Aqueous rechargeable zinc ion batteries have received widespread attention due to their high energy density and low cost. However, zinc metal anodes face fatal dendrite growth and detrimental side reactions, which affect the cycle stability and practical application of zinc ion batteries. Here, an in-situ formed hierarchical solid-electrolyte interphase composed of InF₃, In, and ZnF₂ layers with outside-in orientation on the Zn anode (denoted as Zn@InF₃) is developed by a sample InF₃ coating. The inner ultrathin ZnF₂ interface between Zn anode and InF₃ layer formed by the spontaneous galvanic replacement reaction between InF₃ and Zn, is conductive to achieving uniform Zn deposition and inhibits the growth of Zinc dendrites due to the high electrical resistivity and Zn²⁺ conductivity. Meanwhile, the middle uniformly generated metallic In and outside InF₃ layers functioning as corrosion inhibitor suppressing the side reaction due to the waterproof surfaces, good chemical inactivity, and high hydrogen evolution overpotential. Besides, the as-prepared zinc anode enables dendrite-free Zn plating/stripping for more than 6,000 h at nearly 100% coulombic efficiency (CE). Furthermore, coupled with the MnO₂ cathode, the full battery exhibits the long cycle of up to 1,000 cycles with a low negative-to-positive electrode capacity (N/P) ratio of 2.8.

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.

Aqueous rechargeable sodium ion batteries (ARSIBs), with intrinsic safety, low cost, and greenness, are attracting more and more attentions for large scale energy storage application. However, the low energy density hampers their practical application. Here, a battery architecture designed by bipolar electrode with graphite/amorphous carbon film as current collector shows high energy density and excellent rate-capability. The bipolar electrode architecture is designed to not only improve energy density of practical battery by minimizing inactive ingredient, such as tabs and cases, but also guarantee high rate-capability through a short electron transport distance in the through-plane direction instead of in-plane direction for traditional cell architecture. As a proof of concept, a prototype pouch cell of 8 V based on six Na₂MnFe(CN)₆||NaTi₂(PO₄)₃ bipolar electrodes stacking using a “water-in-polymer” gel electrolyte is demonstrated to cycle up to 4,000 times, with a high energy density of 86 Wh·kg⁻¹ based on total mass of both cathode and anode. This result opens a new avenue to develop advance high-energy ARSIBs for grid-scale energy storage applications.

The low initial Coulombic efficiency (ICE) of SiO_x anode caused by the irreversible generation of Li_ySiO_z and Li₂O during lithiation process limits its application for high energy-density lithium-ion batteries. Herein, we report a molten-salt-induced thermochemical prelithiation strategy for regulating the electrochemically active Si/O ratio of SiO_x and thus enhancing ICE through thermal treatment of pre-synthesized LiNH₂-coated SiO_x in molten LiCl at 700 ℃. Bulk SiO_x micro-particle was transformed into pomegranate- like prelithiated micro-cluster composite (M-Li-SiO_x) with SiO_x core and outer nano-sized agglomerates consisting of Li₂Si₂O₅, SiO₂, and Si. Through the analysis of the reaction intermediates, molten-LiCl could initiate reactions and promote mass transfer by the continuous extraction of oxygen component from SiO_x particle inner in the form of inert Li₂Si₂O₅ and SiO₂ nanotubes to realize the prelithiation. The degree of prelithiation can be regulated by adjusting the coating amount of LiNH₂ layer, and the resulted M-Li- SiO_x displays a prominent improvement of ICE from 58.73% to 88.2%. The graphite/M-Li-SiO_x (8:2) composite electrode delivers a discharge capacity of 497.29 mAh·g⁻¹ with an ICE of 91.79%. By pairing graphite/M-Li-SiO_x anode and LiFePO₄ cathode in a full-cell, an enhancement of energy density of 37.25% is realized compared with the full-cell containing graphite/SiO_x anode. Furthermore, ex-situ X-ray photoelectron spectroscopy (XPS)/Raman/X-ray diffraction (XRD) and related electrochemical measurements reveal the SiO_x core and Si of M-Li-SiO_x participate in the lithiation, and pre-generated Li₂Si₂O₅ with Li⁺ diffusivity and pomegranate-like structure reduces the reaction resistance and interface impedance of the solid electrolyte interphase (SEI) film.

Herein, a two-dimensional (2D) interspace-confined synthetic strategy is developed for producing MoS₂-intercalated graphite (G-MoS₂) hetero-layers composite through sulfuring the pre-synthesized stage-1 MoCl₅-graphite intercalation compound (MoCl₅-GIC). The in situ grown MoS₂ nanosheets (3-7 layers) are evenly encapsulated in graphite layers with intimate interface thus forming layer-by-layer MoS₂-intercalated graphite composite. In this structure, the unique merits of MoS₂ and graphite components are integrated, such as high capacity contribution of MoS₂ and the flexibility of graphite layers. Besides, the tight interfacial interaction between hetero-layers optimizes the potential of conductive graphite layers as matrix for MoS₂. As a result, the G-MoS₂ exhibits a high reversible Li⁺ storage of 344 mAh·g⁻¹ even at 10 A·g⁻¹ and a capacity of 539.9 mAh·g⁻¹ after 1,500 cycles at 5 A·g⁻¹. As for potassium ion battery, G-MoS₂ delivers a reversible capacity of 377.0 mAh·g⁻¹ at 0.1 A·g⁻¹ and 141.2 mAh·g⁻¹ even at 2 A·g⁻¹. Detailed experiments and density functional theory calculation demonstrate the existence of hetero-layers enhances the diffusion rates of Li⁺ and K⁺. This graphite interspace-confined synthetic methodology would provide new ideas for preparing function-integrated materials in energy storage and conversion, catalysis or other fields.

Two-dimensional (2D) materials have attracted enormous attention due to their functional applications in energy storage. In this work, a low-temperature molten-salt chemical exfoliation methodology is developed for producing free-standing 2D mesoporous Si through deintercalation of CaSi₂ in excess molten AlCl₃ at 195 ℃. The average dimension of these sheets is 1.5 μm, and the thickness of a single sheet is approximately 10 nm. The as-prepared 2D Si has a Brunauer–Emmett–Teller surface area of 154 m²·g^-1 and an average pore size of 5.87 nm. With this unique structure, the 2D Si exhibits superior Li-storage performance, including a reversible capacity of 2, 974 mA·h·g^-1 at 0.2 C, reversible capacities of 2, 162, 1, 947, and 1, 527 mA·h·g^-1 at 0.8, 2, and 5 C after 200 cycles, and a capacity retention of 357 mA·h·g^-1 even at 30 C (90 A·g^-1).

High-capacity anode materials are highly desirable for sodium ion batteries. Here, a porous Sb/Sb₂O₃ nanocomposite is successfully synthesized by the mild oxidization of Sb nanocrystals in air. In the composite, Sb contributes good conductivity and Sb₂O₃ improves cycling stability, particularly within the voltage window of 0.02–1.5 V. It remains at a reversible capacity of 540 mAh·g^–1 after 180 cycles at 0.66 A·g^–1. Even at 10 A·g^–1, the reversible capacity is still preserved at 412 mAh·g^–1, equivalent to 71.6% of that at 0.066 A·g^–1. These results are much better than Sb nanocrystals with a similar size and structure. Expanding the voltage window to 0.02–2.5 V includes the conversion reaction between Sb₂O₃ and Sb into the discharge/charge profiles. This would induce a large volume change and high structure strain/stress, deteriorating the cycling stability. The identification of a proper voltage window for Sb/Sb₂O₃ paves the way for its development in sodium ion 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.