Aqueous Li-Ion Battery Anode Resin for Suppressing Water Electrolysis
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Solution Overview
Problem
Aqueous electrolyte batteries face challenges in achieving high energy density and efficient charge-and-discharge due to the narrow potential window of water, leading to limited charge-and-discharge ranges to prevent electrolysis.
Innovation Solution
A Li-ion secondary battery design incorporating a negative electrode with a titanium oxide or titanium-containing oxide active material, an additive resin containing a hydroxyl group unit and a butyral or acetal unit, and an aqueous electrolyte, which suppresses water electrolysis and enhances charge-and-discharge efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an aqueous electrolyte is used to improve safety by eliminating combustibility, then safety is improved, but the potential window is narrowed and energy density decreases
Solution Approach 1:
The invention changes the chemical parameters of the aqueous electrolyte by adding specific organic additives (cyclic carbonate esters with 3-12 carbon atoms) to modify the electrochemical window and interface properties, enabling operation at higher potentials while maintaining aqueous safety benefits
Solution Approach 2:
The invention creates a composite electrolyte system combining aqueous solvent with organic cyclic carbonate ester additives, leveraging the safety of water while incorporating the high-voltage stability of organic components to achieve both safety and energy density
2Reliability
If the charge-and-discharge range is limited to prevent water electrolysis, then safety is improved, but charge-and-discharge efficiency decreases
Solution Approach 1:
The organic cyclic carbonate ester acts as an intermediary substance that mediates between the aqueous electrolyte and electrode surfaces, forming protective interface layers that prevent water electrolysis while enabling efficient charge transfer at higher potentials
Solution Approach 2:
The invention changes the electrochemical parameters of the aqueous electrolyte system by introducing organic additives that shift the electrolysis potential window, allowing operation at higher voltages without water decomposition
3Quantity of substance
If the potential range is expanded to improve energy density, then energy density is improved, but water electrolysis occurs and safety deteriorates
Solution Approach 1:
The invention converts the harmful effect of water electrolysis into a beneficial outcome by using organic cyclic carbonate ester additives to form protective films that suppress water decomposition while enabling high-potential operation, thus achieving high energy density without safety compromise
Solution Approach 2:
The invention changes the electrochemical stability parameters of the aqueous electrolyte by adding organic components that expand the effective potential window, allowing high-energy-density operation without water electrolysis
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 battery achieves improved charge-and-discharge efficiency, reduced self-discharge, and extended lifespan by inhibiting water electrolysis and maintaining high hydrophobicity of the negative electrode.
Implementation Method 1
maintaining high hydrophobicity of the negative electrode
Implementation Method 2
inhibiting water electrolysis
Implementation Method 3
a compound whose lithium ion insertion/extraction potential is from 1 V (vs. Li/Li+) to 3 V (vs. Li/ Li+)
Implementation Method 4
an aqueous electrolyte obtained by dissolving an electrolyte salt in an aqueous solvent
Implementation Method 5
The nonaqueous electrolyte has high oxidation resistance and high reduction resistance, and electrolysis of the solvent hardly occurs
Data Source
Figure 1
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AI summary
According to one embodiment, there is provided a secondary battery including a positive electrode, a negative electrode, and an aqueous electrolyte. The positive electrode includes a positive electrode active material. The negative electrode includes a negative electrode active material and an additive resin containing a hydroxyl group unit and a first unit. The first unit consists of at least one of a butyral unit and an acetal unit. A content ratio of a content of the first unit contained in the additive resin to a content of the hydroxyl group unit contained in the additive resin is in a range of 1.2 to 18.