Pre-lithiated Anode Phased Lithium Introduction for Capacity Retention
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Solution Overview
Problem
Lithium ion cells experience significant lithium loss during formation cycles and elevated temperature aging, leading to reduced specific capacity and capacity retention, which affects cell performance and cost.
Innovation Solution
The process involves pre-lithiating anodes and controlling lithium transfer between the anode and cathode through phased introduction and heat treatment to maximize cycling capability and retention, using commercially available pre-lithiated anodes or lithium-bearing additives, and optimizing the pre-lithiation amount to offset initial and aging losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium is added to the cell prior to assembly to replace first cycle losses, then specific capacity is improved, but the risk of forming lithium metal or dendrites on the anode increases
Solution Approach 1:
The anode is pre-lithiated before cell assembly by exposing it to lithium-bearing additives in a controlled environment, thereby pre-compensating for first cycle lithium losses. This preliminary action ensures that the anode has sufficient lithium reservoir from the start, improving specific capacity while the controlled process prevents excessive lithium accumulation that could lead to dendrite formation.
Solution Approach 2:
The patent optimizes the amount of pre-lithiation by controlling the dosage of lithium-bearing additives and the exposure conditions. By carefully adjusting these parameters, the anode achieves the right balance between having enough lithium to compensate for losses and avoiding excess lithium that could form dendrites during cycling.
2Duration of action of stationary object
If the anode capacity is increased to maximize cycling capability, then capacity retention is improved, but the likelihood of lithium plating and dendrite formation increases
Solution Approach 1:
The patent applies partial pre-lithiation rather than full lithiation of the anode. By adding a controlled, sub-stoichiometric amount of lithium-bearing additives, the anode capacity is partially increased to compensate for cycling losses without reaching the threshold that would cause lithium plating and dendrite formation during subsequent cycling.
3Quantity of substance
If lithium loss during formation cycles is reduced, then specific capacity is improved, but the formation process complexity increases
Solution Approach 1:
Instead of attempting to control and minimize lithium loss during the formation cycles through complex process parameters, the patent takes a preliminary action by pre-lithiating the anode before assembly. This shifts the strategy from managing formation losses to pre-compensating for them, thereby reducing formation process complexity while maintaining high specific capacity.
4Duration of action of stationary object
If pre-lithiation amount is increased to offset aging losses, then capacity retention is improved, but the risk of exceeding maximum anode capacity increases
Solution Approach 1:
The patent optimizes the pre-lithiation parameters by carefully controlling the amount of lithium-bearing additives and the exposure conditions. This ensures that the anode receives just enough lithium to offset aging losses during storage and initial cycling without exceeding the maximum anode capacity, thereby maintaining capacity retention while avoiding safety constraints.
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
This approach enhances specific and volumetric capacity retention by minimizing lithium loss and electrolyte consumption, thereby extending cell lifetime and reducing costs.
Implementation Method 1
Heat and or partial formation cycling are used to accelerate and control lithium losses occurring in the early operation of a lithium-ion battery
Implementation Method 2
pre-lithiating an anode
Implementation Method 3
controlling lithium transfer between the anode and cathode
Implementation Method 4
assembling the anode, a cathode, a separator and electrolyte into a sealed cell
Data Source
AI summary
The present invention relates to a method for combining anode pre-lithiation, limited-voltage formation cycles, and accelerating aging via heated storage to maximize specific capacity, volumetric capacity density and capacity retention of a lithium-ion electrochemical cell.