Prelithiated Si-Ge-Sn Anodes for Fast Charging Cells

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Solution Overview

Problem

Conventional lithium ion batteries are either energy dense or power dense but struggle to achieve both simultaneously while maintaining a long cycling lifetime, especially when fast charging is required.

Innovation Solution

The solution involves prelithiating anodes with Si, Ge, or Sn to a high lithium content, optimizing the electrolyte, and adjusting the cathode to anode (C/A) ratio to achieve a balance between energy density and cycling lifetime, allowing for fast charging capabilities without compromising performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the anode is prelithiated to high lithium content to increase energy density, then the energy density is improved, but the cycling lifetime deteriorates due to anode instability

Engineering Contradiction:

Improveenergy densityVSAvoidcycling lifetime

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The anode is prelithiated before cell assembly by forming a lithium-rich precursor structure through controlled lithiation of Si/Ge/Sn particles. This preliminary action ensures the anode contains excess lithium that will be gradually consumed during cycling, preventing anode degradation while maintaining high energy density. The prelithiation state is achieved by controlling parameters such as lithium precursor concentration and formation cycle conditions.

Inventive Principle:

Principle #10Preliminary action

2Power

If the C/A ratio is reduced to optimize fast charging performance, then the power density is improved, but the energy density deteriorates

Engineering Contradiction:

Improvepower densityVSAvoidenergy density

Core Design Contradiction:

PowerVSUse of energy by moving object

Solution Approach 1:

The C/A ratio is optimized by adjusting cathode or anode active material loading to achieve a specific range (0.7-1.3) that balances power and energy density. This parameter change allows the cell to accept high charging rates while maintaining adequate energy storage. The optimal C/A ratio is determined based on the specific anode composition and prelithiation level.

Inventive Principle:

Principle #35Parameter changes

3Use of energy by moving object

If Si/Ge/Sn content in the anode is increased to achieve high capacity, then the energy density is improved, but the anode stability during cycling deteriorates

Engineering Contradiction:

Improveenergy densityVSAvoidanode stability

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The anode is constructed as a composite material system combining Si/Ge/Sn particles with carbon matrix and conductive additives. This composite structure provides high capacity from the Si/Ge/Sn while the carbon matrix maintains structural integrity and electrical conductivity during cycling. The composite approach allows achieving >20 wt% Si/Ge/Sn content while maintaining anode stability through the synergistic combination of high-capacity and structurally-stable materials.

Inventive Principle:

Principle #40Composite materials

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

This approach enables lithium ion batteries to achieve both high energy and power density while supporting prolonged cycling lifetimes, even under fast charging conditions, by stabilizing the anode and reducing electrolyte loss, thus enhancing overall battery performance.

Implementation Method 1

prelithiating at least one anode of a fast charging cell to reach a lithium content determined by an anode content of at least one of Si, Ge and Sn, anode capacity loss during formation and a required cycling lifetime

Methodology Applied

Scientific EffectPrelithiation:

Implementation Method 2

optimizing an electrolyte of the cell to increase cycling lifetime

Methodology Applied

Scientific EffectIon transport:

Implementation Method 3

fast charging lithium ion cell

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Data Source

PatentUS11658279B2Method for configuring and prelithiating a fast charging cell

Publication Date: 2023.05.23 STOREDOT

AI summary

Prelithiation methods and fast charging lithium ion cell are provided, which combine high energy density and high power density. Several structural and chemical modifications are disclosed to enable combination of features that achieve both goals simultaneously in fast charging cells having long cycling lifetime. The cells have anodes with high content of Si, Ge and/or Sn as principal anode material, and cathodes providing a relatively low C/A ratio, with the anodes being prelithiated to have a high lithium content, provided by a prelithiation algorithm. Disclosed algorithms determine lithium content achieved through prelithiation by optimizing the electrolyte to increase cycling lifetime, adjusting energy density with respect to other cell parameters, and possibly reducing the C/A ratio to maintain the required cycling lifetime.