Nonaqueous Electrolyte Additives for Battery Safety
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Solution Overview
Problem
Nonaqueous-electrolyte secondary batteries face challenges with decreases in initial capacity and high-temperature storability, despite improved overcharge characteristics, and are unsatisfactory in terms of safety during overcharge.
Innovation Solution
Incorporating a compound represented by general formula (I) or (II) into the electrolytic solution, which includes an aryl group with a specific structure and an alkoxycarbonyloxy, organic sulfonate, or phosphoric acid ester group, to enhance safety during overcharge and high-temperature storability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aromatic compounds such as biphenyl, thiophene, and furan are incorporated into the electrolytic solution to protect the battery by increasing internal resistance, then safety during overcharge is improved, but initial capacity and high-temperature storability decrease
Solution Approach 1:
The patent changes the chemical structure parameters of the additive compounds, specifically using compounds with formula (I) containing aryl groups with specific substituents (alkoxycarbonyloxy, organic sulfonate, or phosphoric acid ester groups) and controlling the carbon atom number in substituent groups, to achieve both safety improvement and capacity maintenance
Solution Approach 2:
The patent employs composite electrolytic solutions containing multiple components: cyclic carbonate, chain carbonate, lithium salt, and the specific compound of formula (I), creating a composite system where each component contributes to overall performance including safety, capacity, and storability
2Reliability
If aromatic compounds such as biphenyl, thiophene, and furan are incorporated into the electrolytic solution to enable internal breaker to work without fail, then safety during overcharge is improved, but high-temperature storability decreases
Solution Approach 1:
The patent modifies molecular parameters of the additive by specifying formula (I) with controlled carbon atom numbers (R1 and R2 each independently represent a hydrogen atom, a halogen atom, or an optionally substituted hydrocarbon group having 1-12 carbon atoms) to reduce high-temperature degradation while maintaining overcharge protection
Solution Approach 2:
The patent uses small amounts (0.01-5% by weight) of the specific compound as a sacrificial protective layer that forms on the electrode surface, providing temporary protection during overcharge and high-temperature storage without significantly impacting long-term capacity
3Quantity of substance
If the active-material layer of an electrode is pressed and densified to minimize volume, then capacity is improved, but reactions proceed unevenly resulting in partial deposition of lithium and accelerated deterioration
Solution Approach 1:
The compound of formula (I) acts as an intermediary substance that forms a protective film on the electrode surface, mediating between the active material and electrolyte to ensure uniform lithium deposition and prevent deterioration while maintaining high capacity
4Quantity of substance
If the range over which a positive electrode is utilized is widened to use the positive electrode up to a higher potential, then capacity is improved, but deterioration is accelerated by the reaction between the positive electrode and the electrolytic solution
Solution Approach 1:
The compound of formula (I) performs preliminary action by forming a stable protective film on the positive electrode surface before high-potential operation begins, preventing direct harmful reactions between the electrode and electrolyte during extended charge-discharge 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 provides a nonaqueous-electrolyte battery with improved safety during overcharge and high-temperature storability, maintaining high capacity and performance in both portable and large-size applications.
Implementation Method 1
an additive that polymerizes at battery voltages higher than the maximum working voltage of batteries is incorporated into an electrolytic solution to thereby protect the battery by increasing the internal resistance thereof
Implementation Method 2
an additive that polymerizes at battery voltages higher than the maximum working voltage of batteries and that thereby evolves a gas to elevate the pressure is incorporated into an electrolytic solution to thereby enable an internal breaker disposed for protection from overcharge to work without fail
Data Source
AI summary
The present invention is to provide: a nonaqueous-electrolyte battery excellent in terms of safety during overcharge and high-temperature storability; and a nonaqueous electrolytic solution which gives the battery. The present invention relates to a nonaqueous electrolytic solution comprising an electrolyte and a nonaqueous solvent, wherein the nonaqueous electrolytic solution comprises at least one of specific compounds.