Composite Negative Electrode for Fast-Charging Lithium-Ion Batteries
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Solution Overview
Problem
Current lithium-ion batteries with high energy density suffer from inferior charging capabilities and rapid cycle capacity fading, especially during fast charging, due to issues with silicon- or tin-based negative electrode materials, which experience particle breakage and rapid SEI film repair, leading to short lifespan.
Innovation Solution
A secondary battery design incorporating a negative electrode plate with a composite active material layer comprising graphite, amorphous carbon (hard, soft, or porous), and a non-carbon material like silicon or tin, optimized in mass ratios and particle sizes to enhance charging performance, cycle stability, and longevity by minimizing expansion rebound and leveraging synergistic effects among materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high energy density is achieved using silicon- or tin-based negative electrode materials, then energy density is improved, but charging capability deteriorates and cycle capacity fading occurs during fast charging
Solution Approach 1:
The patent applies composite materials by combining silicon- or tin-based negative electrode materials with graphite and amorphous carbon materials. This composite structure allows the high-capacity silicon/tin materials to provide high energy density while the graphite and amorphous carbon components buffer expansion stresses and maintain structural integrity during fast charging, thereby resolving the contradiction between energy density and charging capability/cycle stability
Solution Approach 2:
The patent changes the physical and chemical parameters of the negative electrode material system by controlling particle size distribution, mass ratios of different materials, and surface properties. These parameter optimizations enable the composite material to achieve both high energy density and good fast-charge performance by balancing lithium insertion/extraction kinetics and mechanical stability
2Speed
If fast charging is performed on batteries with silicon- or tin-based negative electrode materials, then charging speed is improved, but particle breakage occurs leading to rapid SEI film repair and shortened lifespan
Solution Approach 1:
The patent applies beforehand cushioning by incorporating graphite and amorphous carbon materials that act as buffer components before fast charging occurs. These materials preemptively absorb and distribute the expansion rebound stresses that would otherwise cause particle breakage during fast charging, preventing structural damage and extending battery service life while maintaining high charging speeds
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 achieves improved fast-charge performance, extended cycle life, and higher energy density by balancing material advantages and minimizing disadvantages, resulting in a more durable and efficient energy storage system.
Implementation Method 1
lithium is preferentially inserted into the amorphous carbon
Implementation Method 2
the three constituents coordinate with each other synergistically to not only effectively improve the charging capabilities and cycle performance
Implementation Method 3
the expansion rebound rate of the amorphous carbon is low. Therefore, the amorphous carbon is used in a high-energy-density system containing a non-carbon negative electrode
Data Source
AI summary
A secondary battery is disclosed, including: a positive electrode plate, a negative electrode plate, and a separator. The separator is disposed between the positive electrode plate and the negative electrode plate. The negative electrode plate includes a negative current collector and a negative active material layer disposed on at least one surface of the negative current collector. A negative active material in the negative active material layer includes graphite, amorphous carbon, and a non-carbon negative electrode material. The amorphous carbon includes one or more of hard carbon, soft carbon, or porous carbon. The non-carbon negative electrode material is a silicon-based negative electrode material and/or a tin-based negative electrode material.