Lithium Reservoir Electrode for Rechargeable Battery Capacity Management
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Solution Overview
Problem
Lithium-ion batteries experience capacity fade due to side reactions, which existing methods like the use of an auxiliary lithium electrode are unable to effectively address without risking safety and degrading the cell, especially in applications where the battery orientation is not fixed.
Innovation Solution
A lithium-ion battery system with a lithium reservoir electrode (LRE) that acts as a reference electrode to measure the state of charge of working electrodes, allowing controlled lithium transfer to replenish lost capacity while maintaining uniform current distribution and preventing excessive lithium deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If an auxiliary lithium electrode is used to compensate for lithium loss, then battery capacity is replenished, but lithium transfer cannot be precisely controlled leading to excessive lithium deposition and safety risks
Solution Approach 1:
The patent employs a reference electrode to continuously monitor the state of charge of the auxiliary lithium electrode and working electrodes. This feedback mechanism enables the battery management system to precisely control when and how much lithium transfers from the auxiliary electrode to the working electrodes, preventing excessive lithium deposition while ensuring adequate capacity replenishment.
Solution Approach 2:
The reference electrode acts as an intermediary measurement tool that provides real-time information about the electrochemical state of the battery components. This intermediary enables indirect control of lithium transfer by measuring potential differences and providing data to the management system, which then regulates the transfer process to maintain safety.
2Duration of action of moving object
If an auxiliary lithium electrode is used to replenish lithium, then capacity fade is compensated, but the system becomes complex requiring additional electrodes and isolation mechanisms
Solution Approach 1:
The reference electrode serves multiple functions: it monitors the state of charge of the auxiliary lithium electrode, measures the state of charge of the working electrodes, and provides data for controlling lithium transfer. This multi-functionality reduces the need for separate monitoring systems and simplifies the overall structure compared to using multiple dedicated sensors.
Solution Approach 2:
The auxiliary lithium electrode automatically provides lithium compensation when needed, with the transfer process self-regulated by the potential differences measured by the reference electrode. The system uses its own electrochemical properties to control the replenishment process without requiring external intervention or complex control mechanisms.
3Reliability
If ionic isolation is used to control lithium transfer, then auxiliary electrode isolation is achieved, but electrolyte residual on separator ports allows unintended lithium transfer
Solution Approach 1:
The reference electrode provides continuous feedback on the state of charge of all electrodes, enabling the battery management system to detect and respond to unintended lithium transfer. When excess lithium transfer occurs through the separator, the feedback mechanism identifies the change in electrode states and can trigger corrective actions to restore proper balance.
4Ease of operation
If cell reorientation is used to enable lithium transfer, then auxiliary electrode connectivity is controlled, but applications with variable orientation cannot utilize this mechanism
Solution Approach 1:
The patent replaces the mechanical reorientation mechanism with an electrochemical control system. Instead of physically changing the battery orientation to control electrode connectivity, the system uses electrochemical potentials measured by the reference electrode to regulate lithium transfer electronically, making the solution applicable to batteries in any orientation.
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 system effectively replenishes lost capacity, enhances battery life by controlling lithium transfer, and maintains safety by preventing lithium deposition, making it suitable for various orientations and applications.
Implementation Method 1
uses the additionally provided lithium reservoir electrode (LRE) as a reference electrode to measure the open-circuit potential (OCP) of each working electrode thereby making known the state of charge (SOC) of each electrode
Implementation Method 2
replenishment of lithium to the depleted working electrode does not occur until the cell is reoriented such that the electrolyte is in contact with both the working electrode and the auxiliary electrode
Implementation Method 3
the porous separator could act as a wick to transport the electrolyte to the region of the separator that contacts the auxiliary electrode
Implementation Method 4
Such lithium deposition may pose a safety risk and/or degrade the cell because the lithium metal reacts rapidly and exothermically with the organic solvent used in the electrolyte
Data Source
AI summary
A lithium-ion battery cell includes at least two working electrodes, each including an active material, an inert material, an electrolyte and a current collector, a first separator region arranged between the at least two working electrodes to separate the at least two working electrodes so that none of the working electrodes are electronically connected within the cell, an auxiliary electrode including a lithium reservoir, and a second separator region arranged between the auxiliary electrode and the at least two working electrodes to separate the auxiliary electrode from the working electrodes so that none of the working electrodes is electronically connected to the auxiliary electrode within the cell.