Electrochemical properties of polydopamine coated Ti-Si alloy anodes for Li-ion batteries

Impact of Surface Chemistry of Silicon Nanoparticles on the Structural and Electrochemical Properties of Si/Ni3.4Sn4 Composite Anode for Li-Ion Batteries

Embedding silicon nanoparticles in an intermetallic matrix is a promising strategy to produce remarkable bulk anode materials for lithium-ion (Li-ion) batteries with low potential, high electrochemical capacity and good cycling stability. These composite materials can be synthetized at a large scale using mechanical milling. However, for Si-Ni₃Sn₄ composites, milling also induces a chemical reaction between the two components leading to the formation of free Sn and NiSi₂, which is detrimental to the performance of the electrode. To prevent this reaction, a modification of the surface chemistry of the silicon has been undertaken. Si nanoparticles coated with a surface layer of either carbon or oxide were used instead of pure silicon. The influence of the coating on the composition, (micro)structure and electrochemical properties of Si-Ni₃Sn₄ composites is studied and compared with that of pure Si. Si coating strongly reduces the reaction between Si and Ni₃Sn₄ during milling. Moreover, contrary to pure silicon, Si-coated composites have a plate-like morphology in which the surface-modified silicon particles are surrounded by a nanostructured, Ni₃Sn₄-based matrix leading to smooth potential profiles during electrochemical cycling. The chemical homogeneity of the matrix is more uniform for carbon-coated than for oxygen-coated silicon. As a consequence, different electrochemical behaviors are obtained depending on the surface chemistry, with better lithiation properties for the carbon-covered silicon able to deliver over 500 mAh/g for at least 400 cycles.

Polydopamine-wrapped, silicon nanoparticle-impregnated macroporous CNT particles: rational design of high-performance lithium-ion battery anodes

We report simple yet rationally designed, polydopamine-wrapped, silicon nanoparticle-impregnated macroporous CNT particles for high-capacity lithium-ion batteries.

Biomimetic Synthesis of Polydopamine Coated ZnFe2O4 Composites as Anode Materials for Lithium-Ion Batteries

Metal oxides as anode materials for lithium storage suffer from poor cycling stability due to their conversion mechanisms. Here, we report an efficient biomimetic method to fabricate a conformal coating of conductive polymer on ZnFe2O4 nanoparticles, which shows outstanding electrochemical performance as anode material for lithium storage. Polydopamine (PDA) film, a bionic ionic permeable film, was successfully coated on the surfaces of ZnFe2O4 particles by the self-polymerization of dopamine in the presence of an alkaline buffer solution. The thickness of PDA coating layer was tunable by controlling the reaction time, and the obtained ZnFe2O4/PDA sample with 8 nm coating layer exhibited an outstanding electrochemical performance in terms of cycling stability and rate capability. ZnFe2O4/PDA composites delivered an initial discharge capacity of 2079 mAh g-1 at 1 A g-1 and showed a minimum capacity decay after 150 cycles. Importantly, the coating layer improved the rate capability of composites compared to that of its counterpart, the bare ZnFe2O4 particle materials. The outstanding electrochemical performance was because of the buffering and protective effects of the PDA coating layer, which could be a general protection strategy for electrode materials in lithium-ion batteries.