Phosphorus-Bonded Graphite Anode Coating for High-Temperature Cycle Life
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current lithium secondary batteries face instability and reduced life characteristics at high temperatures due to side reactions between spheronized natural graphite and the electrolyte, particularly at edge sites, leading to insufficient performance for applications like electric vehicles.
Innovation Solution
The anode active material involves spheronized natural graphite particles with phosphorus atoms bonded to edge planes and a selective amorphous or low-crystallinity carbon coating on both edge and basal planes, enhancing surface stability and reducing reactivity with the electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If spheronized natural graphite is used as anode active material, then lithium storage capacity is improved, but stability and life characteristics at high temperatures deteriorate due to side reactions with electrolyte
Solution Approach 1:
The patent applies local quality by selectively coating only the edge planes of graphite particles with amorphous carbon, while leaving basal planes uncoated. This targeted approach stabilizes the reactive edge sites that cause electrolyte decomposition at high temperatures, while preserving the lithium storage capacity of the basal planes. The selective local modification resolves the contradiction between high capacity and high-temperature stability.
Solution Approach 2:
The amorphous carbon coating acts as an intermediary layer between the graphite edge planes and the electrolyte. This intermediate carbon layer prevents direct contact and side reactions between the electrolyte and reactive graphite edge sites, thereby improving high-temperature stability while allowing lithium ion diffusion through the coating, maintaining capacity.
2Ease of manufacture
If flaky natural graphite fragment particles are agglomerated into spheronized particles, then manufacturing ease is improved, but structural stability deteriorates due to mechanical cracks during charge/discharge cycles
Solution Approach 1:
The patent applies local quality by selectively coating only the edge planes of graphite particles with amorphous carbon, while leaving basal planes uncoated. This targeted approach stabilizes the reactive edge sites that cause electrolyte decomposition at high temperatures, while preserving the lithium storage capacity of the basal planes. The selective local modification resolves the contradiction between high capacity and high-temperature stability.
Solution Approach 2:
The amorphous carbon coating is applied beforehand to the edge planes of graphite particles, creating a protective cushioning layer that prevents mechanical cracks during charge/discharge cycles. This pre-applied protective layer absorbs stress and prevents structural degradation, maintaining stability while allowing the particles to be easily manufactured as spheronized forms.
3Speed
If edge planes of graphite particles are exposed, then lithium ion diffusion is improved, but harmful factors increase due to electrolyte decomposition reactions
Solution Approach 1:
The patent applies local quality by selectively coating only the edge planes of graphite particles with amorphous carbon, while leaving basal planes uncoated. This targeted approach stabilizes the reactive edge sites that cause electrolyte decomposition at high temperatures, while preserving the lithium storage capacity of the basal planes. The selective local modification resolves the contradiction between high capacity and high-temperature stability.
Solution Approach 2:
The amorphous carbon coating acts as an intermediary layer between the graphite edge planes and the electrolyte. This intermediate carbon layer prevents direct contact and side reactions between the electrolyte and reactive graphite edge sites, thereby improving high-temperature stability while allowing lithium ion diffusion through the coating, maintaining capacity.
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
This solution improves the stability and cycle life of lithium secondary batteries at both high and room temperatures by preventing electrolyte decomposition and enhancing lithium ion diffusion and electrical conductivity.
Implementation Method 1
phosphorus (P) atoms are bonded to edge planes of all or some of the flaky natural graphite fragment particles
Implementation Method 2
an amorphous or low-crystallinity carbon coating layer is formed on the edge planes and basal planes of all or some of the flaky natural graphite fragment particles
Implementation Method 3
enhancing lithium ion diffusion and electrical conductivity
Data Source
AI summary
Provided are an anode active material for a lithium secondary battery including spheronized natural graphite particles. The spheronized natural graphite particles have a structure in which flaky natural graphite fragment particles are agglomerated and granulated into a cabbage shape or random shape, phosphorus (P) atoms are bonded to edge planes of all or some of the flaky natural graphite fragment particles that constitute the interior or surface of the spheronized natural graphite particles, and an amorphous and/or low-crystallinity carbon coating layer is formed on the edge planes and basal planes of all or some of the flaky natural graphite fragment particles, a method of producing the same, and a lithium secondary battery including the same.