Doped Graphene Nanosheet Anodes for Lithium Battery Capacity
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Solution Overview
Problem
Secondary lithium batteries face challenges in long-term cycling stability and performance degradation of anodes, particularly with graphene-based materials, which require improvements in capacity and durability for automotive applications like electric vehicles.
Innovation Solution
The use of nitrogen, boron, sulfur, or phosphorus-doped graphene nanosheets (M-GNS) as anode materials, which are agglomerated into sheets, spheres, or rods, and coated with a binder on a conductive substrate, enhancing electrical conductivity and stability during charge and discharge cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If graphene nanosheets are used as anode material to increase capacity, then initial capacity is improved, but long term cycling stability deteriorates with performance degradation
Solution Approach 1:
The patent applies parameter changes by doping graphene nanosheets with heteroatoms (nitrogen, boron, sulfur, phosphorus) to modify the chemical and electronic properties of the carbon structure. This changes the electrochemical parameters of the anode material, enabling both high capacity and improved cycling stability through altered electron distribution and enhanced structural integrity during charge-discharge cycles.
Solution Approach 2:
The patent employs composite materials by creating doped graphene nanosheet structures where heteroatoms are incorporated into the graphene lattice. These composite structures combine the high surface area and conductivity of graphene with the beneficial electronic properties introduced by doping elements, achieving both high capacity and long-term stability that neither component could provide alone.
2Reliability
If traditional graphite and carbon-based anode materials are used, then cycling stability is maintained, but capacity is limited
Solution Approach 1:
The patent transforms traditional carbon-based anode materials by incorporating heteroatom doping into graphene structures. This parameter change increases the theoretical capacity beyond that of conventional graphite while maintaining the structural stability needed for long cycling life, effectively breaking the capacity-stability trade-off that limited traditional materials.
Solution Approach 2:
The patent applies local quality by introducing heteroatoms at specific positions within the graphene lattice structure. These localized doping sites create regions of enhanced electronic activity and improved Li+ insertion/extraction kinetics, allowing high capacity performance in specific areas while the overall graphene structure maintains its structural integrity and cycling stability.
3Quantity of substance
If Si-based and Sn-based anode materials are used to increase capacity, then capacity is improved, but cycle life deteriorates with performance degradation
Solution Approach 1:
The patent uses composite materials by doping graphene with heteroatoms to create a stable carbon-based composite anode. This composite structure provides the high capacity characteristics of Si and Sn-based materials while avoiding their fundamental drawback of structural degradation during cycling, as the doped graphene maintains structural integrity through its robust sp2-bonded lattice.
Solution Approach 2:
The patent replaces the disposable, degradation-prone Si and Sn-based materials with a more durable doped graphene composite that provides similar or superior capacity but with extended service life. The heteroatom-doped graphene structure resists the performance degradation that plagues traditional high-capacity materials, effectively creating a long-lasting alternative.
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 doped graphene nanosheets significantly increase the capacity and stability of lithium batteries, reducing performance degradation over cycles, with nitrogen-doped graphene nanosheets showing improved reversible charge/discharge capacity and structural integrity compared to undoped graphene.
Implementation Method 1
Doping of heteroatom into carbon structures can tailor both chemical and electronic nature. Nitrogen doping was reported to enhance Li+ intercalation/de-intercalation in carbon nanotubes and increase electrochemical capacity of nitrogen-containing polymeric carbon.
Implementation Method 2
Nitrogen doping was reported to enhance Li+ intercalation/de-intercalation in carbon nanotubes
Implementation Method 3
Graphene has various remarkable properties, for example, an ultra-high surface area (2630 m2g−1), high electrical conductivity (resistivity: 10−6 Ωcm) and high chemical stability
Data Source
AI summary
A secondary lithium battery having an anode comprising graphene nanosheets doped with a doping element selected from the group consisting of nitrogen, boron, sulfur, phosphorous and combinations thereof. The secondary lithium battery and the anode provide capacity and other performance without degradation during long term charge and discharge cycling.