Battery Compression Fixture for Silicon Anode Formation
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Solution Overview
Problem
The use of silicon anodes in lithium-containing secondary batteries is limited due to large volumetric changes, cracking, and poor initial columbic efficiency, leading to capacity loss and requiring centralized, expensive formation systems for battery formation.
Innovation Solution
A distributed cell formation process using a compression fixture with a loading mechanism and an auxiliary anode to mitigate initial carrier ion loss and improve cycling performance, allowing for decentralized and scalable battery formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon anodes are used to replace carbonaceous materials, then specific capacity increases nearly 10 fold, but volumetric changes of 300% occur during charge and discharge cycles
Solution Approach 1:
The patent employs a flexible pouch encapsulating the silicon anode, allowing the anode structure to expand and contract during lithium insertion/extraction cycles. The pouch acts as a compliant container that accommodates the 300% volumetric changes without causing mechanical failure, while maintaining structural integrity throughout charge-discharge cycles.
Solution Approach 2:
The patent uses composite electrode structures where silicon anode material is combined with other materials (such as carbonaceous materials or binders) to create a composite electrode. This composite structure provides both the high capacity benefits of silicon and the structural stability needed to accommodate volumetric changes, reducing cracking and pulverization.
2Quantity of substance
If silicon anodes are used, then specific capacity increases, but initial columbic efficiency deteriorates leading to capacity loss
Solution Approach 1:
The patent implements a pre-lithiation process where lithium is added to the battery during the formation process before normal operation begins. This preliminary action compensates for the lithium that will be irreversibly consumed during initial cycles, thereby improving the initial columbic efficiency and reducing capacity loss.
Solution Approach 2:
The patent introduces an auxiliary anode as an intermediary element that facilitates lithium transfer during the formation process. This auxiliary anode acts as a mediator to improve the initial columbic efficiency by providing additional lithium that can be transferred to the silicon anode during controlled formation cycles.
3Extent of automation
If centralized formation systems are used to control charging and discharging of batteries, then formation process can be controlled, but system size, cost, and power consumption increase significantly
Solution Approach 1:
The patent divides the formation system into distributed modular units, each capable of independently controlling formation processes for individual or small groups of batteries. This segmentation eliminates the need for a single large centralized control system, reducing overall system size, complexity, and power consumption while maintaining automated formation control.
Solution Approach 2:
The patent implements formation control at the battery pack level, where each pack or module manages its own formation process autonomously. This self-service approach allows batteries to perform formation operations locally without requiring constant communication with or control from a central system, thereby reducing system complexity and wire requirements.
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 solution enhances the capacity and cycling performance of silicon-based anodes by maintaining lower anode potential during discharge and increasing energy density, while reducing the need for large centralized control systems.
Implementation Method 1
at least one spring operatively coupled to the moveable compression plate. The moveable compression plate is positioned farther from the fixed compression plate in a second position than in a first position. The at least one spring biases the moveable compression plate towards the fixed compression plate such that a compressive force is applied to the lithium containing secondary battery
Data Source
AI summary
A compression fixture includes a base and a plurality of compression plate sets coupled to the base. Each compression plate set includes a fixed compression plate, a moveable compression plate, and at least one spring coupled to the moveable compression plate. The moveable compression plate is moveable relative to the fixed compression plate between a first position and a second position in which the moveable compression plate is positioned farther from the fixed compression plate than in the first position. The fixed compression plate and the moveable compression plate define a battery receptacle therebetween for receiving a lithium containing secondary battery. The at least one spring biases the moveable compression plate towards the fixed compression plate such that a compressive force is applied to the lithium containing secondary battery when positioned within the battery receptacle. The compression fixture may be incorporated into a cell formation system for lithium containing secondary batteries.