A novel energy storage system incorporating electrically rechargeable liquid fuels as the storage medium.

We propose a novel concept of energy storage that incorporates electrically rechargeable liquid fuels made of electroactive species, known as e-fuels, as the storage medium. This e-fuel energy storage system comprises an e-fuel charger and an e-fuel cell. The e-fuel charger electrically charges e-fuels, while the e-fuel cell subsequently generates electricity using charged e-fuels whenever and wherever on demand. The e-fuel energy storage system possesses all the advantages of conventional hydrogen storage systems, but unlike hydrogen, liquid e-fuels are as easy and safe to store and transport as gasoline. The potential e-fuel candidates have been identified to include inorganic electroactive materials, organic electroactive materials, and suspension of solid electroactive materials. In this work, we demonstrate an example e-fuel energy storage system for large-scale energy storage using inorganic e-fuels composed of V2+/V3+ and VO2+/VO2+ redox couples, and compare the performance of the e-fuel energy storage system with that of existing technologies. Results show that our e-fuel charger achieves a charge efficiency of as high as ∼94%, while the e-fuel cell is capable of delivering a peak power density of 3.4 W cm−2, which is 1.7 times higher than that of hydrogen fuel cells. More excitingly, the e-fuel energy storage system exhibits a round-trip efficiency of 80.0% and an electrolyte utilization of 83.0% at an ultra-high discharge current density of 1,000 mA cm−2, which are 19.9% and 67.3% higher than those of conventional vanadium redox flow batteries. This unprecedented performance allows a 27.0% reduction in the capital cost of the e-fuel energy storage system compared with that of vanadium redox flow batteries.

[1]  Wei Shyy,et al.  Highly active, bi-functional and metal-free B4C-nanoparticle-modified graphite felt electrodes for vanadium redox flow batteries , 2017 .

[2]  M. Shao,et al.  Fe3C Nanorods Encapsulated in N-Doped Carbon Nanotubes as Active Electrocatalysts for Hydrogen Evolution Reaction , 2018, Electrocatalysis.

[3]  Haisheng Chen,et al.  Progress in electrical energy storage system: A critical review , 2009 .

[4]  Xavier Gonze,et al.  A brief introduction to the ABINIT software package , 2005 .

[5]  Guosong Hong,et al.  Advanced zinc-air batteries based on high-performance hybrid electrocatalysts , 2013, Nature Communications.

[6]  Rong Chen,et al.  A novel direct ethanol fuel cell with high power density , 2011 .

[7]  R. Schweiss,et al.  Parasitic Hydrogen Evolution at Different Carbon Fiber Electrodes in Vanadium Redox Flow Batteries , 2016 .

[8]  T. Zhao,et al.  A bi-porous graphite felt electrode with enhanced surface area and catalytic activity for vanadium redox flow batteries , 2019, Applied Energy.

[9]  Jianguo Liu,et al.  Reduced graphene oxide with tunable C/O ratio and its activity towards vanadium redox pairs for an all vanadium redox flow battery , 2013 .

[10]  Roland Zengerle,et al.  Direct deposition of proton exchange membranes enabling high performance hydrogen fuel cells , 2015 .

[11]  Joshua M. Pearce,et al.  A Review of Solar Photovoltaic Levelized Cost of Electricity , 2011 .

[12]  Frank C. Walsh,et al.  Dynamic modelling of hydrogen evolution effects in the all-vanadium redox flow battery , 2010 .

[13]  M. Shao,et al.  The Role of Transition Metal and Nitrogen in Metal–N–C Composites for Hydrogen Evolution Reaction at Universal pHs , 2016 .

[14]  Bin Li,et al.  Comparative analysis for various redox flow batteries chemistries using a cost performance model , 2015 .

[15]  Lu Yue,et al.  Highly hydroxylated carbon fibres as electrode materials of all-vanadium redox flow battery , 2010 .

[16]  D. J. Durbin,et al.  Review of hydrogen storage techniques for on board vehicle applications , 2013 .

[17]  Bin Li,et al.  Cost and performance model for redox flow batteries , 2014 .

[18]  D. J. Swider,et al.  Compressed Air Energy Storage in an Electricity System With Significant Wind Power Generation , 2007, IEEE Transactions on Energy Conversion.

[19]  Daniel Bodansky,et al.  The Paris Climate Change Agreement: A New Hope? , 2016, American Journal of International Law.

[20]  M. Armand,et al.  Issues and challenges facing rechargeable lithium batteries , 2001, Nature.

[21]  Xuelong Zhou,et al.  A comparative study of all-vanadium and iron-chromium redox flow batteries for large-scale energy storage , 2015 .

[22]  Qi Feng,et al.  A review of proton exchange membrane water electrolysis on degradation mechanisms and mitigation strategies , 2017 .

[23]  L. Jörissen,et al.  The application of covalently cross-linked BrPPO as AEM in alkaline DMFC , 2013 .

[24]  Emin Caglan Kumbur,et al.  Open circuit voltage of vanadium redox flow batteries: Discrepancy between models and experiments , 2011 .

[25]  Grace Ordaz,et al.  The U.S. Department of Energy's National Hydrogen Storage Project: Progress towards meeting hydrogen-powered vehicle requirements , 2007 .

[26]  T. Zhao,et al.  Highly efficient and ultra-stable boron-doped graphite felt electrodes for vanadium redox flow batteries , 2018 .

[27]  Eamon McKeogh,et al.  Techno-economic review of existing and new pumped hydro energy storage plant , 2010 .

[28]  G. Soloveichik.  Flow Batteries: Current Status and Trends. , 2015, Chemical reviews.

[29]  Jae‐Hun Kim,et al.  The effects of surface modification on carbon felt electrodes for use in vanadium redox flow batteries , 2011 .

[30]  Hartmut Spliethoff,et al.  Current status of water electrolysis for energy storage, grid balancing and sector coupling via power-to-gas and power-to-liquids: A review , 2018 .

[31]  Ulrich Eberle,et al.  Hydrogen storage: the remaining scientific and technological challenges. , 2007, Physical Chemistry, Chemical Physics - PCCP.

[32]  T. Zhao,et al.  Unraveling the Positive Roles of Point Defects on Carbon Surfaces in Nonaqueous Lithium–Oxygen Batteries , 2016 .

[33]  G. Kresse,et al.  From ultrasoft pseudopotentials to the projector augmented-wave method , 1999 .

[34]  T. Zhao,et al.  Towards a Uniform Distribution of Zinc in The Negative Electrode for Zinc Bromine Flow Batteries , 2018 .

[35]  Bin Li,et al.  Capacity decay and remediation of nafion-based all-vanadium redox flow batteries. , 2013, ChemSusChem.

[36]  Matthieu Verstraete,et al.  First-principles computation of material properties: the ABINIT software project , 2002 .

[37]  Burke,et al.  Generalized Gradient Approximation Made Simple. , 1996, Physical review letters.

[38]  Yinshi Li,et al.  Insight into Interface Behaviors to Build Phase-Boundary-Matched Na-Ion Direct Liquid Fuel Cells , 2018, ACS Sustainable Chemistry & Engineering.

[39]  C. Dennison,et al.  Identification of performance limiting electrode using asymmetric cell configuration in vanadium redox flow batteries , 2013 .

[40]  Lili Zhang,et al.  Carbon-based materials as supercapacitor electrodes. , 2009, Chemical Society reviews.