Bacterial Cellulose Composite Solid Polymer Electrolyte With High Tensile Strength and Lithium Dendrite Inhibition for Long Life Battery

The development of metallic lithium anode is restrained by lithium dendrite growth during cycling.The solid polymer electrolyte with high mechanical strength and lithium ion conductivity could be applied to inhibit lithium dendrite growth.To prepare the high-performance solid polymer electrolyte,the environment-friendly and cheap bacterial cellulose(BC)is used as filler incorporating with PEO-based electrolyte owing to good mechanical properties and Li salts compatibility.PEO/Li TFSI/BC composite solid polymer electrolytes(CSPE)are prepared easily by aqueous mixing in water.The lithium ion transference number of PEO/Li TFSI/BC CSPE is 0.57,which is higher than PEO/Li TFSI solid polymer electrolyte(SPE)(0.409).The PEO/Li TFSI/BC CSPE exhibits larger tensile strength(4.43 MPa)than PEO/Li TFSI SPE(1.34 MPa).The electrochemical window of composite electrolyte is widened 1.43 V by adding BC.Density functional theory calculations indicate that flex of PEO chains around Li atoms is suppressed,suggesting the enhanced lithium ion conductivity.Frontier molecular orbitals results suggest that an unfavorable intermolecular charge transfer lead to achieve higher potential for BC composite electrolyte.All solid-state Li metal battery with PEO/Li TFSI/BC CSPE delivers longer cycle life for 600 cycles than PEO/Li TFSI SPE battery(50 cycles).Li symmetrical battery using PEO/Li TFSI/BC CSPE could be stable for 1160 h.

Nanocomposite: Keggin-type Co_(4)-polyoxometalate@cobaltporphyrin linked graphdiyne for hydrogen evolution in seawater

Polyoxometalate-based nanocomposites with electrocatalytic activity have been applied in hydrogen evolution reactions(HER).Seawater as the main water resource on the earth should be developed as the water electrolysis to prepare high-purity hydrogen.In this paper,we used two synthesis strategies to prepare the nanocomposite Co_(4)-POM@Co-PGDY(Co_(4)-POM:the Kegging-type microcrystals of K_(10)[Co_(4)(PW_(9)O_(3)4)2]and Co-PGDY:cobalt-porphyrin linked graphdiyne)with excellent activity for HER.Co-PGDY as the porous material is applied not only as the protection of microcrystals towards the metal ion in seawater but also as the co-electrocatalyst of Co_(4)-POM.Co_(4)-POM@Co-PGDY exhibits excellent HER performance in seawater electrolytes with low overpotential and high stability at high density.Moreover,we have observed a key H_(3)O+intermediate emergence on the surface of nanocomposite during hydrogen evolution process in seawater by Raman synchrotron radiation-based Fourier transform infrared(SR-FTIR).The results in this paper provide an effective strategy for preparing polyoxometalate-based electrocatalysts with high-performance toward hydrogen evolution reaction.

氧化石墨炔提升界面电荷传输及分离以构筑高效二元有机太阳能电池器件

通过界面工程调节载流子动力学是提高太阳能电池器件效率的关键方式.在本工作中,我们成功制备了具有大量官能团的高分散性氧化石墨炔(GDYO),并将其应用于优化空穴传输材料PEDOT:PSS的性质以制备有机太阳能电池器件.结果表明,GDYO与PEDOT:PSS之间的π–π相互作用有利于优化电荷转移通道,提高空穴传输层的电导率和载流子迁移率.此外,界面接触的改善有助于抑制电荷的复合,提高空穴传输层和活性层之间的电荷提取.同时,活性层的形貌得到有效改善,瞬态吸收测试结果证实这有利于载流子分离率的提升,进而提高器件性能.因此,通过对载流子动力学的系统性优化,二元有机太阳能电池的光电转换效率达到17.5%,认证效率达到17.2%.本工作结果表明功能化石墨炔在有机光电器件领域具有广阔的应用前景.