Lithium-Sulfur Battery Activation via CV Discharge and Aging
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Solution Overview
Problem
The existing activation process for lithium-sulfur batteries is lengthy and leads to significant degradation due to the 'shuttle' mechanism of lithium polysulfide, affecting battery performance and capacity.
Innovation Solution
A method involving constant voltage discharging and aging in a discharged state is employed to activate the battery, reducing the number of charge and discharge repetitions, thereby shortening the activation time and maintaining high performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If discharge is performed at a low rate (C-rate) for effective conversion during initial discharging, then conversion completeness is improved, but process time becomes too long
Solution Approach 1:
The patent applies preliminary action by performing a first discharge at a low C-rate (0.05C to 0.2C) before subsequent charge-discharge cycles. This initial low-rate discharge ensures complete conversion of sulfur to lithium sulfide, properly activating the battery. The preliminary action at optimized conditions prepares the battery for faster subsequent cycling, resolving the contradiction between conversion completeness and process time.
2Reliability
If conventional activation process is used, then battery activation is achieved, but significant degradation occurs due to shuttle mechanism
Solution Approach 1:
The patent uses preliminary action by performing the first discharge at a low C-rate before subsequent cycling. This preliminary discharge at optimized conditions ensures complete conversion and proper activation, reducing the formation of intermediate lithium polysulfides that cause the shuttle effect. By completing the activation properly in advance, subsequent degradation is minimized.
Solution Approach 2:
The patent applies parameter changes by optimizing the first discharge C-rate to a specific range (0.05C to 0.2C) and setting a termination voltage (1.0V to 2.0V). These parameter optimizations ensure complete sulfur conversion while minimizing harmful intermediate products. The modified activation parameters reduce shuttle mechanism degradation compared to conventional activation processes.
3Reliability
If multiple charge and discharge repetitions are performed for activation, then activation is achieved, but activation time is extended
Solution Approach 1:
The patent applies preliminary action by performing one optimized first discharge at low C-rate that achieves complete activation. This preliminary action at properly optimized conditions eliminates the need for multiple repetitive charge-discharge cycles, significantly reducing activation time while maintaining activation effectiveness.
Solution Approach 2:
The patent applies skipping by rushing through the activation process with a single optimized first discharge rather than performing multiple repetitive cycles. The low C-rate first discharge at optimized termination voltage completes the activation in one step, skipping unnecessary repeated cycles and reducing overall activation time.
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 significantly reduces the initial discharge time, suppresses battery degradation, and maintains long life characteristics, achieving superior capacity, Coulombic efficiency, and stability compared to conventional methods.
Implementation Method 1
During discharging, in the continuous reduction reaction, lithium polysulfide ((LiPS): Li2Sx, 8≥x≥1) phase of a linear structure is formed
Implementation Method 2
dissolution of the intermediate product and diffusion causes problems
Implementation Method 3
moves to the negative electrode due to the chemical potential and the concentration gradient between the positive electrode and the negative electrode
Implementation Method 4
Lithium polysulfide causes capacity reduction on the surface of the lithium metal negative electrode due to the shuttle effect
Implementation Method 5
dissolution of the intermediate product and diffusion causes problems
Implementation Method 6
hinders the movement of lithium ions, resulting in degradation of rate characteristics
Data Source
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AI summary
The present disclosure relates to a method for manufacturing a lithium-sulfur battery, and more particularly, to an activation method of a lithium-sulfur battery through initial discharge. The present disclosure is characterized by activation of the lithium-sulfur battery through constant voltage (CV) discharge before initial charge. The method for manufacturing the lithium-sulfur battery according to an embodiment of the present disclosure may significantly reduce the initial discharge time in the activation process of the battery.