Sulfur Composite Battery Voltage Cycling
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Solution Overview
Problem
Sulfur composite cathode electrodes in lithium ion batteries experience volume changes during cycling, leading to instability, detachment from conducting agents, and reduced capacity retention and coulombic efficiency.
Innovation Solution
Cycling sulfur composite lithium ion batteries within a specific voltage range between the charge cutoff voltage and discharge cutoff voltage, using a sulfur-based polymer like sulfur grafted poly(pyridinopyridine) (SPPY) as the electrode active material, which suppresses volume change by maintaining a stable structure during charging and discharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If sulfur composite cathode electrodes are used in lithium ion batteries, then large specific capacity and low cost are achieved, but volume change during cycling causes instability and detachment from conducting agents
Solution Approach 1:
The patent uses sulfur composite materials as cathode active materials, combining sulfur with conducting agents and binders to create a composite structure that maintains electrical conductivity while accommodating volume changes during lithium ion insertion and extraction
Solution Approach 2:
The patent employs a binder system that forms a flexible matrix holding the sulfur composite particles, allowing the electrode structure to expand and contract during cycling without breaking electrical contact or detaching from the current collector
2Ease of manufacture
If sulfur composites are used as cathode active materials, then abundant resources and low cost are achieved, but capacity retention decreases with cycling times
Solution Approach 1:
The patent optimizes parameters including voltage cutoff limits, charging/discharging rates, and electrode composition ratios to minimize mechanical stress and chemical degradation during cycling, thereby extending battery life and maintaining capacity retention
Solution Approach 2:
The patent incorporates excess binder and conducting agent in the electrode formulation to create a cushioning matrix that protects sulfur particles from mechanical degradation and maintains electrical pathways throughout the battery's operational life
3Use of energy by moving object
If sulfur composite electrodes undergo volume change during cycling, then lithium ion insertion and extraction are enabled, but detachment from conducting agents occurs
Solution Approach 1:
The patent merges sulfur particles with conducting agents and binder in a unified composite structure where the binder forms a continuous matrix that holds all components together, ensuring electrical connectivity is maintained even as sulfur particles move during lithium ion cycling
Data Source
AI summary
A method for cycling a sulfur composite lithium ion battery includes a step of charging and discharging the sulfur composite lithium ion battery at a first voltage range between a predetermined highest voltage and a predetermined lowest voltage. The lithium ion battery includes an electrode active material. The electrode active material includes a sulfur composite. The step of charging and discharging satisfies at least one conditions of (1) and (2): (1) the predetermined lowest voltage of the first voltage range is larger than a discharge cutoff voltage of the sulfur composite; and (2) the predetermined highest voltage of the first voltage range is smaller than a charge cutoff voltage of the sulfur composite. A method for using a sulfur composite as an electrode active material of a lithium ion battery is also disclosed.