Employing quasi-solid-state gel polymer electrolyte (GPE) instead of the liquid counterpart has been regarded as a promising strategy for improving the electrochemical performance of Li metal batteries. However, the poor and uneven interfacial contact between Li metal anode and GPE could cause large interfacial resistance and electrochemical Li stripping/plating inhomogeneity, deteriorating the electrochemical performance. Herein, we proposed that the functional component of composite anode could work as the catalyst to promote the in situ polymerization reaction, and we experimentally realized the integration of polymerized-dioxolane electrolyte and Li/Li₂₂Sn₅/LiF composite electrode with low interfacial resistance and good stability by in situ catalyzation polymerization. Thus, the reaction kinetics and stability of metallic Li anode were significantly enhanced. As a demonstration, symmetric cell using such a GPE-Li/Li₂₂Sn₅/LiF integration achieved stable cycling beyond 250 cycles with small potential hysteresis of 25 mV at 1 mA·cm⁻² and 1 mAh·cm⁻², far outperforming the counterpart regular GPE on pure Li. Paired with LiNi_0.5Co_0.3Mn_0.2O₂, the full cell with the GPE-Li/Li₂₂Sn₅/LiF integration maintained 85.7% of the original capacity after 100 cycles at 0.5 C (1 C = 200 mA·g⁻¹). Our research provides a promising strategy for reducing the resistance between GPE and Li metal anode, and realizes Li metal batteries with enhance electrochemical performance.

Achievement of lithium (Li) metal anode with thin thickness (e.g., ≤ 30 µm) is highly desirable for rechargeable high energy density batteries. However, the fabrication and application of such thin Li metal foil electrode remain challenging due to the poor mechanical processibility and inferior electrochemical performance of metallic Li. Here, mechanico-chemical synthesis of robust ultrathin Li/Li₃P (LLP) composite foils (~ 15 µm) is demonstrated by employing repeated mechanical rolling/stacking operations using red P and metallic Li as raw materials. The in-situ formed Li⁺-conductive Li₃P nanoparticles in metallic Li matrix and their tight bonding strengthen the mechanical durability and enable the successful fabrication of free-standing ultrathin Li metal composite foil. Besides, it also reduces the electrochemical Li nucleation barrier and homogenizes Li plating/stripping behavior. When matching to high-voltage LiCoO₂, the full cell with a low negative/positive (N/P) capacity ratio of ~ 1.5 offers a high energy density of ~ 522 W·h·kg⁻¹ at 0.5 C based on the mass of cathode and anode. Taking into account its facile manufacturing, potentially low cost, and good electrochemical performance, we believe that such an ultrathin composite Li metal foil design with nanoparticle-dispersion-strengthened mechanism may boost the development of high energy density Li metal batteries.

High-capacity lithium-containing alloy anodes (e.g., Li_4.4Si, Li_4.4Sn, and Li₃P) enable lithium-free cathodes (e.g., Sulfur, V₂O₅, and FeF₃) to produce next-generation lithium-ion batteries (LIBs) with high energy density. Herein, we design a Li₃P/C nanocomposite with Li₃P ultrafine nanodomains embedded in micrometer-scale porous carbon particles. Benefiting from the unique micro/nanostructure of the Li₃P/C nanocomposite, electrons transfer rapidly through the conductive pathway provided by the porous carbon framework and the volume change between Li₃P and P is confined in the nanopores of the carbon, which avoids the collapse of the whole Li₃P/C composite particles. As expected, the as-achieved Li₃P/C nanocomposite provided a high available lithium-ion capacity of 791 mAh/g (calculated based on the mass of Li₃P/C) at 0.1 C during the initial delithiation process. Meanwhile, the Li₃P/C nanocomposite showed 75% of its 0.5 C capacity at 6 C and stable cycling stability.

Lithium-ion batteries are approaching their theoretical limit and can no longer keep up with the increasing demands of human society. Lithium-sulfur batteries, with a high theoretical specific energy, are promising candidates for next generation energy storage. However, the use of Li metal in Li-S batteries compromises both safety and performance, enabling dendrite formation and causing fast capacity degradation. Previous studies have probed alternative battery systems to replace the metallic Li in Li-S system, such as a Si/Li₂S couple, with limited success in performance. Recently, there is a focus on red P as a favorable anode material to host Li. Here, we establish a novel battery scheme by utilizing a P/C nanocomposite anode and pairing it with a Li₂S coated carbon nanofiber cathode. We find that red P anode can be compatible in ether-based electrolyte systems and can be successfully coupled to a Li₂S cathode. Our proof of concept full-cell displays remarkable specific capacity, rate and cycling performances. We expect our work will provide a useful alternative system and valuable insight in the quest for next generation energy storage devices.