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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.

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The electronic structure at the Ni, Mn and O sites and their evolution upon the electrochemical lithiation of Li(1-x)Ni0.5Mn1.5O4 (LNMO) in a lithium ion battery has been explored using comprehensive X-ray absorption near edge structure spectroscopy (XANES) at the Ni and Mn L3,2- and O K-edges, with both surface-sensitive and bulk-sensitive detection. It has confirmed that Ni reduction from Ni(4+) to Ni(2+) plays the leading role in charge compensation when the lithiation voltage is above 4.5 V. Our study also unveils the participation of oxygen in the charge compensation. Furthermore, the enhanced difference in the electronic structures of the surface and bulk in electrochemically cycled samples, and the different surface electronic structures of the fully discharged LNMO and the pristine one, highlight the importance of electrochemical activation. These findings are critical for a better understanding of the electrochemical reaction of LNMO and the influence of structural modifications to the surface region upon its performance, and will assist further efforts to improve this high-voltage cathode material for its application in lithium ion batteries.

Designing hollow/porous structure is regarded as an effective approach to address the dramatic volumetric variation issue for Si-based anode materials in Li-ion batteries (LIBs). Pioneer studies mainly focused on acid/alkali etching to create hollow/porous structures, which are, however, highly corrosive and may lead to a complicated synthetic process. In this paper, a dual carbon conductive network-encapsulated hollow SiO x (DC-HSiO x ) is fabricated through a green route, where polyacrylic acid is adopted as an eco-friendly soft template. Low electrical resistance and integrated electrode structure can be maintained during cycles because of the dual carbon conductive networks distributed both on the surface of single particles formed by amorphous carbon and among particles constructed by reduced graphene oxide. Importantly, the hollow space is reserved within SiO x spheres to accommodate the huge volumetric variation and shorten the transport pathway of Li+ ions. As a result, the DC-HSiO x composite delivers a large reversible capacity of 1113 mA h g–1 at 0.1 A g–1, an excellent cycling performance up to 300 cycles with a capacity retention of 92.5% at 0.5 A g–1, and a good rate capability. Furthermore, the DC-HSiO x //LiNi0.8Co0.1Mn0.1O2 full cell exhibits high energy density (419 W h kg–1) and superior cycling performance. These results render an opportunity for the unique DC-HSiO x composite as a potential anode material for use in high-performance LIBs.

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