Non-Aqueous Battery Electrolyte Using Anhydrosugar SEI Additives
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Solution Overview
Problem
Lithium secondary batteries with electrolyte liquids containing phosphonate and/or sulfonate additives have insufficient rate of maintaining life cycle at repeated charge/discharge.
Innovation Solution
A non-aqueous electrolyte composition for lithium secondary batteries, comprising electrolyte solvent, lithium salt, and an anhydrosugar alcohol derivative component (diester or diether) in specific amounts, which forms a stable SEI layer without the need for separate additives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If phosphonate and/or sulfonate additives are used in electrolyte liquid, then initial charge capacity is improved, but life cycle maintenance rate deteriorates
Solution Approach 1:
The patent changes the chemical structure parameter of the additive by using anhydrosugar alcohol derivatives (specifically isosorbide diesters or diethers) instead of conventional phosphonate or sulfonate additives. This structural parameter change results in both improved initial charge capacity and significantly improved life cycle maintenance rate, resolving the contradiction between initial performance and long-term stability.
Solution Approach 2:
The patent employs composite electrolyte liquid comprising multiple components: cyclic carbonate (10-40 vol%), chain carbonate (50-85 vol%), and anhydrosugar alcohol derivative (0.1-5 vol%). This composite formulation synergistically combines the high dielectric constant of cyclic carbonate, the low viscosity of chain carbonate, and the SEI-forming capability of the anhydrosugar alcohol derivative, achieving both high initial capacity and excellent life cycle maintenance.
2Reliability
If conventional electrolyte additives are used, then SEI layer formation is achieved, but storage stability deteriorates
Solution Approach 1:
The patent modifies the additive structure by selecting anhydrosugar alcohol derivatives with specific molecular characteristics (derived from sorbitol or mannitol, with specific ester or ether groups). These parameter changes in molecular structure enable the formation of stable SEI layers that also provide excellent storage stability, simultaneously improving both reliability and compositional stability.
Solution Approach 2:
The anhydrosugar alcohol derivative acts as an intermediary substance that mediates between the electrode and the bulk electrolyte. It forms a protective SEI layer that prevents direct contact and harmful reactions between the electrode and electrolyte, while its specific molecular structure ensures long-term storage stability. This intermediary function resolves the contradiction between SEI formation and storage stability.
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 composition improves the life cycle property and storage stability of lithium secondary batteries by inhibiting chemical reactions between electrodes and electrolyte, even without additional SEI-forming additives.
Implementation Method 1
At the initial charge of lithium secondary battery, an irreversible reaction is conducted wherein the charge is used excessively by the side reaction between the anode/cathode and the electrolyte liquid. Due to the side reaction, a passivation layer such as Solid-Electrolyte Interphase (SEI) layer is formed on the surface of the anode
Implementation Method 2
At the charge/discharge of the battery, the SEI layer inhibits decomposition of the electrolyte liquid and plays a role of ion tunnel
Implementation Method 3
a non-aqueous organic solvent containing dissolved lithium salt is used therefor, instead of an aqueous electrolyte having high reactivity with lithium
Data Source
AI summary
The present invention relates to: a non-aqueous electrolyte composition for a lithium secondary battery, comprising an anhydrosugar alcohol derivative; and a lithium secondary battery including same and, more specifically, to: a non-aqueous electrolyte composition comprising a specific amount of an anhydrosugar alcohol derivative as an additive and being capable of providing a lithium secondary battery having an improved battery lifespan property and storage stability; and a lithium secondary battery including same.