Single-Crystal Cathode Battery for Low-Impedance Fast Charging
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Solution Overview
Problem
Conventional lithium-ion batteries with single crystal positive electrode materials suffer from low capacity per gram and poor C-rate performance due to high charge transfer impedance and lithium ion diffusion resistance.
Innovation Solution
A battery design featuring a positive electrode material with a polymeric single crystal morphology, characterized by a specific particle size distribution and surface area, which reduces charge transfer impedance and lithium ion diffusion resistance, thereby enhancing ionic conductivity and C-rate performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If single crystal material is used as positive electrode material, then cycling performance and high-voltage resistant performance are improved, but capacity per gram and C-rate performance deteriorate
Solution Approach 1:
The patent uses a composite material system consisting of lithium nickel cobalt manganese oxide (NCM) with specific atomic ratios (Ni:Co:Mn = 3:1:6 to 4:1:5) combined with surface modification layers. This composite approach maintains the structural stability of single crystal for good cycling performance while the optimized composition and surface treatment enhance capacity per gram and C-rate performance by improving lithium ion diffusion pathways.
Solution Approach 2:
The patent optimizes key parameters including the atomic ratios of Ni, Co, and Mn elements in the NCM compound, particle size distribution (D50 between 3-7 μm), and surface area (0.015-0.025 m²/g). By precisely controlling these parameters, the material achieves both good cycling performance and improved capacity per gram with better C-rate characteristics.
2Reliability
If single crystal material is used as positive electrode material, then high-voltage resistant performance is improved, but C-rate performance deteriorates
Solution Approach 1:
The patent applies local quality optimization through surface modification of the NCM particles. The surface region is treated differently from the bulk material, with controlled surface area (0.015-0.025 m²/g) and specific surface treatments that enhance lithium ion diffusion kinetics. This local optimization improves C-rate performance while the bulk single crystal structure maintains high-voltage resistant performance.
Solution Approach 2:
The patent segments the particle size into specific ranges (D50 between 3-7 μm with controlled distribution) to optimize both high-voltage resistance and C-rate performance. The segmented particle structure provides sufficient surface area for fast kinetics while maintaining structural integrity for voltage stability.
3Speed
If charge transfer impedance and lithium ion diffusion resistance are reduced, then C-rate performance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent reduces charge transfer impedance and lithium ion diffusion resistance by optimizing material parameters (atomic ratios, particle size D50 of 3-7 μm, surface area 0.015-0.025 m²/g) rather than through complex processing steps. This approach achieves low impedance (Rct ≤ 10 mΩ) and good C-rate performance while avoiding excessive manufacturing complexity by using controllable synthesis parameters.
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 battery exhibits improved capacity and C-rate performance, with reduced charge transfer and lithium ion diffusion impedances, leading to better lithium ion conductivity and stability during charging and discharging.
Implementation Method 1
a positive electrode plate, and the positive electrode plate includes a positive electrode material
Implementation Method 2
lithium ion diffusion resistance
Data Source
AI summary
Disclosed is a battery, and in an electrochemical impedance spectroscopy (EIS) test of the battery, a charge transfer impedance Rct of the second semicircle in an intermediate frequency region meets: Rct<15 mΩ; and a slope k of a ray in a low frequency region meets: 1.03<k<57.29. The battery has low charge transfer impedance and lithium ion diffusion resistance during charging and discharging. The battery also has good lithium ion conductivity performance on the premise of having good cycling performance, and is a battery having good cycling performance and improved capacity, as well as good C-rate performance.