Li-Ion Anode Reserve Material Prevents Lithium Plating
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Solution Overview
Problem
Conventional lithium-ion batteries face issues with lithium plating at the anode during charging, especially at low temperatures and high charge rates, leading to internal short circuits and capacity loss due to the low discharge voltage of graphite, which results in insufficient lithium accommodation and increased impedance.
Innovation Solution
Incorporating a reserve material with a reaction potential between 0 and 0.1 volts, such as SrO, Mn4N, K2SO4, CaCl2, CaF2, SrF2, Ag, Mg, or Zn, into the anode to intercalate with lithium and inhibit plating, either by mixing it with the primary active material and binder or forming a layer between the anode and separator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If graphite is used as the primary active material in the anode, then the battery achieves high energy and power density, but lithium plating occurs at low temperatures and high charge rates leading to internal short circuits and capacity loss
Solution Approach 1:
A reserve material layer is introduced as an intermediary between the graphite anode and separator. This layer has a reaction potential between lithium (0V) and graphite (0.1V), acting as a mediator that preferentially intercalates lithium ions when graphite becomes fully charged, preventing lithium plating on the graphite surface while maintaining the high power density benefits of graphite
Solution Approach 2:
The reserve material is pre-positioned on the anode surface before charging occurs. When lithium ions arrive at the anode during charging, the reserve material is already in place to intercept and intercalate excess lithium ions that would otherwise plate on the graphite, providing preliminary protection against plating before it can occur
2Quantity of substance
If the anode capacity is designed to exceed available lithium from the cathode, then all lithium can be fully accommodated in graphite, but the potential drops below 0.1V during charging leading to lithium plating
Solution Approach 1:
The invention changes the potential parameter profile during charging by introducing the reserve material layer. When graphite reaches full intercalation at 0.1V, the reserve material layer provides an additional potential stage between 0-0.1V, extending the charging voltage window and allowing continued lithium intercalation without dropping to potentials that cause plating
Solution Approach 2:
The anode is designed as a composite structure combining graphite (primary active material) with a reserve material layer having different electrochemical properties. This composite approach allows the system to utilize both materials' capabilities: graphite for high capacity and the reserve material for potential buffering to prevent plating
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 reserve material effectively prevents lithium plating by intercalating with lithium when the primary active material is fully charged, reducing the risk of internal shorts and capacity loss, thereby enhancing the battery's performance and longevity.
Implementation Method 1
The reserve material is configured to intercalate with lithium at the reaction potential responsive to the primary active material being fully intercalated to inhibit lithium plating on the anode
Data Source
AI summary
A Li-ion battery includes a cathode; an anode having a primary active material, conductive carbon, binder, and reserve material; and a separator between the cathode and anode. The reserve material has a reaction potential between a lithium reaction potential and a primary active material reaction potential. The reserve material is configured to intercalate with lithium at the reaction potential responsive to the primary active material being fully intercalated to inhibit lithium plating on the anode.