{
    "title": "NanoHemp SuperCapacitor",
    "inventor_name": "David Mitlin et al.",
    "publication_year": 2013,
    "device_name": "Hemp-based SuperCapacitor",
    "goal": "Provide a low-cost, high-performance energy-storage device that can replace expensive graphene electrodes in supercapacitors.",
    "problem_addressed": "The high price and limited scalability of graphene-based electrodes for high-power energy storage.",
    "concept_summary": "Waste hemp bast fibers are hydrothermally carbonized and chemically activated to produce porous carbon nanosheets that mimic graphene. These nanosheets are used as electrodes in a supercapacitor with an ionic-liquid electrolyte, delivering high power and energy densities at a fraction of the cost of graphene.",
    "detailed_description": "The process begins with hemp bast (inner bark) that is heated at ~180  deg C for 24 h to dissolve lignin and hemicellulose, leaving a carbonized matrix. The material is then treated with potassium hydroxide and heated to 700-800  deg C, causing exfoliation into porous carbon nanosheets (2-5 nm pores). The nanosheets are fabricated into electrodes and combined with an ionic liquid electrolyte to assemble a supercapacitor. Laboratory tests show operation from -0  deg C to 100  deg C, power densities up to 49 kW kg^-^1 at 60  deg C, and energy densities of 19-40 Wh kg^-^1 depending on temperature, with a full-device energy density of 12 Wh kg^-^1 and charge times under six seconds.",
    "category": "Nanotechnology",
    "principles": [
        "Hydrothermal carbonization",
        "Chemical activation (KOH)",
        "Electrical double-layer capacitance",
        "High-surface-area porous carbon electrodes"
    ],
    "scientific_domains": [
        "Materials Science",
        "Chemical Engineering",
        "Electrochemistry",
        "Nanotechnology"
    ],
    "mechanisms_of_action": [
        "Ion adsorption/desorption on porous carbon surfaces",
        "Rapid charge transfer through high-conductivity carbon nanosheets"
    ],
    "materials": [
        "Hemp bast fiber (lignin, hemicellulose, cellulose)",
        "Carbon nanosheets (derived from hemp)",
        "Potassium hydroxide (KOH)",
        "Ionic liquid electrolyte"
    ],
    "energy_sources": [
        "Electrical input for charging"
    ],
    "inputs": [
        "Waste hemp bast fibers",
        "Heat (180  deg C, 24 h)",
        "KOH chemical activation",
        "High-temperature treatment (700-800  deg C)",
        "Ionic liquid electrolyte"
    ],
    "outputs": [
        "Stored electrical energy",
        "High-power pulses"
    ],
    "claimed_performance": "Power density up to 49 kW kg^-^1 at 60  deg C; energy density 19-40 Wh kg^-^1 (20-100  deg C); full device energy density 12 Wh kg^-^1 with charge time <6 s.",
    "experimental_evidence": "Peer-reviewed ACS Nano paper (2013) reports the performance metrics; Chemical & Engineering News article (May 15 2013) describes the synthesis and testing; data tables quoted in the article.",
    "replication_status": null,
    "keywords": [
        "hemp",
        "carbon nanosheets",
        "supercapacitor",
        "graphene-like",
        "bio-waste",
        "energy storage",
        "ionic liquid"
    ],
    "related_technologies": [
        "Graphene supercapacitors",
        "Activated-carbon supercapacitors",
        "Bio-waste derived electrode materials"
    ],
    "controversy_level": "low",
    "confidence_score": 0.9,
    "practicability_score": 0.7,
    "fringe_score": 0.2,
    "evidence_strength": 0.6,
    "risk_score": 0.1,
    "trl_estimate": 5,
    "source_urls": [
        "http://www.bbc.co.uk/news/science-environment-28770876",
        "http://cen.acs.org/articles/91/web/2013/05/Energy-Storing-Nanomaterial-Made-Hemp.html",
        "http://pubs.acs.org/doi/abs/10.1021/nn400731g",
        "http://www.altasupercaps.com/",
        "http://www.leafscience.com/2013/10/01/top-5-innovative-uses-hemp/"
    ],
    "organizations": [
        "Clarkson University",
        "University of Alberta",
        "Alta Supercaps"
    ],
    "applications": [
        "Electric vehicles (regenerative braking)",
        "Power-tool electronics",
        "Oil-and-gas industry equipment (high-temperature operation)",
        "Portable high-power devices"
    ],
    "limitations": [
        "High-temperature (700-800  deg C) activation step may be costly at scale",
        "Reliance on ionic-liquid electrolytes, which can be expensive",
        "Long-term cycle life not yet demonstrated",
        "Scaling from lab-scale to commercial production not proven"
    ],
    "open_questions": [
        "Can the process be optimized to lower energy consumption?",
        "What is the commercial cost comparison with activated-carbon electrodes?",
        "How does the device perform over thousands of charge-discharge cycles?",
        "Are there environmentally benign alternatives to KOH activation?"
    ],
    "red_flags": [],
    "evidence_quotes": [
        "\"...we made supercapacitors which operate at a broad range of temperatures and a high energy density.\"",
        "\"At a very high power density of 20 kW/kg and temperatures of 20, 60, and 100  deg C, the energy densities are 19, 34, and 40 Wh/kg respectively.\"",
        "\"Fully assembled, their energy density is 12 Wh/kg, which can be achieved at a charge time less than six seconds.\"",
        "\"The material puts out 49 kW/kg at 60  deg C, compared with 17 kW/kg for activated carbon commercial electrodes.\"",
        "\"They work down to 0  deg C and display some of the best power-energy combinations reported in the literature for any carbon.\""
    ]
}