Lithium Boron Fluoride Electrolyte for Low-Resistance Battery Cycling
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Solution Overview
Problem
Existing nonaqueous electrolytic solutions for lithium-ion secondary batteries face challenges in improving conductivity, maintaining high capacity after repeated charge and discharge cycles, reducing initial resistance, and retaining high performance at high temperatures, while aqueous and all-solid-state batteries require advancements in electrolytes to enhance solubility and stability.
Innovation Solution
A novel electrolyte and reinforcing agent containing specific complex compounds, such as those represented by Formula (1), are developed to enhance solubility in organic solvents, improve charge-discharge efficiency, and maintain resistance and high-temperature characteristics, using a method involving a binding reaction between boron halide-based salts and phosphorus compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolytes such as LiBF4 or LiPF6 are used in nonaqueous electrolytic solutions, then high conductivity and stable high voltage are achieved, but improvements in solubility, initial resistance characteristics, and high-temperature performance are insufficient
Solution Approach 1:
The patent employs composite electrolyte materials combining boron halide-based salts with phosphorus compounds containing P=O or P=S groups. This composite approach creates complex compounds that simultaneously improve solubility in organic solvents, enhance initial resistance characteristics, and maintain high-temperature stability, resolving the contradiction between reliability improvement and composition complexity by designing integrated multifunctional compounds rather than simple mixtures
Solution Approach 2:
The invention modifies the chemical parameters of the electrolyte by introducing specific functional groups (P=O, P=S) and varying the structural parameters of the phosphorus compound backbone. These parameter changes in molecular structure directly improve solubility and electrochemical performance without requiring complex multi-component systems, thus improving reliability while controlling composition complexity
2Reliability
If the conductivity of lithium ions is increased to lower electrical resistance, then charge-discharge efficiency improves, but maintaining low resistance at high temperatures and during cycling becomes difficult
Solution Approach 1:
The patent employs sacrificial phosphorus-containing compounds that form protective surface films on electrodes during initial cycles. These compounds decompose preferentially to create stable solid electrolyte interphase (SEI) layers that prevent further decomposition and maintain low resistance. The sacrificial nature of these compounds allows them to 'die' early to protect the main electrolyte system, ensuring long-term resistance stability at high temperatures
Solution Approach 2:
The electrolyte composition is designed to perform preliminary surface treatment on the electrodes during initial charging cycles. The phosphorus-containing compounds react with electrode surfaces beforehand to form protective coatings that stabilize the interface. This preliminary action prevents subsequent resistance increases during high-temperature operation and cycling, maintaining low resistance characteristics without requiring continuous intervention
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 novel electrolyte and reinforcing agent improve solubility, charge-discharge efficiency, and resistance values, while maintaining capacity retention and high-temperature stability in power storage devices.
Implementation Method 1
a nonaqueous electrolytic solution including an electrolyte, such as LiBF4 or LiPF6, dissolved is known to have high conductivity that indicates the transport of lithium ions
Implementation Method 2
using a method involving a binding reaction between boron halide-based salts and phosphorus compounds
Data Source
AI summary
The present invention addresses the problem of providing: an electrolyte that can be used to produce a power storage device and has an excellent balance between solubility in organic solvents (non-aqueous solvents), charge/discharge efficiency, −10° C. resistance value, cycle characteristics (volume change rate, capacity retention rate, resistance change rate), and high-temperature characteristics; a reinforcing agent; an electrolyte solution; a power storage device produced using the same; and a method for producing a lithium boron fluoride complex compound and a lithium complex compound for an electrolyte or a reinforcing agent. This electrolyte for a power storage device contains a lithium boron fluoride complex compound having a specific substituent.