Lithium (Li) metal battery is considered the most promising next‐generation battery due to its low potential and high theoretical capacity. However, Li dendrite growth causes serious safety problems. ...Herein, the 15‐Crown‐5 (15‐C‐5) is reported as an electrolyte additive based on solvation shell regulation. The strong complex effect between Li+ ion and 15‐C‐5 can reduce the concentration of Li ions on the electrode surface, thus changing the nucleation, and repressing the growth of Li dendrites in the plating process. Significantly, the strong coordination of Li+/15‐C‐5 would be able to make them aggregate around the Li crystal surface, which could form a protective layer and favor the formation of a smooth and dense solid electrolyte interphase with high toughness and Li+ ion conductivity. Therefore, the electrolyte system with 2.0 wt% 15‐C‐5 achieves excellent electrochemical performance with 170 cycles at 1.0 mA cm−2 with capacity of 0.5 mA h cm−2 in symmetric Li|Li cells. The obviously enhanced cycle and rate performance are also achieved in Li|LiNi0.6Co0.2Mn0.2O2 (NCM622) full cells. The 15‐C‐5 demonstrates to be a promising additive for the electrolytes toward safe and efficient Li metal batteries.
Owing to the strong coordination ability, 15‐Crown‐5 (15‐C‐5) ether can coordinate with Li+ to form a Li+/15‐C‐5 protective layer in Li surface and favor the formation of smooth and dense solid electrolyte interphase films with high Li+ conductivity. This is found to be effective to enable high‐performance electrolytes for Li metal batteries with a life span of 170 cycles.
In this work, we fabricate the oxygen/sulfur co-doped hard carbon through a facile hydrolyzation/sulfuration process of skimmed cotton. The obtained carbon exhibits superior potassium storage ...properties.
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Hard carbon is regarded as promising anode materials for potassium-ion batteries (KIBs) owing to their low price and easy availability. However, the limited rate capability still needs to be improved. Herein, we demonstrate the fabrication of oxygen/sulfur co-doped hard carbon through a facile hydrolyzation-sulfuration process of skimmed cotton. The simultaneous dopants significantly improve potassium ion diffusion rate. When served as the anode for KIBs, this hydrolyzed hard carbon delivered a high reversible capacity (409 mAh/g at 0.1 A/g), superior rate capability (135 mAh/g at 2 A/g) and excellent cyclability (about 120 mAh/g overt 500 cycles at 2 A/g). This work provides a facile strategy to prepare low-cost doped-hard carbon with superior potassium storage property.
In this roadmap, two-dimensional materials including graphene, black phosporus, MXenes, covalent organic frameworks, oxides, chalcogenides, and others, are highlighted in energy storage and ...conversion.
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Energy storage and conversion have attained significant interest owing to its important applications that reduce CO2 emission through employing green energy. Some promising technologies are included metal-air batteries, metal-sulfur batteries, metal-ion batteries, electrochemical capacitors, etc. Here, metal elements are involved with lithium, sodium, and magnesium. For these devices, electrode materials are of importance to obtain high performance. Two-dimensional (2D) materials are a large kind of layered structured materials with promising future as energy storage materials, which include graphene, black phosporus, MXenes, covalent organic frameworks (COFs), 2D oxides, 2D chalcogenides, and others. Great progress has been achieved to go ahead for 2D materials in energy storage and conversion. More researchers will join in this research field. Under the background, it has motivated us to contribute with a roadmap on ‘two-dimensional materials for energy storage and conversion.
Lithium metal batteries suffer from short lifespans and low Coulombic efficiency (CE) due to the high reactivity of Li and the poor stability of the solid electrolyte interphase (SEI). Herein, we ...propose the concept of a pseudo-concentrated electrolyte (PCE) induced by an electron-deficient additive (4-pyridylboronic acid; 4-PBA) to form a robust, LiF-rich SEI, thus addressing the above issues. Molecular dynamics simulations confirm that 4-PBA can increase the coordination number of PF6- anions in the Li+ solvation sheath to achieve pseudo-concentrated LiPF6 in the electrolyte. Moreover, the 4-PBA can scavenge harmful PF5 decomposed from LiPF6 to stabilize the LiF-rich SEI. The resulting robust LiF-rich SEI promotes Li growth along the SEI/Li interface and represses the growth of Li dendrites. Thus, excellent performance is achieved, with a high CE of 97.1% for a Li||Cu cell at 1.0 mA cm−2, and over 950 cycles at 0.5 mA cm−2 for Li||Li symmetric cells with 1.0 wt% 4-PBA electrolyte. Meanwhile, the resulting stable boron-containing cathode electrolyte interphase enables Li||LiNi0·6Co0·2Mn0·2O2 (NCM622) cells to achieve excellent stability, with a capacity retention of 86.9% after 200 cycles.
We propose the concept of a pseudo-concentrated electrolyte that helps in the formation of a robust LiF-rich SEI for uniform Li deposition, which is realized by the induction of 4-pyridineboronic acid (4-PBA) to increase PF6− coordination with Li+. Display omitted
•The concept of a pseudo-concentrated electrolyte is presented.•4-pyridylboronic acid can increase the coordination number of PF6– anions in the Li+ solvation sheath.•As an additive, 4-pyridylboronic acid can have a pseudo-concentrated effect on electrolytes.•4-pyridylboronic acid can scavenge harmful PF5 in the electrolyte.
The performance of Li batteries is influenced by the Li+ solvation structure, which can be precisely adjusted by the components of the electrolytes. In this review, we overview the strategies for ...optimizing electrolyte solvation structures from three different perspectives, including anion regulation, binding energy regulation, and additive regulation. These strategies can optimize the composition of the electrode‐electrolyte interface, enhance the anti‐oxidative stability of electrolytes as well as regulate the behaviors of anions, solvents, and Li+ during the cycling process. Moreover, we also provide our insights into these aspects as well as present perspectives on high‐performance Li batteries.
In this review, we discuss about the structural regulation chemistry of lithium ion solvation for lithium batteries, from the strategies for optimizing electrolyte solvation structures to perspectives on high‐performance Li batteries.
Lithium batteries are currently the most popular and promising energy storage system, but the current lithium battery technology can no longer meet people's demand for high energy density devices. ...Increasing the charge cutoff voltage of a lithium battery can greatly increase its energy density. However, as the voltage increases, a series of unfavorable factors emerges in the system, causing the rapid failure of lithium batteries. To overcome these problems and extend the life of high‐voltage lithium batteries, electrolyte modification strategies have been widely adopted. Under this content, this review first introduces the degradation mechanism of lithium batteries under high cutoff voltage, and then presents an overview of the recent progress in the modification of high‐voltage lithium batteries using electrolyte modification strategies. Finally, the future direction of high‐voltage lithium battery electrolytes is also proposed.
High‐voltage lithium batteries have some challenges, e.g., electrolyte decomposition, parasitic oxidation reaction, transition metal dissolution and surface cracks and phase changes in regards with cathodes. In this review, we will overview the recent progress in the modification of high‐voltage lithium batteries using electrolyte modification strategies, and propose future research directions.
We synthesize the porous sulfur-doped porous hard carbon by templated method, which exhibits a long cycling life with ∼191 mAh/g after 300 cycles at 1 A/g, and an excellent rate capability with ∼100 ...mAh/g at 5 A/g for potassium storage.
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Hard carbon is promising anode for potassium-ion batteries (PIBs), however, the poor rate capability hinders its development as potential anode. To address this question, we design a sulfur-doped porous hard carbon (S-HC) for PIBs through the combination of structural design and composition adjustment. The as-designed S-HC exhibits a long cycling life with ∼191 mA h/g after 300 cycles at 1 A/g, and an excellent rate capability with ∼100 mA h/g at 5 A/g, which was attributed to its structural characteristics and compositions. The S-HC demonstrates to be promising anode in the future.
The performance of lithium metal batteries (LMBs) is determined by many factors from the bulk electrolyte to the electrode‐electrolyte interphases, which are crucially affected by electrolyte ...additives. Herein, the authors develop the heptafluorobutyrylimidazole (HFBMZ) as a hexa‐functional additive to inhibit the dendrite growth on the surface of lithium (Li) anode, and then improve the cycling performance and rate capabilities of Li||LiNi0.6Co0.2Mn0.2O2 (NCM622). The HFBMZ can remove the trace H2O and HF from the electrolyte, reducing the by‐products on the surface of solid electrolyte interphase (SEI) and inhibiting the dissolution of metal ions from NCM622. Also, the HFBMZ can enhance the wettability of the separator to promote uniform Li deposition. HFBMZ can make Li+ easy to be desolvated, resulting in the increase of Li+ flux on Li anode surface. Moreover, the HFBMZ can optimize the composition and structure of SEI. Therefore, the Li||Li symmetrical cells with 1 wt% HFBMZ‐contained electrolyte can achieve stable cycling for more than 1200 h at 0.5 mA cm–2. In addition, the capacity retention rate of the Li||NCM622 can reach 92% after 150 cycles at 100 mA g–1.
Heptafluorobutyrylimidazole (HFBMZ) can be used as a hexa‐functional additive to remove trace H2O and HF from electrolyte, enhance the wettability of separator, make Li+ desolvated easily, and obtain stable solid electrolyte interphase (SEI) and CEI to improve the performance of lithium metal battery.
High‐voltage nickel (Ni)‐rich layered oxide‐based lithium metal batteries (LMBs) exhibit a great potential in advanced batteries due to the ultra‐high energy density. However, it is still necessary ...to deal with the challenges in poor cyclic and thermal stability before realizing practical application where cycling life is considered. Among many improved strategies, mechanical and chemical stability for the electrode electrolyte interface plays a key role in addressing these challenges. Therefore, extensive effort has been made to address the challenges of electrode‐electrolyte interface. In this progress, the failure mechanism of Ni‐rich cathode, lithium metal anode and electrolytes are reviewed, and the latest breakthrough in stabilizing electrode‐electrolyte interface is also summarized. Finally, the challenges and future research directions of Ni‐rich LMBs are put forward.
Lithium metal batteries show the great potential in advanced batteries due to their ultra‐high energy density. This article discusses the failure mechanisms of Ni‐rich cathodes, lithium metal anodes, and electrolytes, and overviews the latest breakthroughs in stabilizing the electrode electrolyte interface from the aspect of electrolytes.
The safety and electrochemical performance of rechargeable lithium‐metal batteries (LMBs) are primarily influenced by the additives in the organic liquid electrolytes. However, multi‐functional ...additives are still rarely reported. Herein, we proposed heptafluorobutyric anhydride (HFA) as a qua‐functional additive to optimize the composition and structure of the solid electrolyte interphase (SEI) at the electrode/electrolyte interface. The reduction/oxidation decomposition of the fluorine‐rich HFA facilitate uniform inorganic‐rich SEI and compact cathode electrolyte interphase (CEI) formation, which enables stable lithium plating during charge and suppresses the dissolution of transition‐metal ions. Moreover, HFA optimizes the Li‐ion solvation for stable Li plating/stripping and serves as the surfactant to enhance the wettability of the separator by the electrolyte to increase Li‐ion flux. The symmetric Li∥Li cell with 1.0 wt % HFA electrolyte had an excellent cycling performance over 340 h at 1.0 mA cm−2 with a capacity of 0.5 mAh cm−2 while the Li∥NCM622 cell maintained high capacity retention after 250 cycles and outstanding rate performance even at 15 C.
Heptafluorobutyric anhydride (HFA) is proposed as qua‐functional additive to optimize anode(cathode)/electrolyte interphases and Li‐ion flux/solvation. The reduction/oxidation decomposition and high fluorine content of HFA facilitate the formation of a uniform inorganic‐rich solid electrolyte interphase (SEI) for depositing Li evenly, to form a compact cathode electrolyte interphase (CEI) to reduce the dissolution of transition metal ions.
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