Recently, three-dimensional (3D) conductive frameworks have been chosen as the host for composite lithium (Li) metal anode because of their exceptional electrical conductivity and remarkable thermal and electrochemical stability. However, Li tends to accumulate on the top of the 3D frameworks with homogenous lithiophilicity and Li dendrite still growth. This work firstly designed a bimetallic metal-organic framework (MOF) (CuMn-MOF) derived Cu₂O and Mn₃O₄ nanoparticles decorated carbon cloth (CC) substrates (CC@Cu₂O/Mn₃O₄) to fabricate a composite Li anode. Thanks to the synergistic effects of lithiophilic Cu₂O and Mn₃O₄, the CC@Cu₂O/Mn₃O₄@Li symmetrical cell can afford a prolonged cycling lifespan (1400 h) under an ultrahigh current density and areal capacity (6 mA·cm⁻²/6 mAh·cm⁻²). When coupled with the LiFePO₄ (LFP) cathode, the LFP||CC@Cu₂O/Mn₃O₄@Li full cell demonstrated a superior performance of 89.7 mAh·g⁻¹ even at an extremely high current density (10 C). Furthermore, it can also be matched well with LiNi_0.5Co_0.2Mn_0.3O₂ (NCM523) cathode. Importantly, to explain the excellent performances of the CC@Cu₂O/Mn₃O₄@Li composite anode, an intermittent model was also proposed. This study offers a novel model that can enhance our comprehension of the Li deposition behavior and pave the way to attain stable and safe Li metal anodes by employing bimetallic MOF-derived materials to construct 3D frameworks.

Sulfide electrolyte-based all-solid-state batteries (ASSBs) are potential next generation energy storage technology due to the high ionic conductivity of sulfide electrolytes and potentially improved energy density and safety. However, the performance of ASSBs at/below subzero temperatures has not been explored systematically. Herein, low temperature (LT) performance of LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811)|Li_9.54Si_1.74P_1.44S_11.7Cl_0.3 (LiSPSCl)|Li₄Ti₅O₁₂ (LTO) ASSBs was investigated. By charging the ASSB to 6 V at −40 °C, a capacity of 100.7 mAh∙g⁻¹ at 20 mA∙g⁻¹ was achieved, which is much higher than that charged to 4.3 V (4.6 mAh∙g⁻¹) at −40 °C. Moreover, atomic resolution microscopy revealed that the NCM811 remained almost intact even after being charged to 6 V. In contrast, NCM811 was entirely destructed when charged to 6 V at room temperature. The sharp difference arises from the large internal charge transfer resistance at LT which requires high voltage to overcome. Nevertheless, such high voltage is not harmful to the active material but beneficial to extracting most energy out of the ASSBs at LT. We also demonstrated that thinner electrolyte is favorable for LT operation of ASSBs due to the reduced ion transfer distance. This work provides new strategies to boost the capacity and energy density of sulfide-based ASSBs at LT for dedicated LT applications.

Sodium (Na) metal batteries (SMBs) using Na anode are potential “beyond lithium” electrochemical technology for future energy storage applications. However, uncontrollable Na dendrite growth has plagued the application of SMBs. Understanding Na deposition mechanisms, particularly the early stage of Na deposition kinetics, is critical to enable the SMBs. In this context, we conducted in situ observations of the early stage of electrochemical Na deposition. We revealed an important electrochemical Ostwald ripening (EOR) phenomenon which dictated the early stage of Na deposition. Namely, small Na nanocrystals were nucleated randomly, which then grew. During growth, smaller Na nanocrystals were contained by bigger ones via EOR. We observed two types of EOR with one involving only electrochemical reaction driven by electrochemical potential difference between bigger and smaller nanocrystals; while the other being dominated by mass transport governed by surface energy minimization. The results provide new understanding to the Na deposition mechanism, which may be useful for the development of SMB for energy storage applications.