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In this paper, we employ lithium-conducting covalent-organic-framework (COF) as the coating layer for silicon (Si) nanoparticles, which serve as artificial solid electrolyte interphase (SEI) for Si electrode. Here, the COF coating layer reduces the electrolyte decomposition, thus the coulombic efficiency (CE) and cycling stability of the Si electrodes are dramatically improved. Additionally, the superior lithium–ion conductivity of COF can enhance the lithium-ion transportation kinetics of Si electrode. COF coated Si presented a high specific capacity of 1864 mAh g^–1 at a high current density of 2000 mA g^–1 and high capacity retention of more than 60% after 1000 cycles.

With high specific capacity, the layered Li-rich Mn-based oxide (LRMO) is a promising candidate cathode material for Li-ion batteries. However, the irreversible release of Li-ions during the first charging process, instability of LRMO/electrolyte interface and relatively low ion conductivity of LRMO result in low initial Coulombic efficiency (ICE), poor cycle stability and rate performance, which prohibit its further application. Furthermore, interface engineering via additive coating is expected to effectively address these issues. Herein, we rely on potassium Prussian blue (KPB), a Li⁺ acceptor with good ion conductivity, as a new coating material on LRMO particles. The KPB coating not onlymore » forms a protective layer on the surface of LRMO against electrolyte corrosion, but also functions as a host for Li⁺ transport and accommodation, leading to enhanced ion conductivity and ICE of LRMO cathode. Consequently, 2 wt% KPB coated LRMO cathode achieved an initial discharge capacity of up to 281.7 mA h g^-1 with an ICE of 85.69% compared to an ICE of 79.52% for the LRMO cathode without coating. The cycling and rate performance are also greatly improved as evidenced by the well maintained capacity of up to 176.8 mA h g^-1 after 100 cycles at a current density of 0.5 C, compared to the limited capacity of only 135.3 mA h g^-1 for the LRMO cathode without coating. Overall, this work pioneers the use of potassium Prussian blue as additive coating material to enhance performance of LRMO cathode, and we expect it to inspire the battery community with new strategies of material engineering/design toward practical application in high-energy lithium-ion batteries.« less