Li-Ion Battery Cell Management for Dendrite Mitigation
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Solution Overview
Problem
Lithium-ion batteries with metal anodes face issues of dendrite formation and uneven morphology changes due to asymmetric charging and discharging rates, leading to potential internal shorts and runaway reactions.
Innovation Solution
A battery system with a processor-controlled electrochemical cell management system that implements a symmetrical charge and discharge profile by selectively connecting and disconnecting electrochemical cells based on target discharge rates to mitigate morphology changes and prevent dendrite formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal negative electrode is used to achieve high energy density, then energy density is improved, but dendrite formation and morphology changes occur leading to reduced reliability
Solution Approach 1:
The patent implements periodic action by alternating between charging and discharging phases with controlled durations. The charging phase deposits lithium ions onto the negative electrode, while the subsequent discharging phase removes them, preventing continuous accumulation that would cause dendrite formation. This periodic cycle maintains lithium metal integrity while preserving high energy density benefits.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting charging and discharging rates based on cell state. The controller modifies current parameters during operation to optimize lithium ion deposition and removal rates, preventing morphology changes and dendrite formation while maintaining high energy density operation.
2Speed
If asymmetric charging and discharging rates are applied to achieve rapid charging, then charging speed is improved, but morphology changes and dendrite formation increase reducing reliability
Solution Approach 1:
The patent uses periodic action by implementing alternating charging and discharging cycles with controlled asymmetry. During charging, lithium ions are deposited at high rate, followed by a discharging phase that removes ions at a different rate. This periodic alternation prevents continuous high-rate deposition that would cause morphology changes, while still achieving rapid charging overall.
Solution Approach 2:
The patent applies preliminary anti-action by introducing a discharging phase that counteracts the morphology changes initiated during the charging phase. The discharging process removes lithium ions in a controlled manner that reverses surface roughening and prevents dendrite formation, thereby compensating for the harmful effects of rapid charging.
3Quantity of substance
If high surface area structures form during charging, then charging capacity is improved, but internal short circuit risk increases reducing reliability
Solution Approach 1:
The patent implements periodic action by alternating charging and discharging phases. During charging, lithium ions are deposited to achieve high capacity, while the subsequent discharging phase removes ions and reduces surface area structures. This periodic cycle prevents the permanent formation of high surface area structures that would lead to internal shorts, while maintaining high charging capacity.
Solution Approach 2:
The patent applies parameter changes by adjusting discharge current parameters to optimize the removal of lithium ions from high surface area structures. By controlling discharge rate and duration, the system reduces dendritic and mossy lithium formations that create internal short circuit pathways, thereby preventing reliability issues while preserving charging capacity.
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 reduces the risk of dendrite formation and morphology changes, prolonging the life of lithium-ion battery cells by maintaining a balanced discharge rate that reverses morphology changes during charging, thereby ensuring stable operation and safety.
Implementation Method 1
When the cell is being charged, the lithium ions are deposited onto the negative electrode
Implementation Method 2
the lithium metal is oxidized during discharge
Data Source
AI summary
An electrochemical battery system, in one embodiment, includes a plurality of electrochemical cells, a memory in which command instructions are stored, and a processor configured to execute the command instructions to sequentially connect a first set of the plurality of electrochemical cells to an electrical load, disconnect the first set from the electrical load, connect a second set of the plurality of electrochemical cells to the electrical load, and disconnect the second set from the electrical load, wherein the electrochemical cells in the first set and the electrochemical cells in the second set are selected based upon a target electrochemical cell discharge rate.