Electrolyte Composition for High-Voltage Battery Expansion Control
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Solution Overview
Problem
High-voltage electrochemical devices face issues with cathode material oxidizability and stability, leading to non-aqueous electrolyte decomposition and battery capacity reduction due to floating-charge phenomena, which affects their reliability and performance.
Innovation Solution
An electrolyte comprising a fluorinated cyclic carbonate and a multi-nitrile compound with an ether bond, where the weight percentage of the fluorinated cyclic carbonate is greater than the multi-nitrile compound, along with additional components like fluoroethers and cyclic phosphonic anhydrides, is used to stabilize the interface and control battery expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-voltage cathode materials are used to increase energy density, then energy density is improved, but cathode material oxidizability increases and stability decreases, causing electrolyte decomposition and capacity reduction
Solution Approach 1:
The patent introduces a film-forming additive as an intermediary substance between the high-voltage cathode material and the non-aqueous electrolyte. This additive preferentially reacts with the cathode material to form a stable interface film that acts as a protective barrier, preventing direct contact and harmful interactions between the electrolyte and cathode, thereby resolving the contradiction between achieving high energy density and maintaining cathode stability.
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by incorporating specific film-forming additives with particular functional groups. This parameter change transforms the interface properties, creating a more stable electrochemical environment that enables high-voltage operation without sacrificing cathode material stability, thus allowing both high energy density and reliability to be achieved.
2Duration of action of moving object
If floating charge is applied to maintain full charge state, then battery availability is improved, but thickness expansion occurs and capacity attenuation increases, reducing reliability
Solution Approach 1:
The patent applies preliminary action by having the film-forming additive react in advance during initial charging cycles to create a stable protective film on the cathode surface. This pre-formed film prevents subsequent thickness expansion and capacity attenuation during floating charge operations, allowing the battery to maintain full charge state for extended periods without degradation, thus improving both availability and reliability.
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 enhances the electrochemical device's cycle, storage, and floating-charge performance by suppressing thickness expansion and maintaining interface stability, thereby improving capacity retention and high-temperature storage performance.
Implementation Method 1
the oxidizability of the cathode material is increased, and the stability is lowered, which causes the non-aqueous electrolyte to easily decompose on the surface of the cathode
Implementation Method 2
The electrolyte of the present application can control the expansion of the electrochemical device, so that the electrochemical device has excellent cycle, storage and/or floating-charge performance
Data Source
AI summary
An electrolyte includes a fluorinated cyclic carbonate, a multi-nitrilemulti-nitrile compound having an ether bond and a compound having a sulfur-oxygen double bond. Based on a total weight of the electrolyte, a weight percentage (Cf) of the fluorinated cyclic carbonate is greater than a weight percentage (Cn) of the multi-nitrilemulti-nitrile compound having an ether bond. The electrolyte can control the expansion of the electrochemical device, so that the electrochemical device has excellent cycle, storage and/or floating-charge performance.