Sacrificial Electrode Design for Low-Voltage Battery Discharge
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Solution Overview
Problem
Metal ion battery cells, such as lithium ion batteries, are susceptible to internal morphological deformations and safety hazards due to parasitic reactions during charging and discharging, leading to capacity loss and potential safety risks when exposed to low or zero-voltage states.
Innovation Solution
Incorporating a sacrificial electrode with a lower decomposition voltage than the negative current collector, which decomposes instead of the current collector when the battery is discharged to low or zero-voltage, thereby preserving the battery's morphology and preventing dendrite formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the battery is discharged to low or zero-voltage states, then the energy capacity is maximized, but internal morphological deformations and dendrite formation occur causing safety hazards and capacity loss
Solution Approach 1:
The sacrificial electrode is pre-installed in the battery cell to proactively prevent damage to the negative current collector. Before the negative current collector can undergo harmful parasitic reactions at low voltages, the sacrificial electrode is already positioned to decompose first, thereby protecting the structural integrity of the battery cell during subsequent low-voltage discharge events.
Solution Approach 2:
The sacrificial electrode is designed as a consumable component with lower decomposition voltage than the negative current collector. It intentionally sacrifices itself through decomposition at low voltages, converting a potentially harmful effect into a controlled, replaceable event. This disposable approach protects the more valuable and structurally critical negative current collector from degradation.
2Reliability
If a sacrificial electrode is added to protect the negative current collector, then reliability and safety are improved, but device complexity increases
Solution Approach 1:
The sacrificial electrode serves multiple functions simultaneously: it acts as an active electrode during normal charge-discharge cycles contributing to capacity, and serves as a protective sacrificial layer during low-voltage conditions. This multi-functionality justifies the added component by providing both energy storage and protection roles within a single element.
3Stability of the object's composition
If the sacrificial electrode decomposes instead of the negative current collector, then the negative current collector structure is preserved, but the sacrificial electrode material is consumed
Solution Approach 1:
The sacrificial electrode material is intentionally discarded through controlled decomposition at low voltages, protecting the negative current collector from similar degradation. The decomposed sacrificial material can be recovered during subsequent charging cycles or through material regeneration processes, converting the loss into a manageable and potentially reversible event.
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 sacrificial electrode effectively maintains the battery's capacity and cycle life even when discharged to low or zero-voltage states, reducing the risk of internal short circuits and enhancing long-term storage stability.
Implementation Method 1
the sacrificial electrode decomposes instead of the negative current collector while the battery cell is discharged below a minimum voltage of the battery cell
Data Source
AI summary
A battery cell may include a positive electrode coupled with a positive current collector and a negative electrode coupled with a negative current collector. The battery cell may further include a sacrificial electrode coupled with the negative electrode but not the positive electrode. The sacrificial electrode may be formed from a first material having a lower decomposition voltage than a second material forming the negative current collector. As such, the sacrificial electrode may decompose instead of the negative current collector while the battery cell is discharged below a minimum voltage of the battery cell. In doing so, the sacrificial electrode may preserve the capacity and cycle life of the battery cell even when the battery cell is discharged to a low-voltage state or a zero-voltage state.