No abstract

The altering of electronic states of metal oxides offers a promising opportunity to realize high‐efficiency surface catalysis, which play a key role in regulating polysulfides (PS) redox in lithium–sulfur (Li–S) batteries. However, little effort has been devoted to understanding the relationship between the electronic state of metal oxides and a catalyst's properties in Li–S cells. Herein, defect‐rich heterojunction electrocatalysts composed of ultrathin TiO2‐x nanosheets and carbon nanotubes (CNTs) for Li–S batteries are reported. Theoretical simulations indicate that oxygen vacancies and heterojunction can enhance electronic conductivity and chemical adsorption. Spectroscopy and electrochemical techniques further indicate that the rich surface vacancies in TiO2‐x nanosheets result in highly activated trapping sites for LiPS and lower energy barriers for fast Li ion mobility. Meanwhile, the redistribution of electrons at the heterojunction interfaces realizes accelerated surface electron exchange. Coupled with a polyacrylate terpolymer (LA132) binder, the CNT@TiO2‐x–S electrodes exhibit a long cycle life of more than 300 cycles at 1 C and a high area capacity of 5.4 mAh cm−2. This work offers a new perspective on understanding catalyst design in energy storage devices through band engineering.

The formation of dendrites on a zinc (Zn) metal anode has limited its practical applications on aqueous batteries. Herein, an artificial composite protective layer consisting of nanosized metal–organic frameworks (MOFs) to improve the poor wetting effect of aqueous electrolytes on the Zn anode is proposed to reconstruct the Zn/electrolyte interface. In this layer, hydrophilic MOF nanoparticles serve as interconnecting electrolyte reservoirs enabling nanolevel wetting effect as well as regulating an electrolyte flux on Zn anode. This zincophilic interface exhibits significantly reduced charge-transfer resistance. As a result, stable and dendrite-free Zn plating/stripping cycling performance is achieved for over 500 cycles. In addition, especially at higher C-rates, the coating layer significantly reduces the overpotentials in a Zn/MnO2 aqueous battery during cycling. The proposed principle and method in this work demonstrate an effective way to reconstruct a stable interface on metal anodes (e.g., Zn) where a conventional solid-electrolyte interface (SEI) cannot be formed.

The cycling performance of a silicon/carbon composite anode has been significantly enhanced by using acrylic adhesive and modified acrylic adhesive as binder to fabricate the electrodes for lithium ion batteries. The capacity retentions of Si/C composite electrodes bound by acrylic adhesive and modified acrylic adhesive are 79% and 90% after 50 cycles, respectively. These two binders are electrochemically stable in the organic electrolyte in the working window. They also show larger adhesion strength between the coating and the Cu current collector as well as smaller solvent absorption in the electrolyte solvent than polyvinylidene fluoride (PVDF). Furthermore, sodium carboxyl methyl cellulose (CMC) plays an important role on improving the properties of acrylic adhesive, which increases the adhesive strength of acrylic adhesive and improves the activation of the electrodes.