Lithium Secondary Battery Electrodes for High Capacity and Thermal Stability
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Solution Overview
Problem
Existing lithium secondary batteries face challenges in increasing energy density and improving high output performance due to limitations in cathode and anode materials, particularly with nickel-rich cathode active materials and non-carbon-based anode materials, which suffer from thermal instability, gas generation, and irreversible capacity loss.
Innovation Solution
A specific combination of cathode and anode active materials is employed, where the cathode includes lithium composite transition metal compounds with controlled particle diameters and compositions, and the anode uses a silicon carbon composite with optimized particle sizes, to enhance energy density and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel content in cathode active material is increased to increase capacity, then energy density is improved, but thermal stability deteriorates and gas generation increases
Solution Approach 1:
The patent uses a nickel-cobalt-manganese (NCM) composite material for the cathode active material, where nickel provides high capacity, cobalt maintains structural stability, and manganese suppresses thermal runaway. This composite approach allows the battery to achieve high energy density while maintaining thermal stability and reducing gas generation compared to pure nickel-based materials.
2Quantity of substance
If non-carbon-based anode materials (silicon, tin, oxides) are used to increase capacity, then energy density is improved, but irreversible capacity loss increases due to low initial efficiency
Solution Approach 1:
The patent optimizes the particle size parameters of the anode active material, controlling the D10, D50, and D90 values to specific ranges. This parameter optimization increases the initial efficiency of lithium insertion/extraction, thereby reducing irreversible capacity loss while maintaining high capacity. The controlled particle size distribution ensures better electrolyte penetration and more uniform current distribution.
3Reliability
If graphite is used as anode active material, then initial efficiency is maintained, but capacity per unit mass is limited to 372 mAh/g
Solution Approach 1:
The patent employs a composite anode structure combining graphite with silicon, tin, or their oxides. The graphite component maintains good initial efficiency and structural stability, while the silicon/tin oxide components provide additional lithium storage capacity beyond the 372 mAh/g limit of pure graphite. This composite approach achieves both high capacity and acceptable initial efficiency.
4Power
If lithium composite transition metal compound with controlled particle diameter is used, then diffusion resistance is reduced and high output performance is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise particle diameter ranges for the lithium composite transition metal compound (D10: 0.5-2.0 μm, D50: 2.0-5.0 μm, D90: 5.0-10.0 μm). By controlling these particle size parameters, the patent reduces lithium ion diffusion resistance and improves high-rate discharge performance. The defined ranges balance the need for small particles (low diffusion resistance) with manufacturing feasibility.
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 optimized material combination increases energy density, improves high output performance, and enhances battery cycle life by reducing side reactions and diffusion resistance, thereby improving overall battery efficiency.
Implementation Method 1
The lithium secondary battery generates electric energy by oxidation and reduction reactions during intercalation and deintercalation of lithium ions at a cathode and an anode
Implementation Method 2
an organic electrolytic solution or polymer electrolytic solution is filled between the cathode and the anode
Data Source
AI summary
A lithium secondary battery includes a cathode having a cathode active material, an anode having an anode active material, a separator, and an electrolyte. The cathode active material comprises a lithium composite transition metal compound having Ni, Co, and Mn, and has single particles and/or pseudo-single particles. Each single particle consists of one nodule, and each pseudo-single crystal is a composite of 30 or fewer nodules. The single particles and/or pseudo-single particles have an average particle diameter (D50) of 1 μm or more.