Correlation between SEI solubility and SEI components

Previously, SEI solubility is a "black box", where SEI formation, dissolution, SEI-solvent interaction are coupled together. This study quantifies intrinsic SEI solubility by introducing two sets of electrolytes, SEI preformation electrolytes and SEI dissolution electrolytes, and decouples the "solute-solution" interplay.

As result, the solubility of a typical organic-rich SEI is 3.3 times that of a typical inorganic-rich one. A feasible strategy to preform an insoluble SEI leads to a record-high Na inventory reversibility of 99.95% over 900 cycles.  

Discovering high-efficiency Na inventory additives via high-throughput screening

Interfacial Na loss is much more severe than Li loss, and no mature technology has been appropriately set up to compensate for this Na loss.

Through high-throughput screening, this study identifies 52 promising candidates as potential Na inventory additives. Among them, Na4FeO4 demonstrated 451 mAh g-1 irreversible capacity at 4.5 V, and impressively, 426 mAh g-1 (94.5%) at a moderate 4.0 V. This significant Na inventory supply leads to a 14.7 to 24.5% increase in energy density, apart from enhanced cycle life.

In situ electrochemical transmission electron microscopy for SEI characterization

The solid-electrolyte interphase (SEI), a passivation layer formed between the anode and the electrolyte in lithium-ion batteries, can degrade over time due to long-term operation or calendar ageing. This degradation is often accompanied by the continuous consumption of the battery’s limited lithium inventory and is largely influenced by the initial physicochemical properties of the SEI. However, a single technique is rarely sufficient to characterize these properties. In situ electrochemical transmission electron microscopy (TEM) enables an operando assessment of the morphology, composition, structure and electrical properties of the SEI layer. 

A photothermal interface design for efficient resource recovery

Recovering ammonia (NH3) from ammonium (NH4+)-containing wastewater simultaneously achieves resource recovery and wastewater treatment. Given that NH3 recovery involves a reversible NH4+ hydrolysis reaction, traditional strategy requires alkaline reactants for promoting the reaction forward and energy-intensive heating for recovering NH3, resulting in substantial cost and energy consumption. Here we propose a solar-driven NH3 recovery strategy enabled by floatable amino-grafted (‒NH2) MXene (Ti3C2)-based sponge that possesses local alkaline environment and interfacial heat on water surface. Taking ammonia chloride (NH4Cl) wastewater for example, a NH3 recovery rate of 0.6 mol m−2 h−1 with a purity of 99.8% is obtained under 5 sun without extra reagents and energy consumption, and the recovered NH3 can be directly used as nitrogen fertilizer. Life-cycle and techno-economic assessments highlight the advantages of solar-driven NH3 recovery in terms of environmental benefits and economic potential. 

Understanding and mitigating Li inventory loss

Anode-less Li batteries are an ideal cell architecture for energy-dense, low-cost, and resource-sustainable applications. However, fast Li inventory loss limits this cell design to only a few tens of cycles. This study reports the spatiotemporal design of SEI for maximizing Li inventory reversibility.

As a result, Li inventory loss has been mitigated by more than one order of magnitude in Ah-level pouch cells. This study also discusses potential future directions for sustainable SEI design.