The
construction of three-dimensional lithiophilic hosts is one
of the most effective approaches for achieving the uniform nucleation
and alleviating the volume changes of the Li metal. Unfortunately,
some lithiophilic materials suffer from severe mechanical degradation
resulting from the large volume expansion during lithiation, which
causes a heterogeneous Li deposition. Herein, a low-nucleation-barrier
Cu3Sn alloy layer on a carbon paper (Cu3Sn/CP)
is constructed by a facile co-electrodeposition method for the Li
anode framework. Density functional theory calculations show that
the Cu3Sn alloy has a higher binding energy (−2.31
eV) than pure Sn (−1.97 eV) due to the electron-deficient state
of Sn in the alloy phase, which enables the lithiophilic Sn to have
increased affinity for Li. Additionally, the uniformly distributed
Cu particles can evenly disperse the electric field on the surface
of the carbon fiber and act as a “metal barrier” to
inhibit the volume expansion of the Sn particles during lithiation,
thereby enhancing the electrochemical stability of the alloy modification
layer. As a result, the Cu3Sn/CP anode framework exhibits
an exceptionally low nucleation overpotential (∼10 mV), a high
and steady Coulombic efficiency (>98.5% for more than 200 cycles),
and a long lifespan up to 1150 h. The full cells with LiFePO4 as a cathode show favorable cycling performance at 1 C with a capacity
retention rate of 95.2%. The construction of the Cu3Sn
alloy layer in this work sheds light on the design of a high-stability
lithiophilic host for the dendrite-free Li metal anode.
In the past few decades, the preparation of cellulose nanofibers (CNF) has been restricting its application in industrialization. A fast and green preparation method is urgently needed to promote the industrialization process. In this paper, eco-carboxymethylation of cellulose was first used to enable the carboxymethylation of eucalyptus wood dissolving pulp (EWDP) and then we introduced a new idea of isopropanol alcohol (IPA) washing followed by drying to disintegrate chemical modified fibers into dried nanometersized cellulose powders. The cellulose powders were transferred into CNF with a width of 18 nm and length of several hundred nanometers after high-pressure homogenization. The powder form of cellulose provided more chances for fibrillation which resulted in low energy consumption and high yield of CNF. The obtained CNF were employed to prepare nanopaper and conductive nanopaper by vacuum filtration. The fabricated nanopaper exhibited a high optical transmittance of 92% with a maximum tensile stress of 107.5 MPa. However, the optical transmittance of conductive nanopaper slowly decreased to 68% when the square resistance reached 18 Ω/sq. This novel route for preparing CNF was low toxicity, environmentally friendly and solved the blocking of the high-pressure homogenization process. The fabricated transparent flexible conductive nanopaper with smooth surface, high transmittance, high strength and good conductivity has great potential in the field of optoelectronics.
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