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.
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.
Surface stabilization of cathode materials is urgent for guaranteeing long‐term cyclability, and is important in Na cells where a corrosive Na‐based electrolyte is used. The surface of P2‐type ...layered Na2/3Ni1/3Mn2/3O2 is modified with ionic, conducting sodium phosphate (NaPO3) nanolayers, ≈10 nm in thickness, via melt‐impregnation at 300 °C; the nanolayers are autogenously formed from the reaction of NH4H2PO4 with surface sodium residues. Although the material suffers from a large anisotropic change in the c‐axis due to transformation from the P2 to O2 phase above 4 V versus Na+/Na, the NaPO3‐coated Na2/3Ni1/3Mn2/3O2/hard carbon full cell exhibits excellent capacity retention for 300 cycles, with 73% retention. The surface NaPO3 nanolayers positively impact the cell performance by scavenging HF and H2O in the electrolyte, leading to less formation of byproducts on the surface of the cathodes, which lowers the cell resistance, as evidenced by X‐ray photoelectron spectroscopy and time‐of‐flight secondary‐ion mass spectroscopy. Time‐resolved in situ high‐temperature X‐ray diffraction study reveals that the NaPO3 coating layer is delayed for decomposition to Mn3O4, thereby suppressing oxygen release in the highly desodiated state, enabling delay of exothermic decomposition. The findings presented herein are applicable to the development of high‐voltage cathode materials for sodium batteries.
A NaPO3 coating layer functions effectively as cathode for sodium‐ion batteries. The presence of the NaPO3 coating layers scavenges HF and thus lowers the HF content and the amount of water molecules in the electrolyte, which can successfully suppress detachment of the active materials, ensuring better cycling performance and improved thermal stability.
Materials in nature have evolved to the most efficient forms and have adapted to various environmental conditions over tens of thousands of years. Because of their versatile functionalities and ...environmental friendliness, numerous attempts have been made to use bio‐inspired materials for industrial applications, establishing the importance of biomimetics. Biomimetics have become pivotal to the search for technological breakthroughs in the area of rechargeable secondary batteries. Here, the characteristics of bio‐inspired materials that are useful for secondary batteries as well as their benefits for application as the main components of batteries (e.g., electrodes, separators, and binders) are discussed. The use of bio‐inspired materials for the synthesis of nanomaterials with complex structures, low‐cost electrode materials prepared from biomass, and biomolecular organic electrodes for lithium‐ion batteries are also introduced. In addition, nature‐derived separators and binders are discussed, including their effects on enhancing battery performance and safety. Recent developments toward next‐generation secondary batteries including sodium‐ion batteries, zinc‐ion batteries, and flexible batteries are also mentioned to understand the feasibility of using bio‐inspired materials in these new battery systems. Finally, current research trends are covered and future directions are proposed to provide important insights into scientific and practical issues in the development of biomimetics technologies for secondary batteries.
Bio‐inspired materials have technical advantages in application as major components of secondary batteries as well as environmental and economic advantages. The recent research progress on utilization of biomaterials for electrodes, separators, and binders for the improvement of the performance of rechargeable batteries is highlighted and summarized. Current challenges and perspectives regarding the use of biomaterials for secondary batteries are given.
Micrometer‐size LiFePO4 spheres with homogeneous double carbon coating layers have been prepared as potential electrode materials for battery applications. The double carbon‐coated LiFePO4 electrodes ...in a lithium‐ion cell exhibited discharge capacities of the order of 160 mAh g−1 and 115 mAh g−1 at 25 °C under 0.1 C‐rate and 10 C‐rate, respectively.
Herein, Ti4+ in P′2‐Na0.67(Mn0.78Fe0.22)0.9Ti0.1O2 is proposed as a new strategy for optimization of Mn‐based cathode materials for sodium‐ion batteries, which enables a single phase reaction during ...de‐/sodiation. The approach is to utilize the stronger Ti–O bond in the transition metal layers that can suppress the movements of Mn–O and Fe–O by sharing the oxygen with Ti by the sequence of Mn–O–Ti–O–Fe. It delivers a discharge capacity of ≈180 mAh g−1 over 200 cycles (86% retention), with S‐shaped smooth charge–discharge curves associated with a small volume change during cycling. The single phase reaction with a small volume change is further confirmed by operando synchrotron X‐ray diffraction. The low activation barrier energy of ≈541 meV for Na+ diffusion is predicted using first‐principles calculations. As a result, Na0.67(Mn0.78Fe0.22)0.9Ti0.1O2 can deliver a high reversible capacity of ≈153 mAh g−1 even at 5C (1.3 A g−1), which corresponds to ≈85% of the capacity at 0.1C (26 mA g−1). The nature of the sodium storage mechanism governing the ultrahigh electrode performance in a full cell with a hard carbon anode is elucidated, revealing the excellent cyclability and good retention (≈80%) for 500 cycles (111 mAh g−1) at 5C (1.3 A g−1).
The substitution of Mn with Fe3+ and Ti4+ in P′2‐type Na0.67(Mn0.78Fe0.22)0.9Ti0.1O2 leads to the suppression of phase transitions with an increased average Mn oxidation state. Therefore, it delivers high reversible capacity during cycling with a small volume change. Above all, it shows excellent high rate capability, accompanied by low activation barrier energy of ≈541 meV for Na+ diffusion.
In this work, rhombohedral KTi2(PO4)3 is introduced to investigate the related theoretical, structural, and electrochemical properties in K cells. The suggested KTi2(PO4)3 modified by ...electro‐conducting carbon brings about a flat voltage profile at ≈1.6 V, providing a large capacity of 126 mAh (g‐phosphate)−1, corresponding to 98.5% of the theoretical capacity, with 89% capacity retention for 500 cycles. Structural analyses using electrochemical performance measurements, first‐principles calculations, ex situ X‐ray absorption spectroscopy, and operando X‐ray diffraction provide new insights into the reaction mechanism controlling the (de)intercalation of potassium ions into the host KTi2(PO4)3 structure. It is observed that a biphasic redox process by Ti4+/3+ occurs upon discharge, whereas a single‐phase reaction followed by a biphasic process occurs upon charge. Along with the structural refinement of the electrochemically reduced K3Ti2(PO4)3 phase, these new findings provide insight into the reaction mechanism in Na superionic conductor (NASICON)‐type KTi2(PO4)3. The present approach can also be extended to the investigation of other NASICON‐type materials for potassium‐ion batteries.
The mechanism that guides the insertion/extraction of K+ into/from KTi2(PO4)3 structure is clarified by operando X‐ray diffraction, X‐ray absorption near‐edge structure, and first‐principles calculations. A two‐phase reaction activated by Ti4+/Ti3+ is responsible for high cycling stability over the 500 cycles with capacity retention of 89%.
The zinc-ion battery (ZIB) is a 2 century-old technology but has recently attracted renewed interest owing to the possibility of switching from primary to rechargeable ZIBs. Nowadays, ZIBs employing ...a mild aqueous electrolyte are considered one of the most promising candidates for emerging energy storage systems (ESS) and portable electronics applications due to their environmental friendliness, safety, low cost, and acceptable energy density. However, there are many drawbacks associated with these batteries that have not yet been resolved. In this Review, we present the challenges and recent developments related to rechargeable ZIB research. Recent research trends and directions on electrode materials that can store Zn2+ and electrolytes that can improve the battery performance are comprehensively discussed.
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