High-capacity electrodes based on multiple reaction mechanisms are promising for lithium storage, but the inferior conversion reversibility limits the practical application. Herein, the Cu-Sn-S (CTS) electrodes based on conversion-alloying mechanisms are synthesized with abundant Cu₄SnS₄ (75.98%) and beneficial Cu_7.2S₄ phases. The regulated composition and core-shell nanostructures can effectively mitigate the volume change and improve the lithiation performance of CTS upon cycling. Moreover, the composition evolution of CTS is comprehensively tracked via various in-situ tests, revealing that the abundant Cu₄SnS₄ and the formed Cu₃Sn after lithiation are the key factors to induce uniform phase distribution and enhanced conversion reversibility, which is confirmed by theoretical calculations. This work sheds light on the reaction process of electrodes based on multiple lithiation mechanisms, which could inspire the development of analogous energy materials.

The energy density of thin-film lithium batteries (TFLBs) is predominantly determined by the average voltage and specific capacity, however, the mechanism of regulating the voltage plateaus of the film electrodes is not well understood. In this study, three boride films (Co–B, Fe–B, and Co–Fe–B alloys) with different thicknesses were fabricated to enhance the specific capacity and voltage stability of TFLBs. By analyzing the cycling performance, redox peak evolution, and capacitive contribution, the thickness-dependent lithiation behavior of the thin/thick films was elucidated. Theoretical simulations and electrochemical analysis were conducted to investigate how the lithiation behaviors affected the voltage profiles of the film electrodes. In addition, the various-thickness CoB films were compared in all-solid-state TFLBs, demonstrating the universality and practicability of this simple regulation strategy to develop high-performance energy storage devices.

Magnesium-lithium hybrid batteries (MLHBs) have gained increasing attention due to their combined advantages of rapid ion insertion/extraction cathode and magnesium metal anode. Herein, SnS₂-SPAN hybrid cathode with strong C-Sn bond and rich defects is ingeniously constructed to realize Mg²⁺/Li⁺ co-intercalation. The physical and chemical double-confinement synergistic engineering of sulfurized polyacrylonitrile can suppress the agglomeration of SnS₂ nanoparticles and the volume expansion, simultaneously promote charge transfer and enhance structural stability. The introduced abundant sulfur vacancies provide more active sites for Mg²⁺/Li⁺ co-intercalation. Meanwhile, the beneficial effects of rich sulfur defects and C-Sn bond on enhanced electrochemical properties are further evidenced by density-functional theory (DFT) calculations. Therefore, compared with pristine SnS₂, SnS₂-SPAN cathode displays high specific capacity (218 mAh g⁻¹ at 0.5 A g⁻¹ over 700 cycles) and ultra-long cycling life (101 mAh g⁻¹ at 5 A g⁻¹ up to 28,000 cycles). And a high energy density of 307 Wh kg⁻¹ can be realized by the SnS₂-SPAN//Mg pouch cell. Such elaborate and simple design supplies a reference for the exploitation of advanced cathode materials with excellent electrochemical properties for MLHBs.

All-solid-state thin-film lithium batteries (TFLBs) are the ideal wireless power sources for on-chip micro/nanodevices due to the significant advantages of safety, portability, and integration. As the bottleneck for increasing the energy density of TFLBs, the key components of cathode, electrolyte, and anode are still underway to be improved. In this review, a brief history of TFLBs is first outlined by presenting several TFLB configurations. Based on the state-of-the-art materials developed for lithium-ion batteries (LIBs), the challenges and related strategies for the application of those potential electrode and electrolyte materials in TFLBs are discussed. Given the advanced manufacture and characterization techniques, the recent advances of TFLBs are reviewed for pursuing the high-energy-density and long-term-durability demands, which could guide the development of future TFLBs and analogous all-solid-state lithium batteries.