalating carbonaceous electrodes to facilitate reversible ion intercalation
Implementation Method 3
Li ions, which are transported from the anode to the cathode during discharge, and vice versa during charge
Data Source
AI summary
The present invention provides high capacity and high voltage Li-ion batteries that have a carbonaceous cathode and a nonaqueous electrolyte solution comprising LiF salt and an anion receptor that binds the fluoride ion. The batteries can comprise dual intercalating electrode Li ion batteries. Methods of the present invention use a cathode and electrode pair, wherein each of the electrodes reversibly intercalate ions provided by a LiF salt to make a high voltage and high specific capacity dual intercalating electrode Li-ion battery. The present methods and systems provide high-capacity batteries particularly useful in powering devices where minimizing battery mass is important.