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• KMnO 4 was used to treat Li-rich layered oxides for the first time. • Reconstruct the surface lattice structure. • The electrochemical performance was enormous enhanced after treatment. • Improve the conductivity of Li+ and reduce the impedance. • Simple operation and high efficiency. Li-rich layered materials are facing the problems of low initial coulomb efficiency and poor rate performance, which seriously restrict its commercial development. Herein, we modified Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 by KMnO 4 to reconstruct the surface lattice and improve the Li+ conduction efficiency. The material acquired higher initial coulomb efficiency after treatment. Moreover, the initial specific capacity of the treated material was increased from 214.4 mAh g−1 to 262.7 mAh g−1 at 0.2 C with the voltage range from 2.0 V to 4.8 V, and 88% remained after 100 cycles. Even at 10 C, the specific capacity of 91.6 mAh g−1 can still be obtained, which is three times more than the pristine. The method of surface treatment with KMnO 4 provides a new idea for the commercial development of Li-rich layered materials in the future. [ABSTRACT FROM AUTHOR]

Silicon is one of the most promising candidates for anode materials of lithium-ion batteries, due to its high theoretical capacity and low working voltage, etc. Nonetheless, silicon has huge volume change during the lithiation/delithiation, resulting in poor cycle performance. Herein, novel double-shell-structured Si@Al 2 O 3 @C nanoparticles are prepared to obtain stable electrochemical performance. The improved performance can be attributed to novel double-shell structure, which greatly improves the conductivity of material, stabilizes solid-electrolyte interface (SEI) film, and releases the expansion stress of silicon. Si@Al 2 O 3 @C nanoparticles deliver a specific capacity of 1316.1 mAh g−1 at 1 A g−1 after 100 cycles, and the average discharge capacity of Si@Al 2 O 3 @C nanoparticles at 4 A g−1 still remains 781.6 mAh g−1. Additionally, the initial Coulombic efficiency (ICE) of material is as high as 82.9%. This work offers a significant method to further enhance the performance of lithium-ion batteries. [Display omitted] • For lithium-ion batteries, double-shell-structured Si@Al 2 O 3 @C anode is reported for the first time. • The double-shell structure can improve conductivity, stabilize SEI film, and release the expansion pressure of silicon. • Si@Al 2 O 3 @C nanoparticles show a high ICE of 82.9% and a reversible capacity of 1316.1 mAh g−1 at 1 A g−1 after 100 cycles. • Simple two-step synthesis. [ABSTRACT FROM AUTHOR]

• For lithium-ion batteries, phosphorus-doped phenol formaldehyde resin is used as carbon source for the first time. • The doping of phosphorus increases the active sites of the material, and improves the Li+ diffusion coefficient. • The Si@C/P anode possesses an excellent discharge capacity of 1873 mAh g−1 at 1 A g−1 after 100 cycles. • Simple and convenient synthesis method. [Display omitted] As one of the most promising electrode materials for lithium-ion batteries, silicon offers a high theoretical capacity, but it has been greatly limited by a volume expansion effect and the formation of unstable solid–electrolyte interface (SEI) film. Herein, Si@C/P nanoparticles with excellent electrochemical properties were prepared simply by sol-gel method and carbonization process. For lithium-ion batteries, phosphorus-doped phenol formaldehyde resin was used as carbon source for the first time, and phosphorus was successfully doped into carbon skeleton. The synergistic effect of carbon layer and phosphorus doping limits the volume expansion of silicon, and improves the diffusion rate of Li+. The Si@C/P anode exhibits a high initial Coulombic efficiency (ICE) of 84.4% and a specific capacity of 1873 mAh g−1 at 1 A g−1 after 100 cycles. The material shows a good rate performance, the average specific capacity reaches 1422.3 mAh g−1 even at a high current density of 4 A g−1, demonstrating a bright perspective. [ABSTRACT FROM AUTHOR]