High-Performance Lithiated SiOx Anode Obtained by a Controllable and Efficient Prelithiation Strategy

Controlled Prelithiation of SnO2/C Nanocomposite Anodes for Building Full Lithium-Ion Batteries

SnO₂ is an attractive anodic material for advanced lithium-ion batteries (LIBs). However, its low electronic conductivity and large volume change in lithiation/delithiation lead to a poor rate/cycling performance. Moreover, the initial Coulombic efficiencies (CEs) of SnO₂ anodes are usually too low to build practical full LIBs. Herein, a two-step hydrothermal synthesis and pyrolysis method is used to prepare a SnO₂/C nanocomposite, in which aggregated SnO₂ nanosheets and a carbon network are well-interpenetrated with each other. The SnO₂/C nanocomposite exhibits a good rate/cycling performance in half-cell tests but still shows a low initial CE of 45%. To overcome this shortage and realize its application in a full-cell assembly, the SnO₂/C anode is controllably prelithiated by the lithium-biphenyl reagent and then coupled with a LiCoO₂ cathode. The resulting full LIB displays a high capacity of over 98 mAh g^-1_LCO in 300 cycles at 1 C rate.

A High-Performance Primary Nanosheet Heterojunction Cathode Composed of Na0.44 MnO2 Tunnels and Layered Na2 Mn3 O7 for Na-Ion Batteries

Owing to its large capacity and high average potential, the structure and reversible O-redox compensation mechanism of Na₂ Mn₃ O₇ have recently been analyzed. However, capacity fade and low coulombic efficiency over multiple cycles have also been found to be a problem, which result from oxygen evolution at high charge voltages. Herein, a Na_0.44 MnO₂ ⋅Na₂ Mn₃ O₇ heterojunction of primary nanosheets was prepared by a sol-gel-assisted high-temperature sintering method. In the nanodomain regions, the close contact of Na_0.44 MnO₂ not only supplies multidimensional channels to improve the rate performance of the composite, but also plays the role of pillars for enhancing the cycling stability and coulombic efficiency; this is accomplished by suppressing oxygen evolution, which is confirmed by high-resolution (HR)TEM, cyclic voltammetry, and charge/discharge curves. As the cathode of a Na-ion battery, at 200 mA g^-1 after 100 cycles, the Na_0.44 MnO₂ ⋅Na₂ Mn₃ O₇ heterojunction retains an 88 % capacity and the coulombic efficiency approaches 100 % during the cycles. At 1000 mA g^-1 , the Na_0.44 MnO₂ ⋅Na₂ Mn₃ O₇ heterojunction has a discharge capacity of 72 mAh g^-1 . In addition, the average potential is as high as 2.7 V in the range 1.5-4.6 V. The above good performances indicate that heterojunctions are an effective strategy for addressing oxygen evolution by disturbing the long-range order distribution of manganese vacancies in the Mn-O layer.

Fast and Controllable Prelithiation of Hard Carbon Anodes for Lithium-Ion Batteries

Hard carbon has been extensively investigated as anode materials for high-energy lithium-ion batteries owing to its high capacity, long cycle life, good rate capability, and low cost of production. However, it suffers from a large irreversible capacity and thus low initial coulombic efficiency (ICE), which hinders its commercial use. Here, we developed a fast and controllable prelithiation method based on a chemical reaction using a lithium-containing reagent (1 M lithium biphenylide dissolved in tetrahydrofuran). The prelithiation extent can be easily controlled by tuning the reaction time. An SEI layer is formed during chemical prelithiation, and the ICE of prelithiated hard carbon in half-cell format can be increased to ∼106% in 30 s. When matched with a LiNi_1/3Co_1/3Mn_1/3O₂ cathode, the full cell with the prelithiated hard carbon anode exhibits a much improved ICE (90.2 vs 75%) and cycling performance than those of the pristine full cell. This facile prelithiation method is proved to be a practical solution for the commercial application of hard carbon materials.

Direct regeneration of spent LiFePO4via a graphite prelithiation strategy

A new, low-cost and green regeneration method was developed to revive spent LiFePO₄-based batteries.