High-performance
lithium-ion batteries (LIBs) demand efficient
and selective transport of lithium ions. Inspired by ion channels
in biology systems, lithium-ion channels are constructed by chemically
modifying the nanoporous channels of metal–organic frameworks
(MOFs) with negatively charged sulfonate groups. Analogous to the
biological ion channels, such pendant anionic moieties repel free
anions while allowing efficient transport of cations through the pore
channels. Implementing such MOFs as an electrolyte membrane doubly
enhances the lithium-ion transference number, alleviates concentration
polarization, and affords striking durability of high-rate LIBs. This
work demonstrates an ion-selective material design that effectively
tunes the ion-transport behavior and could assist with more efficient
operation of LIBs.
A new family of solid-like electrolytes was developed by infiltrating MIL-100(Al), an electrochemically stable metal−organic-framework (MOF) material, with liquid electrolytes that contain cations from the 3rd period (Na + , Mg 2+ , and Al 3+ ) and the 1st group (Li + , Na + , K + , and Cs + ). The anions were immobilized within the MOF scaffolds upon complexing with the open metal sites, allowing effective transport of the cations in the nanoporous channels with high conductivity (up to 1 mS cm −1 ) and low activation energy (down to 0.2 eV). This general approach enables the fabrication of superior conductive solid-like electrolytes beyond lithium ions.
The development of lithium metal anodes capable of sustaining large volume changes, avoiding lithium dendrite formation, and remaining stable in ambient air is crucial for commercially viable lithium metal batteries. Toward this goal, the fabrication of porous and lithiophilic copper scaffolds via a powder metallurgy strategy is reported. Infiltrating the scaffolds with molten lithium followed by exposure to Freon R134a produces lithium metal anodes with dramatically improved rate performance and cycling stability. This work provides a simple yet effective route for the fabrication of safe, low‐cost lithium metal batteries with high energy density.
Silicon
is one of the most promising anode materials for lithium-ion
batteries due to its high theoretical capacity and low cost. However,
significant capacity fading caused by severe structural degradation
during cycling limits its practical implication. To overcome this
barrier, we design a covalently bonded nanocomposite of silicon and
poly(vinyl alcohol) (Si–PVA) by high-energy ball-milling of
a mixture of micron-sized Si and PVA. The obtained Si nanoparticles
are wrapped by resilient PVA coatings that covalently bond to the
Si particles. In such nanostructures, the soft PVA coatings can accommodate
the volume change of the Si particles during repeated lithiation and
delithiation. Simultaneously, as formed covalent bonds enhance the
mechanical strength of the coatings. Due to the significantly improved
structural stability, the Si–PVA composite delivers a lifespan
of 100 cycles with a high capacity of 1526 mAh g–1. In addition, a high initial Coulombic efficiency of over 86% and
an average value of 99.2% in subsequent cycles can be achieved. This
reactive ball-milling strategy provides a low-cost and scalable route
to fabricate high-performance anode materials.
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