The way to improve the energy density of supercapacitors: Progress and perspective

Armand M, Tarascon JM. Building better batteries. Nature, 2008, 451: 652–657

Miller JR, Simon P. Materials science: electrochemical capacitors for energy management. Science, 2008, 321: 651–652

Bonaccorso F, Colombo L, Yu G, et al. Graphene, related twodimensional crystals, and hybrid systems for energy conversion and storage. Science, 2015, 347: 1246501–1246501

Li W, Zeng L, Wu Y, et al. Nanostructured electrode materials for lithium-ion and sodium-ion batteries via electrospinning. Sci China Mater, 2016, 59: 287–321

Simon P, Gogotsi Y. Materials for electrochemical capacitors. Nat Mater, 2008, 7: 845–854

Wang G, Zhang L, Zhang J. A review of electrode materials for electrochemical supercapacitors. Chem Soc Rev, 2012, 41: 797–828

Yan J, Wang Q, Wei T, et al. Recent advances in design and fabrication of electrochemical supercapacitors with high energy densities. Adv Energy Mater, 2014, 4: 1300816

Wu S, Zhu Y. Highly densified carbon electrode materials towards practical supercapacitor devices. Sci China Mater, 2017, 60: 25–38

Béguin F, Presser V, Balducci A, et al. Carbons and electrolytes for advanced supercapacitors. Adv Mater, 2014, 26: 2219–2251

Hao L, Li X, Zhi L. Carbonaceous electrode materials for supercapacitors. Adv Mater, 2013, 25: 3899–3904

Largeot C, Portet C, Chmiola J, et al. Relation between the ion size and pore size for an electric double-layer capacitor. J Am Chem Soc, 2008, 130: 2730–2731

Zhu Y, Murali S, Stoller MD, et al. Carbon-based supercapacitors produced by activation of graphene. Science, 2011, 332: 1537–1541

Hou J, Cao T, Idrees F, et al. A co-sol-emulsion-gel synthesis of tunable and uniform hollow carbon nanospheres with interconnected mesoporous shells. Nanoscale, 2016, 8: 451–457

Xu J, Tan Z, Zeng W, et al. A hierarchical carbon derived from sponge-templated activation of graphene oxide for high-performance supercapacitor electrodes. Adv Mater, 2016, 28: 5222–5228

Kim TY, Jung G, Yoo S, et al. Activated graphene-based carbons as supercapacitor electrodes with macro- and mesopores. ACS Nano, 2013, 7: 6899–6905

Sevilla M, Fuertes AB. Direct synthesis of highly porous interconnected carbon nanosheets and their application as high-performance supercapacitors. ACS Nano, 2014, 8: 5069–5078

Wang H, Xu Z, Kohandehghan A, et al. Interconnected carbon nanosheets derived from hemp for ultrafast supercapacitors with high energy. ACS Nano, 2013, 7: 5131–5141

Xu Y, Lin Z, Zhong X, et al. Holey graphene frameworks for highly efficient capacitive energy storage. Nat Commun, 2014, 5: 4554

Li Y, Li Z, Shen PK. Simultaneous formation of ultrahigh surface area and three-dimensional hierarchical porous graphene-like networks for fast and highly stable supercapacitors. Adv Mater, 2013, 25: 2474–2480

Lin T, Chen IW, Liu F, et al. Nitrogen-doped mesoporous carbon of extraordinary capacitance for electrochemical energy storage. Science, 2015, 350: 1508–1513

Chen LF, Zhang XD, Liang HW, et al. Synthesis of nitrogen-doped porous carbon nanofibers as an efficient electrode material for supercapacitors. ACS Nano, 2012, 6: 7092–7102

Xia W, Qu C, Liang Z, et al. High-performance energy storage and conversion materials derived from a single metal–organic framework/ graphene aerogel composite. Nano Lett, 2017, 17: 2788–2795

Zhang W, Xu C, Ma C, et al. Nitrogen-superdoped 3D graphene networks for high-performance supercapacitors. Adv Mater, 2017, 29: 1701677

Qie L, Chen W, Xu H, et al. Synthesis of functionalized 3D hierarchical porous carbon for high-performance supercapacitors. Energy Environ Sci, 2013, 6: 2497

Zhong M, Kim EK, McGann JP, et al. Electrochemically active nitrogen-enriched nanocarbons with well-defined morphology synthesized by pyrolysis of self-assembled block copolymer. J Am Chem Soc, 2012, 134: 14846–14857

Guo DC, Mi J, Hao GP, et al. IL C16mimBF4 assisted synthesis of poly(benzoxazine-co-resol)-based hierarchically porous carbons with superior performance in supercapacitors. Energy Environ Sci, 2013, 6: 652–659

Hou J, Cao C, Idrees F, et al. Hierarchical porous nitrogen-doped carbon nanosheets derived from silk for ultrahigh-capacity battery anodes and supercapacitors. ACS Nano, 2015, 9: 2556–2564

Qian W, Sun F, Xu Y, et al. Human hair-derived carbon flakes for electrochemical supercapacitors. Energy Environ Sci, 2014, 7: 379–386

Hou J, Cao C, Ma X, et al. From rice bran to high energy density supercapacitors: a new route to control porous structure of 3D carbon. Sci Rep, 2015, 4: 7260

Zhu J, Shan Y, Wang T, et al. A hyperaccumulation pathway to three-dimensional hierarchical porous nanocomposites for highly robust high-power electrodes. Nat Commun, 2016, 7: 13432

Hou J, Jiang K, Tahir M, et al. Tunable porous structure of carbon nanosheets derived from puffed rice for high energy density supercapacitors. J Power Sources, 2017, 371: 148–155

Kang D, Liu Q, Gu J, et al. “Egg-box”-assisted fabrication of porous carbon with small mesopores for high-rate electric double layer capacitors. ACS Nano, 2015, 9: 11225–11233

Hou J, Jian K, Wei R, et al. Popcorn-derived porous carbon flakes with an ultrahigh specific surface area for superior performance supercapacitors. ACS Appl Mater Interfaces, 2017, 9: 30626–30634

Chen C, Zhang Y, Li Y, et al. All-wood, low tortuosity, aqueous, biodegradable supercapacitors with ultra-high capacitance. Energy Environ Sci, 2017, 10: 538–545

Biswal M, Banerjee A, Deo M, et al. From dead leaves to high energy density supercapacitors. Energy Environ Sci, 2013, 6: 1249

Zhao Y, Liu J, Horn M, et al. Recent advancements in metal organic framework based electrodes for supercapacitors. Sci China Mater, 2018, 61: 159–184

Sheberla D, Bachman JC, Elias JS, et al. Conductive MOF electrodes for stable supercapacitors with high areal capacitance. Nat Mater, 2017, 16: 220–224

Khalid S, Cao C, Wang L, et al. Microwave assisted synthesis of porous NiCo2O4 microspheres: application as high performance asymmetric and symmetric supercapacitors with large areal capacitance. Sci Rep, 2016, 6: 22699

Mahmood N, Tahir M, Mahmood A, et al. Chlorine-doped carbonated cobalt hydroxide for supercapacitors with enormously high pseudocapacitive performance and energy density. Nano Energy, 2015, 11: 267–276

Ali Z, Tahir M, Cao C, et al. Solid waste for energy storage material as electrode of supercapacitors. Mater Lett, 2016, 181: 191–195

Salunkhe RR, Kaneti YV, Yamauchi Y. Metal–organic frameworkderived nanoporous metal oxides toward supercapacitor applications: progress and prospects. ACS Nano, 2017, 11: 5293–5308

Idrees F, Hou J, Cao C, et al. Template-free synthesis of highly ordered 3D-hollow hierarchical Nb2O5 superstructures as an asymmetric supercapacitor by using inorganic electrolyte. Electrochim Acta, 2016, 216: 332–338

Zhang X, Zhang H, Lin Z, et al. Recent advances and challenges of stretchable supercapacitors based on carbon materials. Sci China Mater, 2016, 59: 475–494

Hao J, Peng S, Qin T, et al. Fabrication of hybrid Co3O4/NiCo2O4 nanosheets sandwiched by nanoneedles for high-performance supercapacitors using a novel electrochemical ion exchange. Sci China Mater, 2017, 60: 1168–1178

Khalid S, Cao C, Wang L, et al. A high performance solid state asymmetric supercapacitor device based upon NiCo2O4 nanosheets//MnO2 microspheres. RSC Adv, 2016, 6: 70292–70302

Zhu Y, Cao C, Tao S, et al. Ultrathin nickel hydroxide and oxide nanosheets: synthesis, characterizations and excellent supercapacitor performances. Sci Rep, 2015, 4: 5787

Khalid S, Cao C, Naveed M, et al. 3D hierarchical MnO2 microspheres: a prospective material for high performance supercapacitors and lithium-ion batteries. Sustain Energy Fuels, 2017, 1: 1795–1804

Zheng C, Cao C, Chang R, et al. Hierarchical mesoporous NiCo2O4 hollow nanocubes for supercapacitors. Phys Chem Chem Phys, 2016, 18: 6268–6274

Khalid S, Cao C, Ahmad A, et al. Microwave assisted synthesis of mesoporous NiCo2O4 nanosheets as electrode material for advanced flexible supercapacitors. RSC Adv, 2015, 5: 33146–33154

Choudhary N, Li C, Moore J, et al. Asymmetric supercapacitor electrodes and devices. Adv Mater, 2017, 29: 1605336

Zheng M, Xiao X, Li L, et al. Hierarchically nanostructured transition metal oxides for supercapacitors. Sci China Mater, 2018, 61: 185–209

Yan J, Fan Z, Sun W, et al. Advanced asymmetric supercapacitors based on Ni(OH)2/graphene and porous graphene electrodes with high energy density. Adv Funct Mater, 2012, 22: 2632–2641

Owusu KA, Qu L, Li J, et al. Low-crystalline iron oxide hydroxide nanoparticle anode for high-performance supercapacitors. Nat Commun, 2017, 8: 14264

Boruah BD, Misra A. Internal asymmetric tandem supercapacitor for high working voltage along with superior rate performance. ACS Energy Lett, 2017, 2: 1720–1728

Kim M, Kim J. Development of high power and energy density microsphere silicon carbide–MnO2 nanoneedles and thermally oxidized activated carbon asymmetric electrochemical supercapacitors. Phys Chem Chem Phys, 2014, 16: 11323

Qiu Y, Li G, Hou Y, et al. Vertically aligned carbon nanotubes on carbon nanofibers: a hierarchical three-dimensional carbon nanostructure for high-energy flexible supercapacitors. Chem Mater, 2015, 27: 1194–1200

Liu C, Yu Z, Neff D, et al. Graphene-based supercapacitor with an ultrahigh energy density. Nano Lett, 2010, 10: 4863–4868

Hwang JY, El-Kady MF, Wang Y, et al. Direct preparation and processing of graphene/RuO2 nanocomposite electrodes for highperformance capacitive energy storage. Nano Energy, 2015, 18: 57–70

Wu ZS, Ren W, Wang DW, et al. High-energy MnO2 nanowire/ graphene and graphene asymmetric electrochemical capacitors. ACS Nano, 2010, 4: 5835–5842

Ji J, Zhang LL, Ji H, et al. Nanoporous Ni(OH)2 thin film on 3D ultrathin-graphite foam for asymmetric supercapacitor. ACS Nano, 2013, 7: 6237–6243

Zuo W, Li R, Zhou C, et al. Battery-supercapacitor hybrid devices: recent progress and future prospects. Adv Sci, 2017, 4: 1600539

Li B, Dai F, Xiao Q, et al. Nitrogen-doped activated carbon for a high energy hybrid supercapacitor. Energy Environ Sci, 2016, 9: 102–106

Lim E, Jo C, Kim H, et al. Facile synthesis of Nb2O5@Carbon core–shell nanocrystals with controlled crystalline structure for highpower anodes in hybrid supercapacitors. ACS Nano, 2015, 9: 7497–7505

Wang Y, Luo J, Wang C, et al. Hybrid aqueous energy storage cells using activated carbon and lithium-ion intercalated compounds. J Electrochem Soc, 2006, 153: A1425

Shen L, Lv H, Chen S, et al. Peapod-like Li3VO4/N-doped carbon nanowires with pseudocapacitive properties as advanced materials for high-energy lithium-ion capacitors. Adv Mater, 2017, 29: 1700142

Ding J, Wang H, Li Z, et al. Peanut shell hybrid sodium ion capacitor with extreme energy–power rivals lithium ion capacitors. Energy Environ Sci, 2015, 8: 941–955

Jabeen N, Hussain A, Xia Q, et al. High-performance 2.6 V aqueous asymmetric supercapacitors based on in situ formed Na0.5MnO2 nanosheet assembled nanowall arrays. Adv Mater, 2017, 29: 1700804

Peng S, Li L, Wu HB, et al. Controlled growth of NiMoO4 nanosheet and nanorod arrays on various conductive substrates as advanced electrodes for asymmetric supercapacitors. Adv Energy Mater, 2015, 5: 1401172

Li R, Wang Y, Zhou C, et al. Carbon-stabilized high-capacity ferroferric oxide nanorod array for flexible solid-state alkaline battery-supercapacitor hybrid device with high environmental suitability. Adv Funct Mater, 2015, 25: 5384–5394

Li K, Zhang J. Recent advances in flexible supercapacitors based on carbon nanotubes and graphene. Sci China Mater, 2018, 61: 210–232

Qin J, Zhou F, Xiao H, et al. Mesoporous polypyrrole-based graphene nanosheets anchoring redox polyoxometalate for all-solidstate micro-supercapacitors with enhanced volumetric capacitance. Sci China Mater, 2018, 61: 233–242

Zhang J, Zhao XS. On the configuration of supercapacitors for maximizing electrochemical performance. ChemSusChem, 2012, 5: 818–841