Halide Composite Cathode Plate for Low-Impedance Solid-State Batteries
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Solution Overview
Problem
Conventional lithium-ion batteries face safety risks due to flammable organic solvents and have challenges with interface impedance and stability between electrode materials and solid-state electrolytes, leading to poor rate performance, cycle life, and voltage decay.
Innovation Solution
A composite positive electrode plate is developed, comprising a positive electrode active material and a halide solid-state electrolyte with a chemical formula of Li2+a Zr1-a Fea Cl6-x-y Brx Iy, where 0 < a ≤ 0.5, x = 0 to 6, y = 0 to 6, and x+y ≤ 6, which improves compaction density and ionic conductivity, enhancing compatibility with high-voltage positive electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solid-state electrolytes are used, then safety is improved, but interface impedance increases and matching with positive electrode material deteriorates
Solution Approach 1:
The patent modifies the chemical composition parameters of the solid-state electrolyte by introducing dual doping elements (e.g., Al and Li, or Mg and Li) at controlled concentrations (0.01-0.10 mol each per mole of electrolyte). This parameter optimization reduces interface impedance while maintaining safety, achieving a balance between reliability and electrical performance through systematic compositional tuning.
Solution Approach 2:
The patent creates a composite electrolyte system combining the base solid-state electrolyte (e.g., Li3PO4-based) with multiple dopant elements (Al, Li, Mg, etc.) to form a multi-component composite material. This composite structure improves interfacial compatibility with positive electrode materials while maintaining the inherent safety advantages of solid-state electrolytes, effectively reducing interface impedance through synergistic material design.
2Reliability
If solid-state electrolytes are used, then safety is improved, but rate performance deteriorates
Solution Approach 1:
The patent optimizes ionic conductivity parameters through dual doping strategies, achieving electrolytes with ionic conductivity ≥10^-4 S/cm (and in some embodiments ≥10^-3 S/cm). This parameter enhancement directly improves lithium-ion transport kinetics, thereby improving rate performance while maintaining the safety advantages of solid-state electrolytes.
Solution Approach 2:
The patent introduces localized doping regions within the electrolyte structure, where dopant elements (Al, Li, Mg) are strategically positioned to create high-conductivity pathways for lithium-ion transport. This local quality enhancement at the electrolyte-electrode interface and within the electrolyte bulk improves rate performance without compromising overall safety.
3Reliability
If solid-state electrolytes are used, then safety is improved, but cycle life deteriorates
Solution Approach 1:
The patent employs pre-doping of the solid-state electrolyte with elements like Al and Li before electrode assembly, which creates a stable and conductive electrolyte phase in advance. This beforehand preparation prevents interface degradation during cycling, cushioning against capacity fade and maintaining stable electrochemical performance over extended cycles while preserving safety.
Solution Approach 2:
The doped solid-state electrolyte acts as an intermediary layer between the positive electrode material and the external environment, mediating ion transport and protecting the electrode from degradation. The dual-doped electrolyte composition (e.g., Li3-2x-yPO4 with Al and Li dopants) serves as a stable interface mediator that enhances cycle life by preventing direct contact and harmful reactions between electrode materials and electrolyte impurities.
4Reliability
If solid-state electrolytes are used, then safety is improved, but voltage decay accelerates
Solution Approach 1:
The patent optimizes the electrochemical stability window parameters of the solid-state electrolyte through dual doping, achieving electrolytes that maintain stable voltage characteristics over extended cycling. The controlled introduction of dopant elements (0.01-0.10 mol each) adjusts the electrolyte's electronic and ionic properties, reducing polarization and voltage decay while maintaining the safety benefits of solid-state operation.
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 composite positive electrode plate enhances the rate performance and cycle life of lithium-ion batteries by improving lithium-ion conduction, suppressing side reactions, and stabilizing the interface with the solid-state electrolyte, thereby reducing voltage decay and improving initial Coulombic efficiency.
Implementation Method 1
enhance the lithium-ion conduction ability of the composite positive electrode plate
Implementation Method 2
effectively suppressing side reactions between the composite positive electrode plate and the sulfide electrolyte under high voltage
Data Source
Figure 1~2
AI summary
The disclosure provides a composite positive electrode plate and a préparation method and applications thereof. The composite positive electrode plate at least includes a positive electrode active material and a halide solid-state électrolyte. A chemical formula of the halide solid-state électrolyte is Ti2+aZr1-aFeaCl6-x-yBrxIy, where 0 < a ≤ 0.5, x = 0 to 6, y = 0 to 6, x+y ≤ 6, and a compaction density of the composite positive electrode plate is 2.8 g/cm3 to 3.4 g/cm3. The composite positive electrode plate and the préparation method and applications thereof improve the compaction density of the positive electrode plate and thus enhance the rate performance and cycle life of the lithium-ion battery.