Composite Negative Active Material for Fast-Charging Battery Anodes
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Solution Overview
Problem
Current secondary batteries face limitations in capacity, energy density, charge/discharge rate, and cycling stability due to the use of graphite negative electrodes, which exhibit low theoretical specific capacity and swelling issues under fast charging, while hard carbon materials show potential but are hindered by potential hysteresis and irreversible capacity.
Innovation Solution
A negative active material comprising composite particles with a disordered carbon structure and an ordered carbon or metal oxide structure, enhancing compacted density, ion diffusion, and reducing internal polarization, thereby improving energy density, rate performance, and cycling stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If graphite materials are used as negative electrode material, then high conductivity and high stability are achieved, but low theoretical specific capacity limits energy density
Solution Approach 1:
The patent uses composite carbon materials combining ordered graphite structures with disordered carbon phases (amorphous carbon, hard carbon, soft carbon) to create a negative electrode that achieves both high stability from the ordered regions and higher specific capacity from the disordered regions, resolving the contradiction between stability and capacity
2Speed
If graphite negative electrodes are used for fast charging, then high conductivity is maintained, but serious swelling occurs resulting in decreased service life
Solution Approach 1:
The patent applies local quality by creating regions with different carbon structures within the negative electrode particles - ordered graphite regions provide structural stability while disordered carbon regions accommodate volume changes during fast charging, preventing swelling and maintaining service life
Solution Approach 2:
The disordered carbon regions in the composite structure provide porous pathways that facilitate rapid ion transport during fast charging while accommodating volume expansion, thereby maintaining both high charge rate and service life
3Quantity of substance
If hard carbon materials are used to increase specific capacity, then reversible specific capacity increases to 500-1000 mAh/g, but potential hysteresis and large irreversible capacity affect commercialization
Solution Approach 1:
The patent combines hard carbon or soft carbon with ordered graphite structures to create a composite that maintains the high specific capacity benefits of disordered carbon while the ordered regions reduce potential hysteresis and irreversible capacity losses, making the material commercially viable
4Quantity of substance
If disordered carbon structure is used, then reversible specific capacity increases, but compacted density decreases due to low true density
Solution Approach 1:
The composite structure combines low-density disordered carbon regions (providing high capacity) with high-density ordered graphite regions (providing high compacted density), achieving both high specific capacity and high energy density by volume
5Volume of stationary object
If second region with ordered structure is added to composite particle, then compacted density increases, but device complexity increases
Solution Approach 1:
The patent merges multiple carbon phases (ordered and disordered) into a single composite particle structure that can be processed as one material, avoiding the complexity of assembling separate components while achieving high compacted density through the internal structure of the composite particles
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 particle structure maintains capacity levels while increasing energy density and improving fast charging, rate, and cycling performance of secondary batteries by reducing ion diffusion paths and internal polarization.
Implementation Method 1
increasing a gram capacity of the negative active material and a diffusion coefficient of active ions inside the negative active material
Implementation Method 2
the second region including the ordered structure can further effectively reduce a free path for the active ions, improve internal diffusion kinetics of the negative active material, and reduce internal polarization
Data Source
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AI summary
This application provides a negative active material, a secondary battery, and an electronic apparatus. The negative active material of this application includes composite particles. The composite particle includes a first region and a second region, where the first region includes a disordered carbon structure, and the second region includes an ordered carbon structure and/or a metal oxide structure. The negative active material of this application has a high gram capacity and active ion diffusion coefficient, so that a secondary battery containing such negative active material has a high energy density and excellent cycling performance, rate performance, and fast charging capacity.