Lithium Battery Nickel Cathode Stabilization via Phosphonoacetate Additive
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Solution Overview
Problem
Lithium secondary batteries face issues with internal pressure increase, capacity reduction, and unstable nickel-based active materials at high temperatures, leading to poor storage and cycle characteristics, especially when using nickel-containing positive electrodes.
Innovation Solution
A lithium secondary battery design incorporating a positive electrode with a lithium-containing composite oxide containing nickel, a molar ratio of nickel to lithium between 0.05 and 1.0, and a nonaqueous electrolytic solution with 0.5 to 5.0 mass% of a phosphonoacetate-based compound, which stabilizes the battery and improves high-temperature storage and charge/discharge cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a nickel-containing positive active material is used to increase battery capacity, then battery capacity is improved, but internal pressure increases and storage characteristics deteriorate at high temperature
Solution Approach 1:
A phosphonoacetate-based compound is introduced as an intermediary substance in the electrolytic solution to mediate between the nickel-containing positive active material and the electrolyte. This compound forms a stable interface layer that prevents direct harmful reactions while allowing ionic transport, thereby maintaining high capacity benefits while suppressing high-temperature degradation and gas generation
Solution Approach 2:
The chemical composition parameters of the electrolytic solution are changed by incorporating a phosphonoacetate-based compound with specific molecular structure characteristics. This parameter change modifies the electrolyte's interaction with the nickel-containing cathode, stabilizing the interface and preventing the high-temperature side reactions that lead to gas generation and capacity loss
2Quantity of substance
If the upper limit voltage is set in a high-voltage region to increase capacity, then battery capacity is improved, but electrolytic solution decomposes and positive active material becomes unstable
Solution Approach 1:
The phosphonoacetate-based compound acts as a protective intermediary that forms a stable interfacial layer between the positive electrode and electrolyte. This layer remains stable at high voltages (4.3V or more), preventing electrolyte decomposition and cathode material instability while allowing the battery to operate in the high-voltage capacity region
3Quantity of substance
If nickel content in positive active material is increased to enhance capacity, then battery capacity is improved, but Ni becomes unstable at high temperature and forms side reaction products
Solution Approach 1:
The phosphonoacetate-based compound serves as a stabilizing intermediary that forms a protective interface layer around the nickel-containing cathode particles. This layer prevents direct contact between unstable nickel sites and the electrolyte, suppressing high-temperature side reactions while preserving the high-capacity nickel-based cathode composition
Solution Approach 2:
The potential harm of nickel instability at high temperature is converted into a benefit by using the phosphonoacetate compound to selectively form a stable interface layer. This layer exploits the nickel's high reactivity to create a protective barrier that prevents further degradation, transforming the instability problem into a controlled protective mechanism
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 enhances storage characteristics at high temperatures and maintains satisfactory charge and discharge cycle characteristics, even under high voltage, by stabilizing the nickel-based active material and reducing gas generation, thus extending battery life and capacity.
Implementation Method 1
a nonaqueous electrolytic solution contains 0.5 to 5.0 mass % of a phosphonoacetate-based compound... which stabilizes the battery and improves high-temperature storage and charge/discharge cycle performance
Data Source
AI summary
A lithium secondary battery of the present invention includes: a positive electrode; a negative electrode; a nonaqueous electrolytic solution; and a separator. The positive active material contains a lithium-containing composite oxide containing nickel. A molar ratio of a total nickel amount with respect to a total lithium amount contained in the entire positive active material is 0.05 to 1.0. The nonaqueous electrolytic solution contains 0.5 to 5.0 mass % of a phosphonoacetate-based compound represented by the following General Formula (1). In the Formula, R1, R2, and R3 independently represent an alkyl group, an alkenyl group, or an alkynyl group having 1 to 12 carbon atoms, which may be substituted by a halogen atom, and “n” represents an integer of 0 to 6.