Battery Electrolyte Composition for Volume-Changing High-Capacity Anodes
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Solution Overview
Problem
Conventional electrolytes perform poorly with high-capacity, micron-scale, volume-changing anode particles in rechargeable batteries, leading to poor cell performance and limited cycle stability, particularly when anode capacity loading is moderate to high and porosity or binder content is low.
Innovation Solution
Development of a specific electrolyte composition comprising low-melting point and regular-melting point solvents, along with appropriate metal-ion salts, to stabilize the anode and cathode electrodes, especially for high-capacity, micron-scale anode particles experiencing significant volume changes during cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional electrolytes are used with high-capacity, micron-scale anode particles, then cell energy density can be increased through high capacity loading, but cell performance and cycle stability deteriorate
Solution Approach 1:
The patent applies parameter changes by modifying the electrolyte composition parameters - specifically using a carbonate-rich solvent mixture (70-95 vol% carbonates) with particular ratios of cyclic to linear carbonates, and controlling salt concentration (0.5-2.0 M). These parameter adjustments optimize the electrolyte's interaction with high-capacity anode particles, enabling stable cycling at high capacity loadings (4-10 mAh/cm2) that would otherwise fail with conventional electrolytes.
Solution Approach 2:
The patent employs composite materials by combining multiple carbonate solvents (cyclic and linear) with specific metal-ion salts to create a composite electrolyte system. This composite approach leverages the complementary properties of different components - cyclic carbonates provide high dielectric constant for salt dissolution while linear carbonates provide low viscosity for ion mobility - achieving both high energy density and cycle stability simultaneously.
2Quantity of substance
If porosity of the anode is reduced to increase electrode density, then cell energy density improves, but cell performance deteriorates
Solution Approach 1:
The patent uses parameter changes by adjusting the electrolyte's physical parameters - specifically lowering viscosity through high linear carbonate content (30-70 vol%) and optimizing dielectric properties through cyclic carbonate selection. These parameter changes enable the electrolyte to effectively penetrate and wet dense electrode structures with low porosity (5-25 vol%), maintaining ion transport efficiency and cell performance despite reduced electrode porosity.
3Quantity of substance
If binder content in the electrode is reduced to increase energy density, then cell energy density improves, but cell performance and stability worsen
Solution Approach 1:
The patent applies parameter changes by modifying the electrolyte composition to create a more stable solid electrolyte interphase (SEI) through specific carbonate ratios and salt concentrations. This stabilized SEI compensates for reduced binder content (0.5-5 wt%), maintaining electrode structural integrity and cell stability even with minimal binder, thereby achieving high energy density without sacrificing reliability.
4Quantity of substance
If high-capacity anode particles with significant volume change are used, then specific capacity increases, but electrode structural stability deteriorates
Solution Approach 1:
The patent uses parameter changes by optimizing the electrolyte composition parameters - specifically the ratio of cyclic to linear carbonates (20-80:20-80 vol%) and salt concentration (0.5-2.0 M) - to form a flexible, stable SEI that can accommodate the 8-180 vol% volume expansion of high-capacity anode particles during cycling. This parameter optimization maintains electrode structural stability while enabling high specific capacity (550-2200 mAh/g).
Solution Approach 2:
The patent employs composite materials by creating a composite electrolyte system combining cyclic and linear carbonates with metal-ion salts. This composite structure forms a multi-component SEI that provides both mechanical flexibility to accommodate volume changes and chemical stability to maintain electrode integrity, enabling high-capacity anode particles to cycle stably despite significant expansion and contraction.
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 new electrolyte composition enhances cell stability, energy density, and rate performance by minimizing binder swelling and maintaining a stable solid electrolyte interphase, even with high-capacity anodes undergoing substantial volume changes.
Implementation Method 1
maintaining a stable solid electrolyte interphase
Implementation Method 2
an electrolyte ionically coupling the anode electrode and the cathode electrode
Implementation Method 3
The solvent composition comprises one or more low-melting point solvents that each have a melting point in the range from about −140° C. to about −60° C.
Implementation Method 4
minimizing binder swelling
Data Source
AI summary
In an embodiment, a metal-ion battery cell comprises an anode electrode, a cathode electrode, a separator, and electrolyte ionically coupling the anode electrode and the cathode electrode. The anode electrode is a high-capacity electrode (e.g., in the range of about 2 mAh/cm2 to about 10 mAh/cm2). The electrolyte includes a solvent composition, the solvent composition including low-melting point (LMP) solvent(s) in the range from about 10 vol. % to about 80 vol. % of the solvent composition as well as regular-melting point (RMP) solvent(s) in the range from about 20 vol. % to about 90 vol. % of the solvent composition.