Negative Electrode Plate With Hollow Additives for Expansion Buffering
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Solution Overview
Problem
Secondary batteries face significant safety challenges due to expansion forces that can lead to electrolyte leakage, reduced cycle performance, and structural failure, particularly at the negative electrode, which existing technologies address inadequately without compromising energy density.
Innovation Solution
A negative electrode plate design incorporating an additive with a shell wall thickness of 20 nm to 300 nm and a cavity volume ratio of 40% to 90% provides a buffer for expansion, maintaining structural stability and reducing expansion forces while minimizing additive usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional negative electrode plates are used, then energy density is maintained, but expansion forces cause safety issues and structural failure
Solution Approach 1:
The patent introduces hollow spherical additives with cavities into the negative electrode active material layer before battery assembly. These hollow spheres act as pre-positioned buffer structures that can absorb expansion forces generated during lithium insertion, preventing structural damage and safety issues before they occur. The cavity structure provides ahead-of-time cushioning capacity without requiring additional space or compromising energy density.
Solution Approach 2:
The patent utilizes hollow spherical additives with internal cavities (porous structure) dispersed within the negative electrode active material layer. These porous hollow spheres provide void space that can accommodate volume changes during lithium insertion, absorbing expansion forces while maintaining overall electrode integrity. The porous structure allows the additive to function as a buffer without significantly increasing electrode volume.
2Reliability
If hollow spherical additives are added to reduce expansion forces, then safety performance improves, but energy density decreases due to additive occupation of space
Solution Approach 1:
The patent optimizes the cavity volume ratio of the hollow spherical additives to balance safety performance and energy density. By controlling the cavity volume ratio parameter within specific ranges, the additive provides sufficient buffer capacity for expansion forces while minimizing the volume occupied by non-active material. This parameter optimization allows the system to achieve both safety improvement and energy density preservation.
Solution Approach 2:
The patent distributes hollow spherical additives locally within the negative electrode active material layer, concentrating the buffer function in specific regions where expansion forces are most problematic. The additives are dispersed throughout the active material layer, providing localized cushioning where needed while leaving other regions available for active lithium storage. This local quality approach ensures safety improvement without uniformly reducing energy density across the entire electrode.
3Reliability
If the cavity volume ratio of hollow spherical additives is increased to enhance buffering capacity, then expansion force reduction improves, but structural stability decreases
Solution Approach 1:
The patent identifies and controls the cavity volume ratio parameter of hollow spherical additives to achieve optimal balance between buffering capacity and structural stability. By setting the cavity volume ratio within specific ranges, the additive provides sufficient void space for absorbing expansion forces while maintaining adequate shell wall thickness to ensure structural integrity. This parameter control prevents both over-expansion (which would compromise stability) and under-buffering (which would fail to reduce expansion forces).
Solution Approach 2:
The patent uses hollow spherical additives with cavity structures that replicate the volume expansion behavior of lithium-containing compounds during charging. The hollow spheres are designed to expand in a controlled manner that mirrors the expansion of active materials, providing a complementary buffer that absorbs excess expansion forces while maintaining structural coherence. This copying of expansion behavior allows the additive to function synergistically with the active material.
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 design effectively reduces expansion forces and enhances safety performance without significantly affecting energy density, improving cycle and rate performance of secondary batteries.
Implementation Method 1
the additive having a larger cavity structure enables it to undergo a larger elastic deformation, which in turn can effectively slow down the negative effect caused by an expansion of the negative electrode
Data Source
AI summary
The present application provides a negative electrode plate, a method of preparing the same, a secondary battery, and an electrical device. The negative electrode plate includes a negative electrode current collector and a negative electrode active material layer provided on the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material and an additive, the additive includes a shell wall and a cavity located on an inner side of the shell wall, a thickness of the shell wall is denoted as d, a volume of the cavity is denoted as Vh, a volume of the additive is denoted as Vw, and the additive satisfies 20 nm≤d≤300 nm and 40%≤Vh/Vw≤90%. The present application can effectively reduce the expansion force of secondary batteries and improve the safety performances of secondary batteries.