All-solid-state polymer electrolytes are promising for lithium batteries, but Li+ transport in these electrolytes relies on amorphous chain segment movement, leading to low Li+ mobility and poor mechanical strength. Here we propose a novel Li+ transport mechanism mediated by PEO3:LiBF4 nanocrystals (NCPB) with the aggregate (AGG) anionic structure, which enables a change from amorphous to crystalline phase dominated ion transport in all-solid-state PEO/LiBF4 electrolyte. Experiments and simulations reveal that the interaction between Li+ and F in NCPB with AGG anionic structure simultaneously restricts anion transport and reorients anions within the free volume of NCPB, resulting in a three-coordination intermediate to facilitate Li+ transport. The unique Li+ transport mechanism through NCPB makes the PEO/LiBF4 electrolyte with a high Li+ transference number (0.73) and remarkably increased mechanical strength (storage modulus >100 MPa) at 45 °C. As a result, the Li|LiFePO4 batteries with the ultrathin self-supported PEO/LiBF4 electrolyte (10 μm) exhibit significantly improved cycle life (97 % @ 468 cycles) compared to those with PEO/LiTFSI electrolyte (failed @ 68 cycles). This work demonstrates a novel ion transport mechanism for achieving selective and rapid Li+ transport.

Lithium-ion batteries (LIBs) with conventional carbonate-based electrolytes suffer from safety concerns in large-scale applications. Phosphates feature high flame retardancy but are incompatible with graphite anode due to their inability to form a passivated solid electrolyte interphase (SEI). Herein, we report a monofluorinated co-solvent, diethyl fluoridophosphate (DEFP), featuring a unique P−F bond that allows a trade-off between safety and electrochemical performance in LIBs. The P−F bond in DEFP weakens ion-dipole interactions with Li + ions, lowering the desolvation barrier, and simultaneously reduces the lowest unoccupied molecular orbital (LUMO) of DEFP, promoting the formation of a robust and inorganic-rich SEI. Additionally, DEFP exhibits improved thermal stability due to both robust SEI and the inherent flame-retardant properties of the P−F bond. Consequently, the optimized DEFP-based electrolyte exhibits improved cyclability and rate capacity in LiNi 0.8 Co 0.1 Mn 0.1 O 2 ||graphite full cells compared with triethyl phosphate-based electrolytes and commercial carbonate electrolytes. Even at a low E/C ratio of 3.45 g Ah −1 , the 1.16 Ah NCM811||Gr pouch cells achieve a high capacity retention of 94.2 % after 200 cycles. This work provides a promising approach to decouple phosphate safety and graphite compatibility, paving the way for safer and high-performance lithium-ion batteries.

Designing spinel nanocrystals (NCs) with tailored structural composition and cation distribution is crucial for superior catalytic performance but remarkably challenging due to their intricate nature. Here, an aggregation growth restricted hot-injection method is presented by meticulously investigating the fundamental nucleation and aggregation-driven growth kinetics governing spinel NC formation to address this challenge. Through controlled collision probability of nuclei during growth, this approach enables the synthesis of spinel NCs with unprecedented, single nanometer (1.2 nm). Single-nanometer CoMn2O4 spinel via this method exhibits a highly tailored structure with a maximized population of highly active octahedral Mn atoms, thereby optimizing oxygen intermediate adsorption during oxygen reduction reaction (ORR). Consequently, it exhibits a remarkable half-wave potential of 0.88 V in ORR and leads to a superior power density (170.9 mW cm-2) in zinc-air battery, outperforming commercial Pt/C and most reported spinel oxides, revealing a clear structure-property relationship. This structure design strategy is readily adaptable for the precise synthesis and engineering of various spinel structures, opening new avenues for developing advanced electrocatalysts and energy storage materials.

Oxygen reduction reaction (ORR) is the bottleneck of metal-air batteries and fuel cells. Strain regulation can change the geometry and adjust the surface charge distribution of catalysts, which is a powerful strategy to optimize the ORR activity. The introduction of controlled strain to the material is still difficult to achieve. Herein, we present a temperature-pressure-induced strategy to achieve the controlled lattice strain for metal coordination polymers. Through the systematic study of the strain effect on ORR performance, the relationship between geometric and electronic effects is further understood and confirmed. The strained Co-DABDT (DABDT=2,5-diaminobenzene-1,4-dithiol) with 2 % lattice compression exhibits a superior half-wave potential of 0.81 V. Theoretical analysis reveals that the lattice strain changes spin-charge densities around S atoms for Co-DABDT, and then regulates the hydrogen bond interaction with intermediates to promote the ORR catalytic process. This work helps to understand the catalytic mechanism from the atomic level.

The inferior oxidative stability of commercial carbonate electrolytes and overgrowth of the electrode-electrolyte interphase (EEI) have largely hindered the development of high-voltage lithium metal batteries. In this study, these challenges are addressed by designing Li+-solvent chelating solvation structures to inhibit solvent decomposition using cyano-alkyl-phosphate as a demonstration. Theoretical and experimental studies confirm that the -P═O and -C≡N groups within diethyl (2-cyanethyl) phosphonate exhibit a comparable ability to coordinate with Li+, facilitating the formation of seven-membered chelating structures. This unique solvation structure contributes to the formation of anion-derived inorganic-rich EEI with high stability and robustness, hindering the further decomposition of the electrolyte. Additionally, the cyano group has a strong complexation with the transition metal (TM) in the cathode to inhibit TM dissolution, thereby ensuring the structural stability of the cathode particle. Utilizing this special chelating structure, the designed electrolyte demonstrates favorable Li plating/stripping reversibility and promising oxidative stability in high-voltage batteries. Consequently, the LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode exhibits a high capacity retention (90%) after operating 300 cycles. Under harsh testing conditions, the 4.6 V Li||NCM811 pouch cell with a capacity of 1.4 Ah (∼295 Wh kg-1 based on the total mass of the cell) retains 70% capacity after 80 cycles. This work provides new insights into the correlation between the solvation structure and oxidative stability of electrolytes, contributing significantly to the advancement of high-voltage lithium metal batteries.

Spinel oxides, with the formula AB2O4 (A and B represent metal ions) perform superior electrocatalytic characteristic when A and B are transition metals like Co, Fe, Mn, etc. Abundant researches have been attached to the structure designments while methods are often energy-intensive and inefficient. Here, we devised a universal strategy to achieve rapid synthesis of nanocrystalline spinel materials with multiple components (Co3O4, Mn3O4, CoMn2O4 and CoFe2O4 are as examples), where phase formation is within 15 seconds. Under the Joule-heating shock, a crack-break process of microcosmic phase transformation is observed by in situ transmission electron microscopy. The half-wave potential values of Co3O4-JH, Mn3O4-JH, CoMn2O4-JH and CoFe2O4-JH in the electrocatalytic oxygen reduction reaction were 0.77, 0.78, 0.79 and 0.76, respectively. This suggests that the Joule heating is a fast and efficient method for the preparation of spinel oxide electrocatalysts.

Sulfurized polyacrylonitrile (SPAN) is recognized as a promising organic cathode for long-lifespan lithium metal batteries. Nevertheless, the irreversible cleavage/formation of multiple sulfur-sulfur (S−S) bonds of SPAN within conventional ether-based electrolytes results in loss of active S species, severe capacity fading and shuttle effects. Herein, we propose a new electrolyte based on dipropyl ether (PE) solvent for Li-SPAN batteries. Benefiting from the particular chain-coordination structure and weak dipole interactions with Li + and active species, the resulting electrolyte not only achieves low desolvation energy barrier and high Li + transference number, but also displays stable electrolyte-electrode interface (EEI). Consequently, the full cells utilizing this electrolyte exhibit good cyclability, outstanding capacity retention and superior extreme-temperature (−50 °C to 50 °C) performance. Furthermore, the Ah-scale pouch cell with lean electrolyte (2.5 g Ah −1 ) achieves record cycle stability with 96.5 % capacity retention after 75 cycles, which deliver an initial specific energy density of 150 Wh kg −1 (based on the weight of the entire cell). Impressively, this strategy demonstrates universality in a series of organic electrodes employing with PE-based electrolytes. This work highlights the strategy for modulating the dipole interaction at EEI for long-lifespan Li-organic batteries at extreme conditions.

Regulating the atomic arrangement and electron redistribution is beneficial for tuning catalytic oxygen reduction reaction (ORR) performance and deciphering the intrinsic mechanism. Herein, we modulate the charge density around Co centers by designing and synthesizing three Co coordination polymer catalysts, including Co-DABDT (DABDT = 2,5-diaminobenzene-1,4-dithiol, Co-N2S2), Co-BTT (BTT = 1,2,4,5-tetramercaptobenzene, Co-S-4), and Co-BTA (BTA = 1,2,4,5-benzenetetramine, Co-N-4), to explore the structure-activity relationship between the coordination environment and ORR performance. Because of the high electronegativity of S compared to N atoms, the charge density of Co increases in the order of Co-BTA -> Co-DABDT -> Co-BTT. Experimentally, Co-DABDT@CNTs with Co-N2S2 delivers a remarkable half-wave potential of 0.85 +/- 0.002 V, outperforming Co-N-4 and Co-S-4 and even Pt/C (0.84 +/- 0.003 V). Zinc-air batteries using Co-DABDT@CNTs as the air cathode catalyst also demonstrate excellent power density and stability. The systematic characterization and theoretical simulation reveal that the charge redistribution on Co and S sites of Co-N2S2 would both effectively optimize and stabilize the key intermediate (OOH*) with the assistance of hydrogen bonding interactions between intermediates and active S atoms (*OO-H center dot center dot center dot S). Interpreting the mechanism of ORR in the coordination sphere provides a feasible way to improve catalytic activity at an atomic level.

Two-dimensional (2D) conjugated metal-organic polymers (c-MOPs), an emerging family of 2D materials, have attracted widespread interest for application in electrocatalysis due to their flexibly tunable components, abundance of accessible active sites, and high conductivity. The key challenges facing the usage of 2D c-MOPs as electrocatalysts are the need for rational design and synthesis methods for coordination polymers as well as an in-depth understanding of structure-activity relationships. Herein, we summarize the design principles, synthesis methods, conductive mechanisms, and catalytic behaviors of 2D c-MOPs. The large d-pi conjugation network and strong pi-pi stacking are responsible for the high conductivity of 2D c-MOPs. The coordination environment and electronic configuration of metal centers are decisive factors affecting the catalytic properties of 2D c-MOPs. This review provides insights into the preparation of 2D conductive c-MOP materials via modulation and optimization of active sites to enable high performance in electrochemical energy conversion systems.

Main-group ( s - and p -block) metals are generally regarded as catalytically inactive due to the delocalized s / p -band. Herein, we successfully synthesized a p -block antimony single-atom catalyst (Sb SAC) with the Sb−N 4 configuration for efficient catalysis of the oxygen reduction reaction (ORR). The obtained Sb SAC exhibits superior ORR activity with a half-wave potential of 0.86 V and excellent stability, which outperforms most transition-metal (TM, d -block) based SACs and commercial Pt/C. In addition, it presents an excellent power density of 184.6 mW cm −2 and a high specific capacity (803.5 mAh g −1 ) in Zn–air battery. Both experiment and theoretical calculation manifest that the active catalytic sites are positively charged Sb−N 4 single-metal sites, which have closed d shells. Density of states (DOS) results unveil the p orbital of the atomically dispersed Sb cation in Sb SAC can easily interact with O 2 - p orbital to form hybrid states, facilitating the charge transfer and generating appropriate adsorption strength for oxygen intermediates, lowering the energy barrier and modulating the rate-determining step. This work sheds light on the atomic-level preparing p -block Sb metal catalyst for highly active ORR, and further provides valuable guidelines for the rational design of other main-group-metal SACs.