Cyclic Carbonate Electrolytes for Stable Silicon Battery Interfaces
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-ion batteries with silicon-based anodes and high-voltage cathodes face challenges such as unstable solid electrolyte interphase (SEI) layers, irreversible capacity loss, and poor cycling stability due to volumetric expansion, as well as cathode instability and thermal issues with conventional electrolytes.
Innovation Solution
Development of electrolyte additives that form stable, electronically insulating yet ionically conductive SEI layers on silicon anodes and cathode-compatible CEI layers, using cyclic carbonate additives to enhance thermal stability and reduce flammability, along with self-supporting composite electrodes that eliminate metal current collectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based anodes are used to increase energy density, then capacity is improved, but volumetric expansion during lithiation leads to SEI layer instability and poor cycling life
Solution Approach 1:
The patent modifies the chemical composition parameters of the electrolyte by incorporating cyclic carbonate additives (1,3-dioxolan-2-one and 1,3-dioxolane-2,4-dione) with specific molecular structures. These additives change the physicochemical properties of the electrolyte, enabling formation of stable SEI layers that can accommodate silicon's volumetric expansion during cycling, thereby resolving the contradiction between high capacity and cycling stability.
Solution Approach 2:
The cyclic carbonate additives act as intermediary substances that mediate between the silicon anode and the conventional electrolyte. These additives preferentially decompose to form protective SEI layers that serve as intermediaries, preventing direct contact between the electrolyte and silicon surface, thus stabilizing the interface despite silicon's expansion and contraction during lithiation/delithiation cycles.
2Quantity of substance
If conventional electrolytes are used with high-voltage cathodes, then energy density is improved, but oxidative instability occurs beyond 4.5 V leading to accelerated decay
Solution Approach 1:
The patent changes the electrolyte's oxidation resistance parameters by introducing cyclic carbonate additives with specific molecular structures (1,3-dioxolan-2-one and 1,3-dioxolane-2,4-dione). These additives elevate the electrolyte's oxidative stability threshold, enabling safe operation at cathode potentials exceeding 4.5 V vs. Li/Li+, thus allowing high energy density to be achieved without sacrificing cycling stability.
3Quantity of substance
If silicon anodes are used to achieve high capacity, then energy density is improved, but thermal safety and flammability issues arise
Solution Approach 1:
The patent modifies the electrolyte's thermal and flammability parameters by incorporating cyclic carbonate additives. These additives alter the electrolyte's thermal decomposition behavior and reduce its flammability, thereby improving the thermal safety of silicon-based batteries while maintaining their high energy density advantages.
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
Improves cycling stability, thermal safety, and energy density of lithium-ion batteries by forming stable SEI and CEI layers, reducing flammability, and eliminating the need for metal current collectors.
Implementation Method 1
an unstable solid electrolyte interphase (SEI) layer can develop on the surface of the cycled anodes
Implementation Method 2
an endless exposure of Si particle surfaces to the liquid electrolyte. This results in an irreversible capacity loss at each cycle due to the reduction at the low potential where the liquid electrolyte reacts with the exposed surface of the Si anode
Implementation Method 3
the ideal additives should be oxidized preferentially to the solvent molecule in the bare electrolyte, resulting in a protective cathode electrolyte interphase (CEI) film formed on the surface of the Ni-rich NCM (or NCA) and LCO cathodes
Implementation Method 4
the ideal additives should be oxidized preferentially to the solvent molecule in the bare electrolyte
Implementation Method 5
using cyclic carbonate additives to enhance thermal stability and reduce flammability
Data Source
AI summary
Electrolytes and electrolyte additives for use in energy storage devices, comprising cyclic carbonate compounds.