Battery Pre-Lithiation Control for Silicon Anode Formation Loss

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Solution Overview

Problem

The use of silicon anodes in lithium-based secondary batteries is limited due to large volumetric changes, cracking, and pulverization during charge and discharge cycles, as well as poor initial columbic efficiency, leading to capacity loss during battery formation.

Innovation Solution

A method and system for pre-lithiating lithium-based secondary batteries using an auxiliary electrode containing lithium metal, where a current sink is used to diffuse lithium from the auxiliary electrode to the electrode active material layers, and a pre-lithiation module controller adjusts the voltage and current to ensure efficient lithium distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If silicon anodes are used to replace carbonaceous materials, then specific capacity is improved (nearly 10-fold increase), but volumetric changes and structural stability deteriorate (300% volumetric increase, cracking, and pulverization)

Engineering Contradiction:

Improvespecific capacityVSAvoidstructural stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent applies flexible shell concepts by using a polymer coating layer that can accommodate the volumetric expansion and contraction of silicon anodes during charge-discharge cycles. This flexible polymer shell prevents structural failure by allowing controlled deformation without cracking, thus maintaining the integrity of the anode structure while enabling high capacity silicon to be used effectively.

Inventive Principle:

Principle #30Flexible shells and thin films

2Quantity of substance

If silicon anodes are used, then specific capacity is improved, but initial columbic efficiency deteriorates (poor ICE leading to capacity loss during formation)

Engineering Contradiction:

Improvespecific capacityVSAvoidinitial columbic efficiency

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-coating the silicon anode with a polymer layer before battery assembly and formation cycling. This pre-formed protective shell is designed to maintain structural integrity during the initial formation process, preventing excessive pulverization and capacity loss. The preliminary protective action enables the silicon anode to achieve better initial columbic efficiency while retaining its high capacity potential.

Inventive Principle:

Principle #10Preliminary action

3Extent of automation

If large centralized formation systems are used, then formation process control is improved, but system complexity and space requirements worsen (large control centers, significant power consumption, extensive wiring)

Engineering Contradiction:

Improveformation process controlVSAvoidsystem complexity

Core Design Contradiction:

Extent of automationVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the centralized formation system into multiple distributed modular units, each capable of independently controlling formation processes for groups of batteries. This modular architecture reduces overall system complexity by eliminating the need for a single large control center, distributes power consumption across multiple smaller units, and reduces wiring requirements by enabling localized control. Each module can autonomously manage formation parameters, maintaining effective control while significantly reducing system-level complexity.

Inventive Principle:

Principle #1Segmentation

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 proposed method improves the initial columbic efficiency and capacity retention of silicon-based anodes by maintaining additional carrier ions post-formation, reducing cycle-by-cycle capacity loss, and enhancing the cycling performance of the battery.

Implementation Method 1

controlling the current sink to conduct a current from the electrode busbar through the auxiliary electrode to diffuse lithium from the auxiliary electrode to the electrode active material layers

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 2

periodically detecting a voltage between the auxiliary electrode and counter-electrode busbar

Methodology Applied

Scientific EffectVoltage detection: Electric Field

Data Source

PatentUS20250105246A1Cell formation methods and systems for lithium based secondary batteries

Publication Date: 2025.03.27 ENOVIX CORP

AI summary

A method of pre-lithiating a lithium based secondary battery. The battery includes a population of unit cells, an electrode busbar, and a counter-electrode busbar. Each unit cell includes an electrode structure, a separator structure, and a counter-electrode structure. An auxiliary electrode containing lithium metal is connected to the unit cells. A current sink is connected to the electrode busbar and the auxiliary electrode, the current sink is controlled to conduct current from the electrode busbar through the auxiliary electrode, a voltage between the auxiliary electrode and counter-electrode busbar is detected periodically, an adjustment to the voltage is determined periodically, and the current sink is controlled to control an amplitude of the current to cause a sum of the voltage and the adjustment to be about zero volts.