Search

Li 7 La 3 Zr 2 O 12 (LLZO) is a potential solid electrolyte for all-solid-state batteries owing to its high ionic conductivity and excellent stability. The self-consolidation strategy is an extremely simplified method for LLZO preparation compared to the conventional preparation methods using hot- or cold-pressing operations. Despite the absence of high-pressure assistance, the self-consolidated LLZO exhibits high density and enhanced microstructure. The self-densification mechanism of LLZO solid electrolytes is interesting and deserves further investigation. Herein, the effects of the sintering time and the inadvertently introduced Al on the self-consolidation process are systematically studied. Extending sintering time expels the sintering voids at the grain boundaries, thereby promoting grain growth. The Li atoms in the LLZO crystal structure are rearranged and adjusted to reach an optimal state. The LLZO achieves a highly dense morphology with a Li+ ion conductivity of 3.87 × 10−4 S cm−1 when the sintering time is 20 h. Notably, an Al 2 O 3 crucible, instead of a MgO crucible, under the same sintering conditions, contributes to the LLZO self-consolidation by generating an Al-containing solid solution. This work sheds light on the key role of the solid solutions in LLZO self-consolidation, thereby inspiring an alternative optimization method for the preparation of solid electrolytes. [Display omitted] • Al-containing solid solution is the key to LLZO self-consolidation. • The generation of solid solution may just arise from sintered container. • Dense LLZO is achieved by expelling sintering voids and promoting grain growth. • LLZO morphology is changed while LLZO crystal structure is optimized. [ABSTRACT FROM AUTHOR]

The lithium-ion battery (LIB) is considered an ideal next-generation energy storage device owing to its high safety, high energy density, and low cost. Calendar loss of LIBs is the most important element in the long-term degradation of batteries. However, the calendar life is difficult to measure precisely because of the uncertain and overlong storage years. Consequently, accurately predicting the calendar life of LIBs is a key but challenging issue. In this work, a calendar life prediction model is developed for commercial large-capacity LiFePO 4 |graphite LIBs based on the pseudo-two-dimensional (P2D) electrochemical model integrated with solid electrolyte interface (SEI) growth side reactions and an empirical degradation rate model for reliability research. The excellent agreement between the model and the experimental storage data over a wide range of temperatures (−40 °C ∼ 70 °C) and SOCs demonstrates the high-fidelity of the model. The established model is sufficiently generic to predict the storage aging of LIBs over a long period of years. On the basis of the verified model, the impact of graphite particle radius distribution on the calendar loss of Li-ion batteries throughout a broad temperature range is investigated. This modeling work contributes to an improved understanding of the calendar loss behavior of LIBs and provides valuable guidance for future battery design optimization. [Display omitted] • An electrochemical model combining SEI film growth side reactions is presented. • The model is able to predict the calendar aging of Li-ion batteries accurately. • Storage at high temperatures and at high SOCs can accelerate SEI film growth. • Increasing the graphite particle radius helps mitigate the calendar loss. [ABSTRACT FROM AUTHOR]

Garnet Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 (LLZTO) is a promising solid electrolyte for solid-state batteries (SSBs) owing to its high ionic conductivity and high chemical/electrochemical stability. However, the solid-to-solid interface between LLZTO electrolyte and Li anode restricts its application. In this work, an in-situ integration of LLZTO electrolyte with Li anode is proposed to solve this problem. Superior to reported works, the LLZTO obtained by our self-consolidation method can be directly wetted by molten Li without any surface treatment. The self-consolidated LLZTO exhibits a dense microstructure consisting of grains and interstitial phases among them, both of which are accessible to molten Li. Removal of surface contaminants on molten Li rather than that on LLZTO is a prerequisite for direct wetting. Benefiting from direct wetting, an intimate interfacial contact between the LLZTO and Li anode is achieved and the interfacial resistance is significantly reduced. The Li symmetric cell exerts a stable Li plating/stripping cycle for 1000 h at 0.20 mA cm−2 and the solid-state battery paired with LiCoO 2 cathode exhibits a capacity retention of 90.0 % at 0.2 C after 200 cycles at room temperature. This work highlights the surface chemistry of electrolyte and electrode, which is crucial for designing their integration and application. Garnet LLTZO electrolyte prepared by self-consolidation method exhibits an intrinsic lithiophilicity despite the presence of carbonate species on its surface. [Display omitted] • LLTZO can be directly wetted by molten Li without any surface treatment. • LLTZO obtained by our self-consolidation method exhibits intrinsically lithiophilic. • Integration of LLTZO electrolyte with Li anode is achieved by direct wetting. • Removal of surface contaminants on molten Li is a prerequisite for direct wetting. [ABSTRACT FROM AUTHOR]