The wet‐chemical processability of sulfide solid electrolytes (SEs) provides intriguing opportunities for all‐solid‐state batteries. Thus far, sulfide SEs are wet‐prepared either from solid ...precursors suspended in solvents (suspension synthesis) or from homogeneous solutions using SEs (solution process) with restricted composition spaces. Here, a universal solution synthesis method for preparing sulfide SEs from precursors, not only Li2S, P2S5, LiCl, and Na2S, but also metal sulfides (e.g., GeS2 and SnS2), fully dissolved in an alkahest: a mixture solvent of 1,2‐ethylenediamine (EDA) and 1,2‐ethanedithiol (EDT) (or ethanethiol). Raman spectroscopy and theoretical calculations reveal that the exceptional dissolving power of EDA–EDT toward GeS2 is due to the nucleophilicity of the thiolate anions that is strong enough to dissociate the GeS bonds. Solution‐synthesized Li10GeP2S12, Li6PS5Cl, and Na11Sn2PS12 exhibit high ionic conductivities (0.74, 1.3, and 0.10 mS cm−1 at 30 °C, respectively), and their application for all‐solid‐state batteries is successfully demonstrated.
The universal solution synthesis of sulfide solid electrolytes is first demonstrated. The alkahest solvent, 1,2‐ethylenediamine–1,2‐ethanedithiol, fully dissolves not only Li2S (or Na2S), P2S5, and LiCl, but also metal sulfides (e.g., GeS2 and SnS2), forming homogeneous solid electrolyte solutions. Solution‐synthesized Li10GeP2S12, Li6PS5Cl, and Na11Sn2PS12 exhibit high ionic conductivities, and their applicability to all‐solid‐state batteries is successfully demonstrated.
The rational design of bifunctional electrocatalyst through simple synthesis with high activity remains a challenging task. Herein, Na/Al codoped Li‐excess Li‐Ru‐Ni‐O layered electrodes are ...demonstrated with defects/dislocations as an efficient bifunctional electrocatalyst toward lithium‐ion battery (LIB) and oxygen evolution reaction (OER). Toward LIB cathode, specific capacity of 173 mAh g−1 (0.2C‐rate), cyclability (>95.0%), high Columbic efficiency (99.2%), and energy efficiency (90.7%) are achieved. The codoped electrocatalyst has exhibited OER activity at a low onset potential (270 mV@10 mA cm−2), with a Tafel slope 69.3 mV dec−1, and long‐term stability over 36 h superior to the undoped and many other OER electrocatalysts including the benchmark IrO2. The concurrent doping resides in the crystal lattice (where Na shows the pillaring effect to improve facile Li diffusion), Al improves the stabilization of the layered structure, and defective structures provide abundant active sites to accelerate OER reactions.
A bifunctional electrocatalyst of high activity through simple synthesis is rationally designed. Pre‐constructed defects achieved via codoping Na‐Al in Li‐rich systems seem to promise improvements in lithium batteries’ reversible capacities and significantly boost the oxygen evolution reactions. Na shows the pillaring effect and Al stabilizes the layered structure, doubly benefitting the material.
Abundant availability of seawater grants economic and resource‐rich benefits to water electrolysis technology requiring high‐purity water if undesired reactions such as chlorine evolution reaction ...(CER) competitive to oxygen evolution reaction (OER) are suppressed. Inspired by a conceptual computational work suggesting that OER is kinetically improved via a double activation within 7 Å‐gap nanochannels, RuO2 catalysts are realized to have nanoscopic channels at 7, 11, and 14 Å gap in average (dgap), and preferential activity improvement of OER over CER in seawater by using nanochanneled RuO2 is demonstrated. When the channels are developed to have 7 Å gap, the OER current is maximized with the overpotential required for triggering OER minimized. The gap value guaranteeing the highest OER activity is identical to the value expected from the computational work. The improved OER activity significantly increases the selectivity of OER over CER in seawater since the double activation by the 7 Å‐nanoconfined environments to allow an OER intermediate (*OOH) to be doubly anchored to Ru and O active sites does not work on the CER intermediate (*Cl). Successful operation of direct seawater electrolysis with improved hydrogen production is demonstrated by employing the 7 Å‐nanochanneled RuO2 as the OER electrocatalyst.
In this work, a nanochanneled‐RuO2 catalyst is experimentally demonstrated using lithiation and de‐lithiation of RuO2 nanoparticles. An associative activation that works on a single specific peroxide intermediate (OOH) enables the selectively enhanced electrochemical oxygen evolution reaction to compare with the chlorine evolution reaction by breaking linear scaling relationships.
Understanding the local cation order in the crystal structure and its correlation with electrochemical performances has advanced the development of high‐energy Mn‐rich cathode materials for Li‐ion ...batteries, notably Li‐ and Mn‐rich layered cathodes (LMR, e.g., Li1.2Ni0.13Mn0.54Co0.13O2) that are considered as nanocomposite layered materials with C2/m Li2MnO3‐type medium‐range order (MRO). Moreover, the Li‐transport rate in high‐capacity Mn‐based disordered rock‐salt (DRX) cathodes (e.g., Li1.2Mn0.4Ti0.4O2) is found to be influenced by the short‐range order of cations, underlining the importance of engineering the local cation order in designing high‐energy materials. Herein, the nanocomposite is revealed, with a heterogeneous nature (like MRO found in LMR) of ultrahigh‐capacity partially ordered cathodes (e.g., Li1.68Mn1.6O3.7F0.3) made of distinct domains of spinel‐, DRX‐ and layered‐like phases, contrary to conventional single‐phase DRX cathodes. This multi‐scale understanding of ordering informs engineering the nanocomposite material via Ti doping, altering the intra‐particle characteristics to increase the content of the rock‐salt phase and heterogeneity within a particle. This strategy markedly improves the reversibility of both Mn‐ and O‐redox processes to enhance the cycling stability of the partially ordered DRX cathodes (nearly ≈30% improvement of capacity retention). This work sheds light on the importance of nanocomposite engineering to develop ultrahigh‐performance, low‐cost Li‐ion cathode materials.
The multi‐phase heterogeneous nature of ultrahigh‐energy Mn‐based partially disordered cathodes is revealed by combined experimental and computational studies. This fundamental understanding enables the novel nanocomposite design, which controls a phase fraction within a single particle. Consequently, T30 cathode via a nanocomposite engineering shows more reversible redox properties and a superior cycle retention, showing new insights into developing advanced Mn‐based cathodes.
Surface coating on alloy anodes renders an effective remedy to tolerate internal stress and alleviate the side reaction with electrolytes for long-lasting reversible lithium redox reactions in ...lithium-ion batteries. However, the role of surface coating on the interparticle connections of alloy anodes remains not fully understood. Herein, we exploit real-time lithiation and mechanic measurement of SnO2 nanoparticles via in situ TEM with different coating layers, including conducting polymer polypyrrole and metal oxide MnO2. As a result, polypyrrole is more flexible to accommodate the volume expansion issue. More importantly, the polypyrrole coating layers offer a large contact area and strong adhesion force between the SnO2 nanoparticles, ensuring fast lithiation kinetics and high cycling stability. These observations provide new insight into how the interparticle connections of alloy anodes with diverse coating approaches can impact battery performance, shedding light on the practical processing of the alloy anode materials for high-energy Li-ion batteries.
The practical use of silicon anodes is interfered by the following key factors: volume expansion, slow kinetics, and low electrical and ionic conductivities. Many studies have focused on surface ...engineering from the particle to electrode level to achieve stability and energy density. Herein, simple nitrogen gas plasma is introduced as a surface treatment method for silicon-based electrodes to avoid the problems of material synthesis-based functionalizations (e.g., high cost, time consuming, and low quality). The introduction of activated nitrogen gas on electrode surfaces changes the binding energy and resistance of silicon, increasing the reversibility of the charge/discharge reaction of silicon-based anodes. In addition, such doping and dehydrogenation of the electrode surface improve reaction kinetics to 876 mA h g–1 specific capacity at 8.5 A g–1 in silicon/graphite anodes even with a high silicon content of 40%. The proposed strategy, through nitrogen plasma, offers advantages for direct functionalization on electrode surfaces by a simple method.
Over the past decade, lithium metal has been considered the most attractive anode material for high-energy-density batteries. However, its practical application has been hindered by its high ...reactivity with organic electrolytes and uncontrolled dendritic growth, resulting in poor Coulombic efficiency and cycle life. In this paper, we propose a design strategy for interface engineering using a conversion-type reaction of metal fluorides to evolve a LiF passivation layer and Li-M alloy. Particularly, we propose a LiF-modified Li-Mg-C electrode, which demonstrates stable long-term cycling for over 2000 h in common organic electrolytes with fluoroethylene carbonate (FEC) additives and over 700 h even without additives, suppressing unwanted side reactions and Li dendritic growth. With the help of phase diagrams, we found that solid-solution-based alloying not only facilitates the spontaneous evolution of a LiF layer and bulk alloy but also enables reversible Li plating/stripping inward to the bulk, compared with intermetallic compounds with finite Li solubility.
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