The rapid capacity loss suffered by P2‐type Mn‐based layered oxide cathode materials, caused by deleterious high‐voltage phase transformations and the dissolution of active materials, greatly limits ...their application in large‐scale sodium‐ion battery installations. In this study, a novel P2/O3 biphasic cathode is developed using a multi‐element (Fe, Mg, and Li) co‐substitution strategy. The results of ex situ X‐ray diffraction analyses and the absence of significant voltage plateaus in the charge–discharge profiles of cells featuring the proposed cathode indicate that deleterious phase transformations and concomitant lattice mismatch in the high‐voltage region are effectively suppressed because of the topotactic intergrown structure of the resulting cathode. The optimized cathode also demonstrates improved structural stability and enhanced Na+ diffusion kinetics, owing to the incorporation of stabilizing dopant pillars and suppressed metal‐ion dissolution. Hence, the resulting Na half cell demonstrates a high initial capacity of 170.5 mA h g−1 at 0.1 C and excellent rate capability (106.6 mA h g−1 at 10 C). Furthermore, the resulting Na full cell, featuring a hard carbon anode, displays excellent cycling stability (72.1% capacity retention after 400 cycles), demonstrating its practical viability. This study presents the design and optimization of high‐performance Mn‐based cathodes.
A novel multi‐element co‐substituted P2/O3 heterostructured cathode material is developed and comprehensively evaluated. Benefiting from its topotactic intergrown structure, the optimized cathode material exhibits smooth phase evolution and less mechanical damage. In addition, the incorporation of low‐valence dopants increases the Na content and alleviates the dissolution of active materials, which improves the Na storage performance.
The topic of sustainable and eco‐friendly energy storage technologies is an issue of global significance. To date, this heavy burden is solely addressed by lithium‐ion battery technology. However, ...the ongoing depletion of limited global lithium resources has restricted their future availability for Li‐ion battery technology, and hence, a significant price increase is expected. This grim situation is the driving force for the development of the “beyond Li‐ion battery” strategy involving alternatives that have several advantages over conventional Li‐ion batteries in terms of cost, durability, safety, and sustainability. Potassium, the closest neighboring alkali element after sodium, offers some unique advantages over lithium and sodium as a charge carrier in rechargeable batteries. Potassium intercalation chemistry in potassium‐ion batteries (KIBs) is successfully demonstrated to be compatible with Li‐ion batteries and sodium‐ion batteries. In addition to KIBs, potassium–sulfur and potassium–oxygen batteries have emerged as new energy‐storage systems due to their low costs and high specific energy densities. This review covers the key technological developments and scientific challenges for a broad range of rechargeable potassium batteries, while also providing valuable insight into the scientific and practical issues concerning the development of potassium‐based rechargeable batteries.
Batteries that use potassium ions, such as potassium‐ion, potassium–sulfur, and potassium–oxygen batteries, are emerging technologies that can compete with lithium‐ion batteries in large‐scale energy‐storage applications. This review covers the key technological developments and scientific challenges for a broad range of potassium‐based batteries, while also providing valuable insight into the scientific and practical issues concerning the development of rechargeable potassium batteries.
The exploitation of effective strategies to accelerate the Na+ diffusion kinetics and improve the structural stability in the electrode is extremely important for the development of high efficientcy ...sodium‐ion batteries. Herein, Se vacancies and heterostructure engineering are utilized to improve the Na+‐storage performance of transition metal selenides anode prepared through a facile two‐in‐one route. The experimental results coupled with theoretical calculations reveal that the successful construction of the Se vacancies and heterostructure interfaces can effectively lower the Na+ diffusion barrier, accelerate the charge transfer efficiency, improve Na+ adsorption ability, and provide an abundance of active sites. Consequently, the batteries based on the constructed ZnSe/CoSe2‐CN anode manifest a high initial Coulombic efficiency (97.7%), remarkable specific capacities (547.1 mAh g–1 at 0.5 A g–1), superb rate capability (362.1 mAh g–1 at 20 A g–1), as well as ultrastable long‐term stability (1000 cycles) with a satisfied specific capacity (535.6 mAh g–1) at 1 A g–1. This work facilitates an in‐depth understanding of the synergistic effect of vacancies and heterojunctions in improving the Na+ reaction kinetics, providing an effective strategy to the rational design of key materials for high efficiency rechargeable batteries.
Vacancy and interface synergistic engineering is utilized to boost the electrochemical performance of bimetallic selenide (ZnSe/CoSe2‐CN)‐based sodium‐ion batteries. The as‐prepared composite manifests appealing Na+‐storage performance, including high initial Coulombic efficiency, good rate capability, and excellent stability. The proposed strategy is considerably facile and may shed light on designing advanced electrodes with intriguing electrochemical performance.
With the ever‐increasing requirement for high‐energy density lithium‐ion batteries (LIBs) to drive pure/hybrid electric vehicles (EVs), considerable attention has been paid to the development of ...cathode materials with high energy densities because they ultimately determine the energy density of LIBs. Notably, the cost of cathode materials is still the main obstacle hindering the extensive application of EVs, with the cost accounting for 40% of the total cost of fabricating LIBs. Therefore, enhancing the energy density and simultaneously decreasing the cost of LIBs are essential for the success of EV/hybrid EV industries. Among the existing commercial cathodes, Ni‐rich layered cathodes are widely employed because of their high energy density, relatively good rate capability, and reasonable cycling performance. Ni‐rich layered cathodes containing Co are now being reconsidered due to the increasing price of Co, which is much higher than that of Ni and Mn. In this report, the recent developments and strategies in the improvement of the stabilities of the bulk and surface for Co‐less Ni‐rich layered cathode materials are reviewed.
A perspective on Co‐less Ni‐rich cathodes for lithium‐ion batteries (LIBs) is provided. LiNiO2, binary‐, ternary‐, and quaternary cathodes are classified as the past, present, and future of LIBs. Surface modification is a strategy for present ternary cathodes. Gradient strategies categorized into five types, from core–shell to hybrid structures, are the foundation for future cathodes to develop.
High‐voltage lithium‐ion batteries (LIBs) enabled by high‐voltage electrolytes can effectively boost energy density and power density, which are critical requirements to achieve long travel ...distances, fast‐charging, and reliable safety performance for electric vehicles. However, operating these batteries beyond the typical conditions of LIBs (4.3 V vs Li/Li+) leads to severe electrolyte decomposition, while interfacial side reactions remain elusive. These critical issues have become a bottleneck for developing electrolytes for applications in extreme conditions. Herein, an additive‐free electrolyte is presented that affords high stability at high voltage (4.5 V vs Li/Li+), lithium‐dendrite‐free features upon fast‐charging operations (e.g., 162 mAh g−1 at 3 C), and superior long‐term battery performance at low temperature. More importantly, a new solvation structure‐related interfacial model is presented, incorporating molecular‐scale interactions between the lithium‐ion, anion, and solvents at the electrolyte–electrode interfaces to help interpret battery performance. This report is a pioneering study that explores the dynamic mutual‐interaction interfacial behaviors on the lithium layered oxide cathode and graphite anode simultaneously in the battery. This interfacial model enables new insights into electrode performances that differ from the known solid electrolyte interphase approach to be revealed, and sets new guidelines for the design of versatile electrolytes for metal‐ion batteries.
A new solvation structure‐related interfacial model is presented, which involves the molecular‐scale interactions between the lithium‐ion, anion, and solvents on the electrolyte–electrode surface, to interpret the high performance enabled by a newly designed high voltage electrolyte. This report is a pioneering study that explores the dynamic mutual‐interaction interfacial behaviors on the Ni‐rich cathode and graphite anode simultaneously in the battery.
Abstract
Doping is a well-known strategy to enhance the electrochemical energy storage performance of layered cathode materials. Many studies on various dopants have been reported; however, a general ...relationship between the dopants and their effect on the stability of the positive electrode upon prolonged cell cycling has yet to be established. Here, we explore the impact of the oxidation states of various dopants (i.e., Mg
2+
, Al
3+
, Ti
4+
, Ta
5+
, and Mo
6+
) on the electrochemical, morphological, and structural properties of a Ni-rich cathode material (i.e., LiNi
0.91
Co
0.09
O
2
). Galvanostatic cycling measurements in pouch-type Li-ion full cells show that cathodes featuring dopants with high oxidation states significantly outperform their undoped counterparts and the dopants with low oxidation states. In particular, Li-ion pouch cells with Ta
5+
- and Mo
6+
-doped LiNi
0.91
Co
0.09
O
2
cathodes retain about 81.5% of their initial specific capacity after 3000 cycles at 200 mA g
−1
. Furthermore, physicochemical measurements and analyses suggest substantial differences in the grain geometries and crystal lattice structures of the various cathode materials, which contribute to their widely different battery performances and correlate with the oxidation states of their dopants.
With the ever-increasing demand for lithium-ion batteries (LIBs) with higher energy density, tremendous attention has been paid to design various silicon-active materials as alternative electrodes ...due to their high theoretical capacity (ca. 3579 mAh g–1). However, totally replacing the commercially utilized graphite with silicon is still insurmountable owing to bottlenecks such as low electrode loading and insufficient areal capacity. Thus, in this study, we turn back to enhanced graphite electrode through the cooperation of modified silicon via a facile and scalable blending process. The modified nano/microstructured silicon with boron doping and carbon nanotube wedging (B–Si/CNT) can provide improved stability (88.2% retention after 200 cycles at 2000 mA g–1) and high reversible capacity (∼2426 mAh g–1), whereas the graphite can act as a tough framework for high loading. Owing to the synergistic effect, the resultant B–Si/CNT–graphite composite (B–Si/CNT@G) shows a high areal capacity of 5.2 mAh cm–2 and excellent cycle retention of 83.4% over 100 cycles, even with ultrahigh active mass loading of 11.2 mg cm–2,which could significantly surpass the commercially used graphite electrode. Notably, the composite also exhibits impressive application in Li-ion full battery using 2 mol % Al-doped full-concentration-gradient LiNi0.76Co0.09Mn0.15O2 (Al2-FCG76) as the cathode with excellent capacity retention of 82.5% even after 300 cycles and an outstanding energy density (8.0 mWh cm–2) based on the large mass loading of the cathode (12.0 mg cm–2).
Li–O2 batteries have received much attention due to their extremely large theoretical energy density. However, the high overpotentials required for charging Li–O2 batteries lower their energy ...efficiency and degrade the electrolytes and carbon electrodes. This problem is one of the main obstacles in developing practical Li–O2 batteries. To solve this problem, it is important to facilitate the oxidation of Li2O2 upon charging by using effective electrocatalysis. Using solid catalysts is not too effective for oxidizing the electronically isolating Li‐peroxide layers. In turn, for soluble catalysts, red‐ox mediators (RMs) are homogeneously dissolved in the electrolyte solutions and can effectively oxidize all of the Li2O2 precipitated during discharge. RMs can decompose solid Li2O2 species no matter their size, morphology, or thickness and thus dramatically increase energy efficiency. However, some negative side effects, such as the shuttle reactions of RMs and deterioration of the Li‐metal occur. Therefore, it is necessary to study the activity and stability of RMs in Li–O2 batteries in detail. Herein, recent studies related to redox mediators are reviewed and the mechanisms of redox reactions are illustrated. The development opportunities of RMs for this important battery technology are discussed and future directions are suggested.
Redox mediators (RMs) for Li−O2 batteries have the potential to solve problems related to limited anodic stability, low round‐trip efficiency, and limited cyclability, which are obstacles in the development of Li−O2 batteries. The status and problems of RMs in Li−O2 batteries are discussed, and the properties and mechanisms of three kinds of RMs: organic, organometallic, and halides, are described.
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