A Tellurium-Boosted High-Areal-Capacity Zinc-Sulfur Battery

Aqueous rechargeable zinc-sulfur (Zn-S) batteries are a promising, cost-effective, and high-capacity energy storage technology. Still, they are challenged by the poor reversibility of S cathodes, sluggish redox kinetics, low S utilization, and unsatisfactory areal capacity. This work develops a facile strategy to achieve an appealing high-areal-capacity (above 5 mAh cm-2) Zn-S battery by molecular-level regulation between S and high-electrical-conductivity tellurium (Te). The incorporation of Te as a dopant allows for manipulation of the Zn-S electrochemistry, resulting in accelerated redox conversion, and enhanced S utilization. Meanwhile, accompanied by the S-ZnS conversion, Te is converted to zinc telluride during the discharge process, as revealed by ex-situ characterizations. This additional redox reaction contributes to the S cathode's total excellent discharge capacity. With this unique cathode structure design, the carbon-confined TeS cathode (denoted as Te1S7/C) delivers a high reversible capacity of 1335.0 mAh g-1 at 0.1 A g-1 with a mass loading of 4.22 mg cm-2, corresponding to a remarkable areal capacity of 5.64 mAh cm-2. Notably, a hybrid electrolyte design uplifts discharge plateau, reduces overpotential, suppresses Zn dendrites growth, and extends the calendar life of Zn-Te1S7 batteries. This study provides a rational S cathode structure to realize high-capacity Zn-S batteries for practical applications.

High-Performance Potassium-Tellurium Batteries Stabilized by Interface Engineering

The emerging potassium-tellurium (K-Te) battery system is expected to realize fast reaction kinetics and excellent rate performance due to the exceptional electrical conductivity of Te. However, there has been a lack of fundamental knowledge about this new K-Te system, including the reaction mechanism and cathode structure design. Herein, a two-step reaction pathway from Te to K₂ Te₃ and ultimately to K₅ Te₃ is investigated in carbonate electrolyte-based K-Te batteries by X-ray diffraction, high-resolution transmission electron microscopy, and selected area electron diffraction characterizations. Additionally, the atomic layer deposition technique is adopted to deposit an ultrathin aluminum oxide (Al₂ O₃ ) film on the electrode surface, which induces the generation of a stable solid electrolyte interphase layer and reduces the loss of active materials effectively. Consequently, the rationally fabricated Te/porous carbon cathode with functional Al₂ O₃ coating delivers remarkable long-term cycling stability over 500 cycles at 1 C with an ultralow capacity decay of only 0.01% per cycle. This interface engineering strategy is validated to stabilize the electrode surface, enhance the structural integrity and ensure reliable electron transfer and K-ion conduction over repeated potassiation/depotassiation cycles. These findings are expected to promote the development of high-energy-density K-S/Se/Te batteries.

Quasi-solid-state lithium-tellurium batteries based on flexible gel polymer electrolytes

A quasi-solid-state Li-Te battery is developed by using a flexible gel polymer electrolyte (GPE), porous carbon/tellurium cathode, and lithium metal anode. The ionic conductivity of GPE is controllable and reaches up to 8.0 × 10^-4 S cm^-1 at 25 °C. The good interfacial contact with Li metal ensures excellent cycling stability in Li/GPE/Li symmetric cells. Moreover, it is found that, compared to S and Se counterparts, the Li-Te battery exhibits good rate capability due to the high electrical conductivity of Te and excellent interfacial stability among GPE, Li, and Te. This work provides several facile strategies to develop safe and high-performance solid-state Li-Te batteries.

Enhanced Potassium Storage Performance for K-Te Batteries via Electrode Design and Electrolyte Salt Chemistry

Potassium batteries are an emerging energy storage technology due to the large abundance of potassium, low cost, and potentially high energy density. However, it remains challenging to find suitable electrode materials with high energy density and good cycling stability due to the structural instability and kinetics issues resulting from large size K⁺. Herein, a durable and high-capacity K-Te battery was developed by rational design of a Te/C electrode and electrolyte salt chemistry. A well-confined Te/C cathode structure was prepared by using a commercially available activated carbon as the Te host via a melt-diffusion method. Compared to bulky Te, the confined Te/C electrode exhibited greatly improved cycling stability, specific capacity, and rate capability in K-Te batteries. Moreover, it was found that the electrolyte salts (KPF₆ and KFSI) had significant impacts on the electrochemical performance of K-Te batteries. The Te/C electrode in the KPF₆-based carbonate electrolyte exhibited higher specific capacity and better rate performance than the Te/C electrode in the KFSI-based one. Mechanism studies revealed that the KPF₆ salt resulted in an organic species-rich solid-electrolyte interphase (SEI) on the Te/C electrode, allowing for fast electron transfer and K-ion diffusion and enhanced K-ion storage performance in K-Te batteries. In contrast, KFSI salt led to the formation of KF-rich SEI layers, which had much higher resistances for electron and K-ion transport and was less effective for the well-confined Te/C electrode. Our work finds that the Te electrode and electrolyte chemistry need to be simultaneously optimized and tailored toward K-ion storage in K-Te batteries. It is expected that the finding reported herein might be inspirable for the future development of K-chalcogen (S/Se/Te) batteries.