Lithium Cell Cathode Structure for High Energy Density
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Solution Overview
Problem
Conventional lithium-sulfur batteries have low cycle resistance due to structural changes during discharge, leading to significant loss of storage capacity and energy release, and are costly to produce, while lithium-ion batteries are heavy and inefficient for high-energy applications like electric vehicles.
Innovation Solution
A lithium cell with a cathode structure featuring a base material that conducts electrons and Li ions, including crosspieces and carrier structures for optimal surface area and active material distribution, combined with a solid electrolyte and anode structure for enhanced stability and efficiency, allowing for high energy and power density with improved cycle resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium-sulfur batteries are used to achieve high energy density, then energy density increases, but cycle resistance decreases due to structural changes during discharge
Solution Approach 1:
The cathode structure is segmented into a base material layer with a specific three-dimensional structure that divides and supports the sulfur active material. This segmentation prevents uncontrolled structural changes during discharge by providing a stable framework that maintains integrity while accommodating volume changes of sulfur.
Solution Approach 2:
The base material is designed with specific local properties including porosity, conductivity, and mechanical strength distributed throughout the structure. These local quality features enable the cathode to simultaneously achieve high energy density through sulfur loading while maintaining cycle resistance through the stabilizing base material network.
2Ease of manufacture
If conventional production methods are used, then production simplicity is maintained, but manufacturing cost increases and performance stability decreases
Solution Approach 1:
The invention specifies particular parameter ranges for the base material including porosity (30-70%), conductivity thresholds, and thickness ratios that enable conventional production methods to achieve consistent high-performance results. By defining these parameters, the invention transforms qualitative performance goals into quantifiable manufacturing specifications.
3Reliability
If graphite intercalation anode is used to prevent lithium metal corrosion, then anode stability improves, but cell voltage decreases
Solution Approach 1:
The base material structure acts as an intermediary between the sulfur cathode and lithium metal anode, enabling the use of lithium metal while preventing direct harmful interactions. The base material's conductivity and structural properties mediate the interface, allowing high voltage operation with lithium metal anode stability.
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 lithium cell achieves high energy densities of approximately 600 Wh/kg, improved cycle resistance, and cost-effective production using simple processes, enabling efficient and stable operation for electric vehicles.
Implementation Method 1
a cathode structure made of a base material that conducts both electrons and Li ions
Implementation Method 2
The electrically conductive material, in this instance, may be a metal, an alloy or another electrically conductive material, which may be freeze cast and sintered in particulate form
Implementation Method 3
which may be freeze cast and sintered in particulate form
Data Source
AI summary
A lithium cell is described having a cathode structure made of a base material which conducts electrons and Li ions. The cathode structure includes a continuous substrate, which provides a continuous base area, starting from which a plurality of crosspieces extends. The crosspieces provide crosspiece surfaces, starting from which carrier structures extend. The carrier structures provide carrier surfaces on which active material is distributed. In addition, an accumulator is also described in which a plurality of lithium cells is stacked. A method for producing a lithium cell is also described.