Surface-Engineered Carbon Anode for Sodium-Ion Batteries
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Solution Overview
Problem
Current sodium-ion battery anode materials face challenges with irreversible capacity loss due to the formation of a solid electrolyte interphase (SEI) layer, which consumes alkali metal ions and limits cycle life, and lack efficient surface engineering to enhance electrochemical performance.
Innovation Solution
Development of surface-engineered carbon-containing anode materials with a core comprising primary carbon materials and an outer surface of chemically bonded carbonised materials, optimized through chemical vapour deposition to control the SEI layer's stability and reduce irreversible capacity, featuring a specific open micropore surface area and low surface oxygen content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If graphite is used as anode material in sodium-ion batteries, then high gravimetric and volumetric capacity is achieved, but electrochemical activity towards sodium is severely restricted due to large atomic radius of sodium
Solution Approach 1:
The patent applies local quality by creating distinct regions within the anode material: an inner core region with graphite crystal structure for high capacity, and an outer shell region with disordered hard carbon structure for good electrochemical activity. This spatial differentiation allows each region to perform its optimal function - the core provides quantity while the shell provides reliability.
Solution Approach 2:
The patent employs composite materials by combining graphite and hard carbon in a core-shell architecture. The composite structure integrates the advantages of both materials: graphite's high theoretical capacity (372 mAh/g) and hard carbon's ability to accommodate sodium ions. The interface between the two materials also facilitates sodium ion transport.
2Reliability
If hard carbon materials are used as anode, then electrochemical activity towards sodium is improved, but irreversible capacity loss occurs due to SEI layer formation
Solution Approach 1:
The patent applies parameter changes by controlling the surface properties of the hard carbon shell, specifically engineering the micropore surface area to 0-5 m²/g and surface oxygen content to 0-2.5 atm.%. These parameter optimizations reduce excessive SEI formation while maintaining good electrochemical activity, thereby minimizing irreversible capacity loss.
3Ease of manufacture
If plant-derived materials are carbonised to produce hard carbon, then anode material is obtained, but high moisture sensitivity and handling difficulty result
Solution Approach 1:
The patent applies this principle by forming a thin film shell of carbonised material around the plant-derived core. This shell acts as a protective barrier that reduces moisture sensitivity and improves handling characteristics, while the core retains the benefits of sustainable plant-derived materials.
Solution Approach 2:
The patent converts the inherent moisture sensitivity of plant-derived materials into a benefit by using it as a precursor for creating a porous carbon structure. The controlled carbonisation process transforms the moisture-prone organic material into a stable hard carbon shell with reduced moisture sensitivity, while the original moisture content aids in forming the desired micropore structure.
4Duration of action of stationary object
If surface engineering is applied to control SEI layer, then cycling stability is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent applies self-service by using the plant-derived material's own composition to generate the desired surface properties through controlled carbonisation. The organic precursors within the plant material carbonise to form the hard carbon shell with appropriate micropore structure and surface oxygen content, eliminating the need for separate surface engineering 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 surface-engineered anode materials exhibit improved reversible specific capacity, reduced irreversible capacity, enhanced cycling stability, and decreased moisture sensitivity, leading to more efficient energy storage and handling characteristics compared to conventional materials.
Implementation Method 1
optimised through chemical vapour deposition to control the SEI layer's stability
Implementation Method 2
When a sodium-ion (or lithium-ion) battery is charging, Na+ (or Li+) ions are extracted from the cathode and insert into the anode
Implementation Method 3
an outer surface comprising one or more carbonised materials, preferably chemically bonded on the one or more primary carbon-containing materials
Data Source
AI summary
The invention relates to a carbon-containing anode material which is capable of the insertion and extraction of alkali metal ions and which has a carbon structure comprising a core comprising one or more primary carbon-containing materials. The invention further relates to the preparation of such carbon-containing anode material.