Two-dimensional quinoxaline based low bandgap conjugated polymers for bulk-heterojunction solar cells

Li, Shuang; Tao, Yuan; Tu, Guoli; Zhang, Jian; Li, Zhen

doi:10.1039/c5py01027f

Cited by 92 publications

(125 citation statements)

References 62 publications

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“…(Figure 3k,l), where Li whiskers growing in LiTFSI electrolyte are clearly visible on Cu surface within 15 min, and then keep growing, after 30 min, into the fibrous‐like dendrites, same result has been reported by Cui and co‐workers. [ 50 ] Similar phenomenon can be obtained from the in situ optical photographs of Li–Cu cells using LiFSI electrolyte (Figure S11, Supporting Information). Comparatively, no such dendrite can be found on Cu surface after polarizing the cell for 30 min in LiHFDF electrolyte.…”

Section: Resultssupporting

confidence: 75%

New Lithium Salt Forms Interphases Suppressing Both Li Dendrite and Polysulfide Shuttling

Xiao

Han

Zeng

et al. 2020

Advanced Energy Materials

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1675 mA h g −1 ), low-toxicity, high natural abundance of sulfur, as well as environmental friendliness. [1][2][3][4][5] However, two major challenges closely associated with the electrolytes prevented any immediate commercialization of LSB: 1) the incessant reaction between Li-metal and electrolytes, leading to the constant growth of Li dendrite and inactive Li [6][7][8] and 2) the dissolution of the intermediate polysulfides and their subsequent shuttling. [9][10] These irreversible and parasitic processes result in fast capacity degradation, persistent loss of active materials (both Li and S), severe self-discharge and even catastrophic safety hazard. [11][12] Aiming to resolve these parasitic reactions, significant efforts have been made to develop new electrolyte formulations, including electrolyte additives [13][14][15] solvents, [16][17] and Li salts, with structures of either unsaturation or fluorination that can contribute unique interphasial chemistries to protect Li-metal or suppress polysulfide dissolution and shuttling. [18][19] Among these components, new anionic compounds (counterions of Li + in the salts) are rather rare as compared with new molecular compounds (solvents and additives), mainly due to the much higher difficulty associated with their designing and synthesis. Hence, how anions contribute to interphases remains little understood, although a few successful examples of anionderived interphases, as represented by LiBOB and LiDFOB in nonaqueous and LiTFSI in aqueous electrolytes, suggests that the protections provided by such interphases often outperform their molecular counterparts. In particular, for the interphase protecting Li-metal anode, the anion-derived interphase seems to be more effective than those formed by solvents or additives. [20][21][22][23] One challenge presented for anion-derived interphases is their negatively charged nature, which discourages their presence in the inner-Helmholtz layer at anode surface. [24] In the case of water-in-salt electrolytes (WiSE), such "anode challenge" was partially offset by superconcentration, which compresses the anions into the inner-Helmholtz layer and forces an interphasial chemistry that is otherwise impossible in diluted aqueous electrolyte. The astonishing benefit brought by such anion-derived interphase is an electrochemical stability window of 3-4 V. [25][26] Superconcentration concept has also been applied on both Li-metal anode [27] and sulfur-cathode, [28] in the hope that the interphasial chemistries formed by the existing Lithium-sulfur batteries (LSBs) are considered promising candidates for the next-generation energy-storage systems due to their high theoretical capacity and prevalent abundance of sulfur. Their reversible operation, however, encounters challenges from both the anode, where dendritic and dead Li-metal form, and the cathode, where polysulfides dissolve and become parasitic shuttles. Both issues arise from the imperfection of interphases between electrolyte and electrode. Herein, a new lithium salt based on ...

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Section: Resultssupporting

confidence: 75%

New Lithium Salt Forms Interphases Suppressing Both Li Dendrite and Polysulfide Shuttling

Xiao

Han

Zeng

et al. 2020

Advanced Energy Materials

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“…However, the development of Li metal anodes lags far behind conventional cathodes because of the non‐ideal Li deposition. A favorable Li deposition at the anode/separator interface increases the risk of short circuits caused by the dendrite penetration through separator . Non‐ideal Li deposition induces irregular superficial layer of solid electrode interphase (SEI), which may repeatedly consume cyclable Li atoms during charge/discharge and lower the Coulombic efficiency (CE).…”

Section: Introductionmentioning

confidence: 99%

“…In the past decades, many strategies have been proposed to improve the electrochemical properties of Li metal anodes. New electrolyte composition is developed to form stable SEI on Li anodes; Solid‐state electrolyte is used to suppress the dendrite growth of Li metal; Various porous scaffolds are fabricated to confine Li growth or to decrease the average current density . These attempts have demonstrated significant progress in improving Li growth and suppressing dendrites.…”

Section: Introductionmentioning

confidence: 99%

Silicon Quantum Dots Induce Uniform Lithium Plating in a Sandwiched Metal Anode

Zhao

et al. 2020

ChemElectroChem

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Lithium (Li) metal anodes are demanded by high-energy Li batteries because Li has the highest capacity and low electrode potential. However, Li metal anodes usually show poor cyclability and unsafe deposition at anode/separator interfaces, which may increase the risk of short circuits. In this work, we fabricate a sandwiched structure of reduced graphene oxides (rGO) with silicon (Si) quantum dots (QDs) as the inducing agents between rGO layers. Because of the lithiophilicity of Si QDs, Li growth is favorably guided away from the unsafe anode/separator interface towards the interlayer positions, significantly improving the cyclability and safety of the Si-QDssandwiched rGO anode. The uniformly-distributed Si QDs and layered electrode structure can regulate Li plating/stripping to avoid the superficial Li growth and reduce the accumulation of solid electrolyte interphase. The growth-guiding strategy using the sandwiched structure provides a new approach to fabricating high energy Li-based battery anodes.

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“…In addition, the fresh lithium with high activity is easily attacked by organic electrolytes . The side reactions reduces the coulomb efficiency of the lithium metal and raises safety issues …”

Section: Introductionmentioning

confidence: 99%

Dendrite‐Free Lithium Anodes with a Metal Organic Framework‐Derived Cake‐like TiO₂ Coating on the Separator

Wang

Zhao

et al. 2020

ChemElectroChem

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Lithium metal, with a high theoretical capacity of 3860 mAh/g and a low electrochemical potential of À 3.040 V, is an attractive anode material. However, its application has been hampered by irregular lithium dendrite growth and low coulombic efficiency. To solve these problems, a facile air calcination strategy was used to prepare cake-like TiO 2 nanoparticles with rich pores, which were further coated on one side of the commercial Celgard separator. The nanoscale mesoporous channels on the surface of TiO 2 particles can effectively block the growth of lithium dendrites, leading to dense and uniform Li deposition with a high coulombic efficiency. Compared with the blank cell (50 cycles of normal operation), the Li j j Cu cell with modified separator can run 100 cycles at 2 mA/cm 2 with an average coulombic efficiency of 97.3 %. These results herald a new approach to dendrite-free lithium anodes by nanostructured ceramic coating on the separator.

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Two-dimensional quinoxaline based low bandgap conjugated polymers for bulk-heterojunction solar cells

Cited by 92 publications

References 62 publications

New Lithium Salt Forms Interphases Suppressing Both Li Dendrite and Polysulfide Shuttling

New Lithium Salt Forms Interphases Suppressing Both Li Dendrite and Polysulfide Shuttling

Silicon Quantum Dots Induce Uniform Lithium Plating in a Sandwiched Metal Anode

Dendrite‐Free Lithium Anodes with a Metal Organic Framework‐Derived Cake‐like TiO₂ Coating on the Separator

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Two-dimensional quinoxaline based low bandgap conjugated polymers for bulk-heterojunction solar cells

Cited by 92 publications

References 62 publications

New Lithium Salt Forms Interphases Suppressing Both Li Dendrite and Polysulfide Shuttling

New Lithium Salt Forms Interphases Suppressing Both Li Dendrite and Polysulfide Shuttling

Silicon Quantum Dots Induce Uniform Lithium Plating in a Sandwiched Metal Anode

Dendrite‐Free Lithium Anodes with a Metal Organic Framework‐Derived Cake‐like TiO2 Coating on the Separator

Contact Info

Product

Resources

About

Dendrite‐Free Lithium Anodes with a Metal Organic Framework‐Derived Cake‐like TiO₂ Coating on the Separator