Graphite Anode Composite With Carbon Black for Battery Durability
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Solution Overview
Problem
Existing nonaqueous electrolyte secondary batteries using graphite particles as negative electrode active material face durability issues due to peeling of scaly graphite during charge and discharge cycles, leading to decreased conductivity and capacity retention.
Innovation Solution
A negative electrode active material comprising graphite particles with carbon black present in internal voids and on the surface, forming a carbon coating, maintains conductive paths and reduces peeling, using a mechanochemical process to distribute carbon black uniformly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If graphite particles are used as negative electrode active material, then energy density is improved, but durability deteriorates due to peeling during charge-discharge cycles
Solution Approach 1:
The patent combines graphite particles with carbon black to form a composite negative electrode active material. The carbon black fills internal voids and forms a conductive coating on the surface, creating a composite structure that maintains the high energy density of graphite while adding durability through the conductive carbon network that prevents peeling damage.
2Reliability
If carbon black is added to maintain conductive paths, then durability is improved, but device complexity increases
Solution Approach 1:
The patent merges the functions of the negative electrode active material and conductive additive into a single composite material system. Carbon black serves dual purposes: filling internal voids of graphite particles and forming a conductive coating on the surface, thereby maintaining conductivity without requiring separate conductive network structures.
3Reliability
If carbon black is distributed in internal voids and on surface, then conductivity is maintained, but manufacturing precision requirements increase
Solution Approach 1:
The patent utilizes the porous internal structure of graphite particles to accommodate carbon black. The internal voids of the graphite particles serve as reservoirs for carbon black, allowing it to be distributed throughout the particle interior and on the surface, maintaining conductivity even when some graphite scales peel off during cycling.
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 solution effectively curtails durability losses by maintaining conductivity and capacity retention, enhancing the battery's performance and lifespan.
Implementation Method 1
using a mechanochemical process to distribute carbon black uniformly
Implementation Method 2
carbon black or a carbon coating portion formed by carbon black is present not only on the surface of graphite particles but also in internal voids. As a result, this allows maintaining good conductive paths in the negative electrode active material
Data Source
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AI summary
Provided is a technique that allows curtailing decreases in the durability of a nonaqueous electrolyte secondary battery. A negative electrode active material disclosed here is a particulate negative electrode active material (10) used in a nonaqueous electrolyte secondary battery (100). The negative electrode active material (10) contains graphite particles (11) which are aggregates of scaly graphite (11a), and carbon black (12). The carbon black (12) is present in internal voids (11s) of the graphite particles (11), and part of the carbon black (12) accumulates on the surface of the graphite particles (11) thereby forming a carbon coating portion (13).