\”Polymer\” met \”nano-energy\”! Powerful combination, Stanford \”Gemini\” Classic Review Cui Yi and Bao Zhenan those years
Lift the field of materials Daniel, professor Yi Cui \”Gemini\” Stanford University and Professor Bao Zhenan certain list. Both with Chinese scientists at Stanford University, engrossed in a nano-energy battery technology, a focus on artificial intelligence electronic skin, published in their respective fields Niu too numerous to mention. Today we are going to talk about Professor Professor Cui Yihe Bao Zhenan two in the way of scientific research \”bond.\” the two first collaboration began in 2011. Lucky coincidence, two collaborative research nanocomposite electrode material, by a porous textile fibrous graphene immersed in the solution, and further electrodeposition using a load of MnO2, resulting nanocomposite electrode material has a long cycle life, high capacitance. The work attracted the attention of many researchers, but also highlight \”Nature\” magazine, far citations up to 990 times. After succeed and cooperation of the two will not be closed, research involving oxides,, lithium-sulfur battery, the negative electrode and the polymer electrolyte silicon, and many other fields, and each one is a classic! It is no exaggeration to say that the god Yi Cui senior accomplishments in the field of energy storage, plus Bao Zhenan goddess excellence in organic, field of polymer materials, powerful alliances, to inject new vitality into battery technology, allowing electrical energy storage field to achieve again and again to break! first collaboration Cui Yi Bao Zhenan great God and Goddess. . Source: Nano Lett 2011, 11, 7, 2905-2911 following small briefly reviews the 2013 – 2020 of important research results Professor Cui Yihe Bao Zhenan two strong cooperation. Due to space limitations, only the top journals include both common and related work Corresponding author:……
Part1 Part2 lithium metal polymer electrolyte lithium-sulfur battery cells Part3 Part4 Part5 silicon anode lithium ion battery sodium ion battery heat Part6 switch-sensitive polymeric material
Part 1. the polymer electrolyte
1 JACS:. a high electrochemical stability novel ion-conductive electrolyte fluorinated ether
remain stable lithium metal deposition / ion release and highMeanwhile conductivity, improve the oxidative stability of the electrolyte is a huge challenge. Accordingly, an urgent need for the design and synthesis of new electrolytes, such as high oxidation stability of the ether solvent with high ionic conductivity hydrofluoroether combined to support high voltage and lithium metal cathode. To address this challenge, Professor Yi Cui of Stanford University and Professor Bao Zhenan team jointly designed a new method for the synthesis of novel fluorinated ethers electrolyte, that is, through the core and fluorinated ethers \”end group\” covalently bonded to achieve a single electrolyte uniform conductivity and high oxidation stability in high ionic. Meanwhile, in a modular fashion to change the length and type of an ether group, a fluorinated segments and a length, a systematic study of this new electrolyte structure – nature of the relationship. When found, the new electrolyte prepared fluorinated ether ether having a longer and a shorter group segment fluorinated ionic conductivity as high as 2.7 × 10-4 S / cm (at 30 ° C), and having voltage up to 5.6 V oxide. Nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations show that with increasing shorter segments and ether segments fluorine, fluorinated ethers ion conductivity increases. The researchers further electrolyte to the high-voltage battery Li-NMC 811, the battery can be stably assembled cycles or more under the magnification of 100 times as high as the C / 5. Reference: A new class of ionically conducting fluorinated ether electrolyteswith high electrochemical stability J. Am Chem Soc 2020. DOI:…. 10.1021 / jacs.9b11056 link description: https: //pubs.acs. between org / doi / abs / 10.1021 / jacs.9b11056
2. Adv. Energy Mater .: nonpolar alkane improved lithium metal anode electrolyte interface additives
of lithium metal and the electrolyte the side effects will lead to lower coulombic efficiency of the battery, a sharp decline in battery performance. Hence the need to develop non-reactive electrolyte addedAgent to reduce the surface concentration of the electrolyte solvent, a lithium metal / electrolyte interface, while permanently present in the cell and maintaining the concentration substantially constant. In view of this, Stanford University professor Baozhe Nan Yi Cui Professor jointly report a non-polar alkane as lithium battery electrolyte is non-reactive additives. Studies have shown that, to add alkane to the ether solvent only lithium nucleation overpotential deposition and growth can be halved, increasing the battery coulombic efficiency of lithium deposition and improved morphology, improves the oxidation stability of the electrolyte, and cycle life expectancy has doubled. Mainly due to enhanced electrochemical properties, a non-polar alkane solvent environment changes and reduces lithium ions solvation free energy, thus reducing the reaction of lithium deposited barrier. Meanwhile, the work has demonstrated, to explore the performance as a non-polar alkane and the control mechanism is an excellent additive for electrolyte of lithium metal deposition strategy. Reference: Nonpolar Alkanes Modify Lithium-Ion Solvation for Improved Lithium Depositionand Stripping Adv Energy Mater.2019, DOI:… 10.1002 / aenm.201902116 link description: https://onlinelibrary.wiley.com/ doi / full / 10.1002 / aenm.201902116
3. Nat. Commun .: ionic conductivity and mechanical properties of both the lithium ion conductor supramolecular
the wearable electronic rapidly growing demand for the electrode material of a higher requirements, for example requiring superior mechanical strength, tensile properties and ionic conductivity of the polymer electrolyte. To address this challenge, Bao Zhenan professor at Stanford University, and Shanghai Jiaotong University professor Yi Cui Yan Xuzhou researcher (co-author), who reported that a joint strategy for the effective ionic conductivity and mechanical strength of the polymer electrolyte decoupling, and We designed a supramolecular lithium ion conductor (SLIC). Wherein the polyether backbone has a low Tg unit provides ionic conductivity, and the dynamic key coupling 2-ureido -4- pyrimidone (UPy) backbone units provide mechanical properties to obtain a polymer having an ion conductivity of 1.2 ± 0.21 × 10-4 S cm-1 at 29.3 ± 1.4 and superior toughness at room temperature is M Jm-3 electrolyte. In addition, researchers prepared supramolecular lithium ion conductor into the adhesive material, using a stretchable conventional lithium ion battery electrode slurry preparation process of the resilience of more than 900 percent. Supramolecular nature of these cell components so that they can be at the electrode – electrolyte interface tight binding. Using these components to build a scalable battery capacity of up to 1.1 mAh cm-2, normal operation is maintained even at 70% strain conditions. Methods ionic conductivity and mechanical properties of the separation of the work reported for preparing high toughness ion energy storage material transport has opened up a promising approach. Reference: Decoupling of mechanical properties and ionic conductivity insupramolecular lithium ion conductors Nat Commun 10, 5384 (2019) DOI:…. 10.1038 / s41467-019-13362-4 link description: https: // www.nature.com/articles/s41467-019-13362-4
4. Energy Environ. Sci .: green, low-cost acetate mixture was concentrated \”salt water\” aqueous cell electrolyte
the electrolyte is an important component of the energy storage device. Electrolyte components have a significant impact on safety, the price and performance of the battery. Essentially nonflammable aqueous electrolyte battery can provide more secure operations, and reduce associated toxicity, but compared with the conventional organic electrolyte electrochemical stability window (and energy density) is smaller. While the recently proposed high concentration of \”salt water\” provides an extended electrolyte electrochemical stability window, but the lack of sufficient water soluble lithium salt water conditions, select only limited and costly toxic organic imide .In response to the challenge to develop new water-salt electrolyte formulations, Professor Yi Cui of Stanford University and Professor Bao Zhenan proposed a mixed-cation strategy, namely the use of the high solubility of potassium acetate in water with cationic molar ratio of lithium as low as 1.3 and a eutectic mixture of potassium acetate reached WIS conditions. The study found a high concentration of the electrolyte potassium acetate group and an imide group may provide the same voltage range extended the advantages of the electrolyte, and may be a conventional lithium ion battery electrode material compatibility, low cost and environmentally benign simultaneously. This work is safe, practical and low-cost high performance aqueous lithium-ion batteries provide important direction. Reference: Concentrated mixed cation acetate \”water-in-salt\” solutions as greenand low-cost high voltage electrolytes for aqueous batteries Energy Environ.Sci, 2018, 11, 2876-2883 DOI:… 10.1039 / C8EE00833G. original link:.. https://pubs.rsc.org/no/content/articlehtml/2018/ee/c8ee00833g
5 Adv Energy Mater .: crosslinked poly (tetrahydrofuran) as a fluffy with bit security and performance of the polymer electrolyte
the solid polymer electrolyte (SPE) lithium ion batteries is expected to greatly improve (the LIB) is. However, based on a conventional polyethylene oxide (PEO) facing the SPE lower ionic conductivity and mobility problems, which hinder further commercial applications. In view of this, Stanford University Professor and Professor Cui Yi Bao Zhenan (co-author) the introduction of cross-linked poly tetrahydrofuran (xPTHF) as \”beyond PEO\” loose coordination of high performance SPE. Compared with conventional systems xPEO, xPTHF having high metastatic 0.53, good electrochemical stability and higher lithium conductivity. In addition, xPTHF10 SPE at a temperature up to 234 ° C also exhibit good thermal stability, and a flexible, independent, easy processing dimensions. When incorporated in an all-solid-state battery LFP having xPTHF10 SPE cells exhibit specific capacity 162 mAh g-1 and at 70 ° C for 1C rate. Molecular additive (e.g. DMF and PC) Li + may be further adjusted coordination environment, so xPTHF5DMF2: 1-yl SPE room temperature ionic conductivity reaches 1.2 × 10-4 S cm-1. Further plasticized xPTHF SPE solid fulfill LFP battery assembly, it may have up to 129 mAh g-1 specific capacity at room temperature and rate of C / 10. References: Crosslinked Poly (tetrahydrofuran) as a Loosely Coordinating PolymerElectrolyte Adv Energy Mater 2018, 8, 1800703. DOI:… 10.1002 / aenm.201800703 link description: https://onlinelibrary.wiley.com /doi/full/10.1002/aenm.201800703
6. Adv. Mater .: double crosslinked design flexibility lithium ion conductor
There is currently a great challenge to the solid electrolyte and mechanical properties that ion conductivity of perfect unity. In view of this, Professor Yi Cui of Stanford University and Professor Bao Zhenan team for the first time designed a lithium ion conductor having an elastic double covalent cross-linking and dynamic hydrogen bonding, not only has greater flexibility, while not sacrificing room temperature ionic conductivity. Combination of polypropylene oxide elastomers (EPPO) by electrostatic covalent bonds provide elasticity, dynamic sacrificial hydrogen bonding between the amide groups eliminate stress. Before selecting the polyether amine compound because it can be converted to an amide hydrogen bonding, PPO backbone rather than an amorphous form crystalline domains formed by the PEO. The linear diamine is introduced to increase the molecular weight of the crosslinking, reduce the modulus of the material, and the resilience of the neat polymer from250% to 500%. Used as Li / LiFePO4 cell electrolyte and a binder, the assembled battery can operate at a high capacity of the cathode 152 mAh g-1 at room temperature and 300, even after rigorous mechanical shock test, can be kept stable operation . This new design not only provides dual crosslinking powerful mechanical properties of the solid electrolyte, while maintaining the best advanced polymer based electrolyte ion conductivity similar. Even under extreme usage, this method also opens the way to a stable solid state battery, high-performance operation. Reference: A Dual-Crosslinking Design for ResilientLithium-Ion Conductors Adv Mater 2018, 30, 1804142. DOI:… 10.1002 / adma.201804142 link description: https://onlinelibrary.wiley.com/ doi / full / 10.1002 / adma.201804142
Part 2. a lithium metal anode
1 Joule:. dynamic stability of a lithium metal anode, an electrolyte and a single-ion conducting blocking network
[123 ] the development of lithium metal anode has been limited by the heterogeneity and instability of the solid electrolyte formed naturally. Adjusting conformal interface artificial protected by rational design the SEI, the rapid ion migration and inhibition of side reaction formation, an effective strategy for to achieve the desired interface. In view of this, Professor Cui Yi Bao Zhenan and Stanford University jointly designed a new type of artificial SEI, namely dynamic single ion conductive Network (DSN). DSN binding tetrahedral Al (OR) 4- (R = Soft fluorinated linker) center, both dynamic bonding motif, and is a counter anion, and impart fluidity single Li + ion conductivity. Meanwhile, the body providing the electrolyte flow and chain blocking capability connected fluoride. It found, the DSN coating solution may be treated while preventing penetration of the electrolyte, reduce the side reaction between lithium and electrolyte to maintain a low impedance interface, and allows a uniform deposition of lithium. With this coating, Li || A Cu 400 times the battery can complete intercalation / deintercalation cycle, and Li || NMC full cell after 160 cycles still able to maintain 85% of capacity. Reference: A Dynamic, Electrolyte-Blocking, and Single-Ion-Conductive Networkfor Stable Lithium-Metal Anodes Joule 2019, 3, 2761-2776 DOI:… 10.1016 / j.joule.2019.07.025 description link: https://www.sciencedirect.com/science/article/abs/pii/S2542435119303691 2. ACS Energy Lett .: highly viscoelastic polymeric coating booster performance lithium metal anode [123 ]
lithium dendrite growth problems and low coulombic efficiency insurmountable challenges. Fundamentally, these two problems are due to the instability intermediate solid electrolyte (SEI) layer caused by the instability easily be destroyed by a large volume change in the cell cycle. In this work, we show that, when applied to the high viscoelasticity of polymer lithium metal electrode, a lithium deposited morphology becomes more uniform. At high current density 5 mA / cm2, we obtain a flat and dense layer of lithium metal, and at a current density of 1 mA / cm2 was observed stable cycle coulombic efficiency of about 97%, more than 180 can be maintained cycles. Reference: High-Performance Lithium Metal Negative Electrode with a Soft andFlowable Polymer Coating link description:
https://pubs.acs.org/doi/abs/10.1021/acsenergylett.6b00456 3. J.. Soc .: Effect Am. Chem polymer coating on the lithium metal deposition behavior practical application
of lithium metal batteries, there has been dendrite growth, low coulombic efficiency and cycle life And other issues. Although in recent years, researchers have taken many methods to stabilize lithium metal – electrolyte interface, flexible polymeric coating comprising a lithium metal have been possible to realize high-rate cycling performance and high capacity, but further guidance on how rational design or modification of the art of polymerization coatings, there is no clear guidance program. In view of this, Stanford University professor Baozhe Nan Professor Yi Cui Team System The effect of various polymer coatings having different chemical composition and mechanical properties of variable behavior of deposited lithium metal and the polymer dielectric constant, and the surface can be determined two key indicators for the deposition of lithium size. This work provides new insights into the basis lithium electro-deposition process, and provides guidance for the design of new polymer coating to better stabilize lithium metal anode.
Reference: Effects of Polymer Coatings on Electrodeposited Lithium Metal J.Am. Chem Soc 2018, 140, 37, 11735-11744 DOI:….. 10.1021 / jacs.8b06047 link description: https: / /pubs.acs.org/doi/10.1021/jacs.8b060474. J. Am. Chem. Soc .: fluorinated surface to enhance the stability of the active material of the negative electrode of the battery
Li-containing the high capacity negative electrode comprising Li metal and pre-lithiated Si, requires a uniform dense and LiF passivation layer interface, in response to the battery during the preparation cycle and severe corrosion environment. In view of this, Professor Baozhe Nan and Yi Cui Stanford team developed a simple surface fluorination process, as a precursor generated in situ in the reaction of the anode material by using fluorine gas to form a uniform and dense fluoropolymer CYTOP the LiF coating. As an ideal source of fluorine polymer, CYTOP at a lower temperatureDecomposition and release of pure fluorine gas, to avoid direct handling of highly toxic fluorine gas. Also, Li metal anode to provide an interface layer having a chemical stability and mechanical strength, corrosion by reacting with a carbonate type electrolyte is minimized so as to achieve the effect of suppressing dendrite formation of a coated layer of LiF. Thus, LiF-coated Li metal battery at a current density 5mAcm-2, the coil 300 can stabilize the cycle, and no dendrite formation. Further, a dense covering layer and LiF crystals LixSi NPs improved stability in humid air and conventional slurry solvent (NMP) in, LiF-LixSi NPs showed that the electrode manufacturing process and industrial compatibility. Using LiF cladding layer, decomposition of the electrolyte has been effectively suppressed, during a long cycle LiF-LixSiNPs remain high CE (CE average of 99.92% from the third cycle to 650 cycles). This easy surface fluorination process is important to the development of conventional lithium ion batteries and lithium metal batteries of the next generation.
Reference:.. Surface Fluorination of Reactive Battery Anode Materials forEnhanced Stability J. Am Chem Soc, 2017, DOI:.. 10.1021 / jacs.7b05251 link description: https://pubs.acs.org/ doi / abs / 10.1021 / jacs.7b05251 Part 3. Li-ion battery cathode silicon
1. Nat. Commun .: situ polymerization of the conductive polymer hydrogel to achieve high performance silicon anode
silicon anode material because of its high theoretical capacity been widespread concern. However, the charge-discharge process huge volume expansion leads to reduced cycling stability. To solve this problem, Stanford University Professor Cui Yihuo Baozhe Nan by in situ polymerization of Si nanoparticles encapsulated in a porous electrically conductive polymer frame 3D nanostructures to achieve high performance in a lithium ion battery anode. This layered hydrogel frame advantageously combines the plurality of powerEnergy, electrostatic interactions including hydrogen bonding crosslinker continuous conductive polyaniline network polymer with phytic acid or with a positively charged surface-bound Si and the porous Si particle volume expansion space. Silicon anode prepared successfully achieved a high capacity and extremely stable electrochemical cycling, the current density 6.0 A g-1 under continuous deep cycle up to 5,000 times, and more than 90% of the holding capacity. Moreover, solution synthesis, and the electrode manufacturing process is highly scalable, and is compatible with existing slurry coating battery manufacturing technology, high-performance composite electrode for large-scale production.
Reference: Stable Li-ion battery anodes by in-situ polymerization of conductinghydrogel to conformally coat silicon nanoparticles Nat Commun 4, 1943 (2013) DOI:…. 10.1038 / ncomms2941 description link: https: / /www.nature.com/articles/ncomms29412.. .: assist self-healing silicone particles anode Nat Chem microns high energy density lithium batteries
since the ability to repair damage (also known as self-healing) is an important feature of survival in nature, because it can extend the life of most organisms. For rechargeable batteries, because the resulting mechanical failure during cycling will shorten the life of the electrode, such as a high capacity anode silicon or the like, and thus an electrode material having a self-healing feature is equally important. Inspired by nature, Stanford University Professor Cui Yihuo Baozhe Nan the first time the self-healing technique used in silicone chemistry microparticles (SiMP) anode, in order to overcome its short life cycle defects. The results show that the low cost SiMP (~3-8 μm) can not be stable anodes made deep galvanostatic cycling before (less than 9 cycles), and self-healing using the polymer (SHPS) after coating the anode with excellent cycle life can be stably cyclic ring 90 and held 80% of the initial capacity. Cycle life are other reportsSiMP times the anode, and the capacity up to about 3,000 mA h g-1. Cycle cracks and damage may be repaired by coating randomly branched hydrogen bonding between polymer chains SHPs spontaneously. This new concept of self-healing electrode materials may also be subjected to other mechanical problems in an electrochemical reaction, a fuel cell, the electrode material and the catalytic decomposition of water.
References: Self-healing chemistry enables the stable operation of siliconmicroparticle anodes for high-energy lithium-ion batteries Nature Chem 5,1042-1048 (2013) DOI:.. 10.1038 / nchem.1802 link description: https://www.nature.com/articles/nchem.18023. Adv. Energy Mater .: binder assist the self-healing capacity of a high area silica microparticles anode
though self-repair of polymer (SHPS) can effectively mitigate the anode of silicon microparticles, but has yet to achieve a high quality Si load and long-term cycle stability. In response to these problems, Stanford University Professor Cui Yihuo Baozhe Nan propose a new electrode design, i.e., by distributing the SHP 3D Si particle layer, in order to shorten the diffusion path to promote faster healing response. Based on this design, silicon prepared anode area successfully achieved high-capacity low-cost Si microparticles (3-4 mAh cm-2) and more than 140 turns stable cycle life. Advantage of this design is that wherein:
i) a high capacity area, close to the actual needs of the battery;
- ii) a material based on low-cost metallurgical silicon powder;
- iii ) by using scalable precipitation – Si to select an appropriate size flotation process or a ball mill, to achieve optimum performance.
Reference hereinOffer:. High-Areal-CapacitySilicon Electrodes with Low-Cost Silicon ParticlesBased on Spatial Control of Self-Healing Binder Adv.Energy Mater, 5:. 1401826. DOI: 10.1002 / aenm.201401826 link description:
https: // onlinelibrary.wiley.com/doi/full/10.1002/aenm.2014018264. Adv. Mater .: elastomeric self-healing capacity of the polymer coating to achieve a high tensile graphitic carbon / silicon anodes
generally, the inorganic active electrode material is rigid and hard. The main way to achieve the stretchable electrode active material is made of a stretchable non-stretchable structure. Although there have been some successful examples, for example, pre-strained polydimethylsiloxane curved upper (PDMS) substrate Li4Ti5O12 / carbon nanotube films and carbon nanotube fibers a spring-like, but still no reports of high capacity stretchability electrode. In view of this, Stanford University Professor Cui Yihuo Baozhe Nan first demonstration of self-repair elastic polymer by a conformal coating of newly synthesized successfully achieved / silicone foam stretchable high capacity electrode graphitic carbon. Previously reported healing different supramolecular polymers, since such a material bond and covalently crosslinked sacrificial hydrogen bonding become more rigid, and has a large elastic strain range. Studies have shown that self-healing elastomer is uniformly coated on the 3D graphitic carbon / silicon foam, and to impart a high stretchability of the composite electrode (88%), and subjected to 1000 cycles at 25% stretch releasing under strain, and It will not increase the harmful resistance. Prepared graphitic carbon / Si composite electrode of the total capacity reaches 719 mAh g-1, is stretchable Li4Ti5O12 four times the anode material for lithium ion batteries are widely used, and maintained 81% of its charge after 100 cycles.
Reference: A Stretchable Graphitic Carb.. On / Si Anode Enabled by Conformal Coatingof a Self-Healing Elastic Polymer Adv Mater, 28:. 2455-2461 DOI:. 10.1002 / adma.201504723 description link:. https://onlinelibrary.wiley.com/ doi / full / 10.1002 / adma.201504723 5. Adv. Energy Mater .: repairing high ionic conductivity from the anode binders for high-performance silicon particles
charging and discharging process, silicon anode accompanied by huge volume change (300% to 400%), resulting in structural collapse of the electrode active material and peeling, thereby enabling the electrode to lose contact with electrically active, while the unstable electrode / electrolyte interface will aggravate side reaction between the electrolyte and electrode happened. For this problem, Professor Professor Cui Yihe Bao Zhenan Stanford University (co-author) team designed a new type of polymer binder, electrode materials to achieve a high capacity, excellent cycle and rate capability. Researchers polyethylene glycol (PEG) groups into the polymer self-repairing material (SHP) to obtain a new polymer (SHP-PEG), and the negative electrode used as a binder micron silicon. The SHP-PEG adhesive SHP Li ion conductivity and self-healing ability of PEG combine to make the interface between the silicon particles and the electrolyte microns effectively improved. Thanks to the binder and the self-healing high ionic conductivity, the silicon particles can maintain electrical conductivity after multiple cycles, while the side reactions between the electrode and the electrolyte has been effectively suppressed. In addition, high capacity Li ion charge transfer between the silicon particles and the electrolyte, the electrode material exhibits an excellent rate properties.
Reference: Ionically Conductive Self-Healing Binder for Low Cost Si Microparticles Anodes in Li-Ion Batteries.Adv.Energy Mater, 2018, DOI:. 10.1002 / aenm.201703138 link description: https://onlinelibrary.wiley.com/doi/full/10.1002/aenm.201703138 Part 4. Li sulfur battery
1 Joule:. based redox mediator quinone promote Li2S oxide Li-S battery
in a lithium-sulfur (Li-S) battery, the sulfur and lithium sulfide ( Li 2 S) insulating cause large polarization and low utilization of sulfur, lead and soluble polysulfide shuttle inside the loop. In addition, dissolution – precipitation route redox reactions passivating oxide reduction reaction of the active interface and damage the electrode structures thereby affecting cell performance. In view of this, Stanford University professor Yi Cui and team of Prof. Baozhe Nan introduced quinone derivative as a redox mediator (RM) to the electrolyte, to promote oxidation of Li2S. At the same time, by adjusting the specific nature of the quinone derivative: redox potential, solubility, and electrochemical stability, can improve battery performance. The study found that a quinone-based RM can effectively prevent dead Li2S deposition, thereby reducing the polarization cycle life. Quinone-based customized Li2S electrode assembly RM initial charging potential of 2.5V at 0.5C or less, and a discharge capacity up to 1300 mAh g-1.
Reference: Designing a Quinone-Based Redox Mediator to Facilitate Li2SOxidation in Li-S Batteries Joule 2019, 3, 872-884 DOI:.. 10.1016 / j.joule.2018.12.018 link description: https: //www.sciencedirect.com/science/article/pii/S254243511830624X. 2 ACS Nano: a conductive polymer PEDOT: PSS coating improves the performance of Li-S cell
Rechargeable lithium sulfur (Li-S) cell has a high theoretical specific energy, low material costs and environmental safety, thus showing great potential in the next generation of high-performance energy storage system. One of the main obstacles to its commercialization due to uncontrolled polysulfide dissolution and re-deposition due to rapid capacity fading. Since the porous carbon matrix may be trapped polysulfide, porous carbon structures have been used to improve the performance of Li-S battery. However, if no effective coating coated carbon / sulfur particles, the diffusion time will polysulfide. In view of this, Stanford University professor Yi Cui and team by Professor Baozhe Nan conductive poly (3,4-ethylene dioxythiophene) – poly (styrenesulfonate) (PEDOT: PSS) is applied to the mesoporous carbon / sulfur particles on reaching the diffusion holes therethrough so that polysulfide carbon matrix minimized purposes. After the surface coating, the sulfur electrode coulombic efficiency increased from 93% to 97%, reduced capacity fade from 40% / 15% to 100 cycles / 100 cycles. Further, the discharge capacity of the polymer coating higher than about 10% of the exposed coating at C / 5 rate initial discharge capacity was 1140mAh g-1, through a stable discharge capacity after 150 cycle overrun of 600 mAh g-1.
Reference: Improving the Performance of Lithium-Sulfur Batteries by ConductivePolymer Coating.ACS Nano 2011, 5, 11, 9187-9193 DOI:.. 10.1021 / nn203436j link description: https: //pubs.acs. org / doi / abs / 10.1021 / nn203436j 3. ACS EnergyLett .: efficiently bonded pyridine functionalized polymers enhance the stability of the sulfur electrode
because of its high conductivity porous carbon and high surface area, has been previously widely used as a sulfur (S) of the material of the electrode body. However, theyOften they lack a strong chemical affinity to stabilize the polysulfide. Although use of conductive polymers to stabilize the S electrodes, conductive polymers previously used is generally insoluble, it is a challenge from the solution is uniformly applied to the non-polar carbon substrate. In view of this, Professor Professor Cui Yihe Bao Zhenan team at Stanford University has developed a new part of the conjugated polymer design strategies for stable high sulfur content and sulfur electrode. This strategy takes advantage (1) pyridyl order to create a strong Li2Sx bond, which has been confirmed by XPS and simulation, (2) providing a conductive polythiophene-based conjugated skeleton (3) reasonable incorporated polarity in the main chain section, to provide a porous structure and good solubility. Interestingly, compared to the side-chain functional polymer P30-S (81%), the polymer main chain of the modified P30-B has a higher cycle retention ratio after 100 cycles (90%). Importantly, the new design strategy provides key features needed to achieve improved mixing sulfide electrode, the battery performance at a high sulfur content of up to 90% after 300-cycle capacity retention rate was 80%, which is the other polymer sulfur cathode system design can not be achieved.
Reference: Enhanced Cycling Stability of Sulfur Electrodes through EffectiveBinding of Pyridine-Functionalized Polymer ACS Energy Lett 2017, 2, 10,2454-2462 DOI:… 10.1021 / acsenergylett.7b00772 link description: https: / sodium ion battery /pubs.acs.org/doi/abs/10.1021/acsenergylett.7b00772Part 5.
1 Nature Energy:. The organic high-capacity battery reversible sodium
[123 ] Because of having a high theoretical specific capacity of 501 mAh g-1 and abundant, sodium rose brown (Na2C6O6) sodium ion battery is the most promisingOne of the cathode. However, compared with the theoretical value, reported brownish rose sodium reversible capacity is very low, and the constraints are not clear. In view of this, Bao Zhenan professor at Stanford University and Professor Cui Yi (co-author) to explore and reveal the reasons Na2C6O6 reversible cycling capacity limited. Studies have shown that, Na2C6O6 occur irreversible phase transition between the α-Na2C6O6 γ- Na2C6O6 during charge and discharge, which is the origin Na2C6O6 redox active decrease. To solve this problem, by reducing the grain size of Na2C6O6 and select the appropriate method of the electrolyte solution is reduced activation energy barrier of the phase change, so that phase change during charge and discharge between the α-N Na2C6O6 and γ- Na2C6O6 includes highly reversible characteristics, to achieve the sodium storage mechanism in each unit cell Na2C6O6 sodium atoms reversibly store 4, thereby achieving the high reversible capacity and cycle stability. Electrochemical tests showed that, when selecting a strong solvation diglyme (DEGDME) is used as an electrolyte solution, the positive electrode nano Na2C6O6 reach 484 mAh / g of reversible capacity and 726 Wh / kg energy density (based on the positive electrode Na2C6O6 ), up to 87% energy efficiency, and has high capacity retention ratio. The positive electrode Na2C6O6 than 96.6% of the theoretical energy value, and exceed all the sodium ion battery positive electrode material prior reported.
Reference: High-performance sodium-organic battery by realizing four-sodiumstorage in disodium rhodizonate Nat Energy 2, 861-868 (2017) DOI:…. 10.1038 / s41560-017-0014-y link description: [ .. 123] https://www.nature.com/articles/s41560-017-0014-y/
2 J. Am Chem two-dimensional conductive metal Soc .: -. organic framework six-diaminobenzene the storage stability for high power sodium redox-active organic material as an electrode of a rechargeable battery by increasing attention. However, the low electronic conductivity under redox conditions, and chemical and structural poor stability limits its application. In view of this, Stanford University professor Baozhe Nan Professor Yi Cui (co-author) reported a novel two-dimensional conductive cobalt-based metal-organic framework (MOF) Co-HAB, which is connected between the active group by a redox six aminobenzene the conjugated ligand, a stable, accessible, compact high-power energy storage device of the active site (the HAB) and co (II) centers. In view of the Co-HAB has excellent ability to stabilize the reaction of the HAB, demonstrated the first successful each of the three electron HAB reversible oxidation-reduction reaction, thereby providing a promising new electrode materials are sodium ion storage. Specifically, by synthesizing the adjustability of the Co-HAB realized 1.57 S cm-1 is of conductivity, thereby achieving a high rate capability, provides 214 mAh g-1 or 45 s 7 minutes providing the 152 mAh g-1. Meanwhile, when increasing the effective mass of the load to 9.6 mg cm-2, the area increases almost linearly capacity, only a trace of the conductive agent will reach 2.6 mAh cm-2. Reference: Stabilization of Hexaaminobenzene in a 2D Conductive Metal-OrganicFramework for High Power Sodium Storage J. Am Chem Soc 2018, 140, 32,10315-10323 DOI:….. 10.1021 / jacs.8b06020 description link:
Part 6. thermosensitive polymer switching material 1 Nature Energy:. rapid reversible thermal switch polymeric material, to prevent overheating of the lithium battery fire
next security problems have been hamperedBottlenecks scale generation of high energy density battery applications, particularly batteries caught fire due to overheating. To address this challenge, Professor Bao Zhenan \”Gemini\” and Stanford University professor Yi Cui work together reported a promising new technology, low cost, in order to prevent overheating of lithium batteries. They increased in the conventional lithium-ion battery of a thermosensitive polymer film \”switch\” materials, if the battery temperature in the battery circuit will rapidly \”cut off\”, so as to cool; once to normal temperature, the polymer film also returned to normal state, so that the battery back to work. The material electrochemically stable graphene coating spike mixed nickel nanoparticles, the nanoparticles are mixed in a polymer matrix having a high thermal expansion coefficients. Polymer composite film made up of a display 50 S cm-1 at room temperature conductivity is high. Importantly, the conductivity of the polymer composite film can be reduced in the order of seven to eight seconds in reaching a transition temperature, and spontaneous recovery at room temperature. This built-in battery may be self-regulating material is rapidly closed under an abnormal condition (e.g., overheating and short-circuit), and to resume its normal function, without affecting the performance or cause thermal runaway.
Reference: Fast and reversible thermoresponsive polymer switching materials forsafer batteries Nat Energy 1, 15009 (2016) DOI:.. 10.1038 / nenergy.2015.9 link description: