Graded Core-Shell Anode Material for High-Voltage Stability
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Solution Overview
Problem
Lithium-ion batteries face limitations in energy density, power density, cycling life, and safety due to the performance bottlenecks of commercial lithium cobalt oxide anode materials, particularly at high voltages which can cause irreversible damage and side reactions.
Innovation Solution
An anode material comprising particles with an outer dense layer and inner core, enriched with metallic and nonmetallic elements such as Al, Mg, Ti, Zr, Mn, Ni, F, B, and P, where concentrations progressively decrease from the outer layer to the core, enhancing structural stability and electrochemical performance through surface modification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high voltage (>4.5V) is applied to utilize theoretical capacity of lithium cobalt oxide anode material, then capacity is improved, but structural stability and cycling life deteriorate due to irreversible damage and side reactions
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the surface layer has different composition and properties than the bulk. The surface is enriched with Al and F elements to form a protective layer that specifically addresses the surface-related degradation issues at high voltage, while the bulk material maintains its high capacity characteristics.
Solution Approach 2:
The patent uses composite materials by combining lithium cobalt oxide with Al doping and F coating to create a composite anode material. This composite structure integrates the high capacity of LiCoO3 with the structural stability and surface protection provided by Al-F composite layers, resolving the contradiction between capacity and cycling life.
2Use of energy by moving object
If high voltage (>4.5V) is applied to utilize theoretical capacity, then energy density is improved, but structural stability deteriorates due to irreversible damage
Solution Approach 1:
The surface layer is specifically engineered with Al and F enrichment to provide local structural stability at the surface where voltage-induced stress is most severe, while the bulk material maintains its energy-dense composition for high capacity.
Solution Approach 2:
The Al doping and F coating are applied in advance during the sintering process to pre-establish a protective surface layer before the material is subjected to high voltage operation, preventing structural degradation before it occurs.
3Quantity of substance
If high voltage (>4.5V) is applied, then capacity is improved, but thermal stability deteriorates due to side reactions
Solution Approach 1:
The surface layer with Al and F enrichment creates a local barrier that specifically addresses thermal stability issues at the surface, where side reactions are most likely to occur, while the bulk material maintains its high capacity properties.
Solution Approach 2:
The patent converts the potentially harmful high voltage condition into a benefit by using the high voltage sintering process to create the beneficial Al-F surface layer, which then protects against harmful side reactions during normal operation.
4Reliability
If surface enrichment with M and A elements is increased to improve structural stability, then manufacturing complexity increases due to multi-step sintering process
Solution Approach 1:
The patent merges the doping and coating processes into a single integrated sintering operation. The Al doping and F coating are simultaneously achieved during the sintering process, eliminating the need for separate doping and coating steps and reducing manufacturing complexity.
Solution Approach 2:
The sintering process serves multiple functions simultaneously: it densifies the bulk material, dopes Al into the lattice, and coats the surface with F-containing compounds, making the process universal and reducing the number of separate manufacturing steps.
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 anode material achieves a capacity retention ratio greater than 80% after 50 cycles under 4.6V, with improved specific capacity and structural stability, overcoming the shortcomings of existing lithium cobaltate anode materials.
Implementation Method 1
The outer dense layer is evenly enriched with an M element and an A element. The inner layer comprises the M element and the A element, concentrations of the M element and the A element progressively decreasing in the inner layer along a direction from the outer dense layer to the particle core.
Implementation Method 2
forming primary sintered particles by sintering the primary mixture with a first sintering process and a second sintering process, the first sintering process comprising heating the primary mixture to a first temperature ranging from 700 degrees Celsius to 900 degrees Celsius, and sintering the primary mixture at the first temperature for a first time period H1
Data Source
AI summary
An anode material used for a lithium-ion battery utilizing a greater part of the storage capacity includes particles in outer dense layer, then inner layer, and then particle core. The outer dense layer is evenly enriched with an M element and an A element, the enrichment decreasing from the outside towards the core. The particle core does include the M element and the A element at a concentration greater than zero and having an average distribution. The M element includes Al, or Al and at least one of Mg, Ti, Zr, Mn. The A element includes F, or F and at least one of B, P, and N. A method for manufacturing the anode material and a lithium-ion battery are also disclosed.