Low discharge capacity and poor cycle stability are the major obstacles hindering the operation of Li-O₂ batteries with high-energy-density. These obstacles are mainly caused by the cathode passivation behaviours and the accumulation of by-products. Promoting the discharge process in solution and accelerating the decomposition of discharge products and by-products are able to alleviate above problems to some extent. Herein, chiral salen-Co(II) complex, (1R,2R)-(-)-N,N-bis(3,5-di-t-butylsalicylidene)-1,2-cyclohexanediaminocobalt(II) (Co(II)) as a multi-functional redox mediator was introduced into electrolyte to induce solution phase formation of Li₂O₂ and catalyze the oxidation of Li₂O₂ and main by-products Li₂CO₃. Due to the Co(II) has the solvation effect towards Li⁺, it can drive solution phase formation of Li₂O₂, to prevent electrode from passivation and then increase the discharge capacity with a high Li₂O₂ yield of 96.09 %. Furthermore, the Co(II) possesses suitable redox couple potentials, and it does so while simultaneously boosting the oxidization of Li₂O₂ and the decomposition of Li₂CO₃, reducing charge overpotential, and promoting cycle lifespan. Thereby, a cell with Co(II) achieved a long cycling stability at low charge plateau (3.66 V) over 252 cycles with a specific capacity of 500 mAh·g_carbon⁻¹.

Rationally designing sulfur hosts with the functions of confining lithium polysulfides (LiPSs) and promoting sulfur reaction kinetics is critically important to the real implementation of lithium-sulfur (Li-S) batteries. Herein, the defect-rich carbon black (CB) as sulfur host was successfully constructed through a rationally regulated defect engineering. Thus-obtained defect-rich CB can act as an active electrocatalyst to enable the sulfur redox reaction kinetics, which could be regarded as effective inhibitor to alleviate the LiPS shuttle. As expected, the cathode consisting of sulfur and defect-rich CB presents a high rate capacity of 783.8 mA·h·g^-1 at 4 C and a low capacity decay of only 0.07% per cycle at 2 C over 500 cycles, showing favorable electrochemical performances. The strategy in this investigation paves a promising way to the design of active electrocatalysts for realizing commercially viable Li-S batteries.

There have been few reports concerning the hydrothermal synthesis of silicon anode materials. In this manuscript, starting from the very cheap silica sol, we hydrothermally prepared porous silicon nanospheres in an autoclave at 180 ℃. As anode materials for lithium-ion batteries (LIBs), the as-prepared nano-silicon anode without any carbon coating delivers a high reversible specific capacity of 2, 650 mAh·g^-1 at 0.36 A·g^-1 and a significant cycling stability of about 950 mAh·g^-1 at 3.6 A·g^-1 during 500 cycles.