Disulfonic Ester Electrolyte Additive for Manganese Elution Control
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Solution Overview
Problem
Nonaqueous secondary batteries using manganese-containing lithium transition metal oxide salts face issues with manganese elution during high-temperature storage and charge/discharge cycles, leading to increased internal resistance and reduced capacity.
Innovation Solution
A nonaqueous electrolyte containing a specific compound represented by general formula (1) is used, which includes a lithium salt dissolved in an organic solvent, featuring a group with sulfur and oxygen atoms, and specific hydrocarbon groups to prevent manganese elution and maintain low internal resistance and high electrical capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If manganese-containing lithium transition metal oxide salt is used as positive electrode active material, then battery capacity and power are improved, but manganese elution occurs during high-temperature storage and charge/discharge cycles causing increased internal resistance and reduced capacity
Solution Approach 1:
A disulfonic ester compound is introduced as an intermediary substance in the nonaqueous electrolyte. This compound acts as a mediator that preferentially reacts with eluted manganese ions to form stable complexes, preventing manganese deposition on the negative electrode and subsequent capacity fade. The disulfonic ester serves as a chemical trap for manganese ions, resolving the contradiction between using high-capacity manganese-based cathodes and maintaining long-term stability.
Solution Approach 2:
The disulfonic ester compound is used in small amounts (0.01-5 mass%) as a sacrificial additive that consumes eluted manganese ions. Rather than attempting to prevent manganese elution at the source, the system uses a small quantity of this additive to continuously scavenge manganese ions as they are released, effectively managing the degradation process without requiring fundamental changes to the high-capacity cathode material.
2Reliability
If conventional electrolyte additives are used to prevent manganese elution, then battery stability is improved, but internal resistance increases and electrical capacity deteriorates
Solution Approach 1:
The invention changes the chemical parameters of the electrolyte additive by selecting a disulfonic ester compound with specific molecular structure and functional groups. This compound exhibits optimal balance between manganese-chelating ability and electrochemical stability, achieving effective manganese suppression without forming resistive films on the electrodes. The specific structural parameters of the disulfonic ester (sulfonic acid groups, carbon chain length) are optimized to maintain high ionic conductivity while preventing manganese elution.
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 effectively prevents manganese elution, maintaining low internal resistance and high electrical capacity even under high-temperature conditions and during repeated charge/discharge cycles, enhancing the performance of nonaqueous secondary batteries.
Implementation Method 1
it having been found that this problem can be solved by using a nonaqueous electrolyte containing a specific compound
Implementation Method 2
These additive compounds are considered to form a stable film called a solid electrolyte interface covering the surface of the negative electrode, which film is expected to prevent reductive decomposition of the electrolyte
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a nonaqueous secondary battery having a nonaqueous electrolyte containing a lithium salt dissolved in an organic solvent, in which the positive electrode active material is preferably a manganese-containing, lithium transition metal oxide salt. The nonaqueous electrolyte of the invention contains at least one compound of general formula (1), preferably at least one compound of general formula (1'). The content of the compound of formula (1) or (1') in the nonaqueous electrolyte is preferably 0.001 to 10 mass%. The symbols in formulae (1) and (1') are as defined in the description.