Recent Progress and Perspective in Electrode Materials for K‐Ion Batteries

Abstract

and demand in terms of time and space. Thus, grid-level stationary energy storage systems (ESSs) play a key role in making renewable energies both effective and efficient and thereby shaping a more sustainable and environmental friendly society.Although different energy storage technologies including mechanical, electrical, chemical, and electrochemical systems have been proposed, [2,3] mechanical energy storage through pumped hydroelectricity currently dominates the market (≈95% of the installed capacity, ≈183 GW). [4] Electrochemical energy storage is also being considered as a promising option for ESSs based on its flexibility of deployment with little restriction on size and geographical location, low maintenance costs, large energy density, high round-trip efficiency, and long cycle life. [3,5,6] The market for Li-ion batteries (LIBs), originally commercialized for portable electronic devices (i.e., cell phones and laptops), is now expanding to electric vehicles (EVs) and gridlevel ESSs. However, it remains debatable whether the global Li reserves, ≈14 million tons, can meet the increasing demand for such large-scale applications. [7][8][9] The price of lithium carbonate, which is a primary precursor for LIBs, has been continuously increasing since 2000, [10] and this trend is likely to accelerate once the EV and ESS markets take off. Moreover, Li is geographically limited to specific regions: ≈86% of the Li reserves are located in Bolivia, Chile, China, Argentina, and Australia; [9] therefore, geopolitical issues may arise. A more pressing issue for Li-ion markets is the use of Co in all high-energy-density systems. With more than 50% of all mined Co destined for use in Li-ion technology, and a substantial fraction of that coming from the Democratic Republic of the Congo, Li-ion growth may be hampered by the availability of Co. [11] As a less expensive alternative to LIBs, Na-ion batteries (NIBs) have been extensively studied. [6,[12][13][14] The relatively high standard redox potential of Na/Na + leads to a lower working voltage and thereby lower energy density than Li-ion. In addition, hard carbon, which is associated with a high production cost and low material's density, must be used as an anode in NIBs, as graphite, which is the standard anode for LIBs, cannot store Na ions. [15][16][17] Recently, K-ion batteries (KIBs) have emerged as another possible energy storage system. [18][19][20] It is notable that the abundance of K resources in the Earth's crust and oceans is similar to that of Na (Figure 1a). [21,22] The cost of potassium carbonate The development of rechargeable batteries using K ions as charge carriers has recently attracted considerable attention in the search for cost-effective and large-scale energy storage systems. In light of this trend, various materials for positive and negative electrodes are proposed and evaluated for application in K-ion batteries. Here, a comprehensive review of ongoing materials research on nonaqueous K-ion batteries is offered. Information on the status of ...

Development of P3-K0.69CrO2 as an ultra-high-performance cathode material for K-ion batteries

“…The formation of P3-K 0.69 CrO 2 after the electrochemical ion-exchange process is reasonable compared with the previously reported P3-type layered oxide materials. 8,11 Upon further extraction of K ions beyond B0.47 mol, the calculated formation energy of the P3-K 0.69 CrO 2 cathode was less energetically favorable, causing irreversible capacity loss. The poor cycling performance of the P3-K 0.69 CrO 2 cathode in the wide voltage range of 1.5-4.0 V confirms that our computational result is reasonable (Fig.…”

Dopant Segregation Boosting High‐Voltage Cyclability of Layered Cathode for Sodium Ion Batteries

“…[7,8] Either in the form of O3 structure, P2 structure or other else structures, their common similarity is the layer by layer stacking sequence of transition metal ions, oxygen ions, and alkaline ions. [7,8] Either in the form of O3 structure, P2 structure or other else structures, their common similarity is the layer by layer stacking sequence of transition metal ions, oxygen ions, and alkaline ions.…”

K‐Birnessite Electrode Obtained by Ion Exchange for Potassium‐Ion Batteries: Insight into the Concerted Ionic Diffusion and K Storage Mechanism

“…[3] Owing to the low-cost [4] and low standard potential [5] of potassium (K), KIBs could in principle offer cost-effectiveness and higher energy density, which would lead to a substantial advance in energy storage technology. [3] Owing to the low-cost [4] and low standard potential [5] of potassium (K), KIBs could in principle offer cost-effectiveness and higher energy density, which would lead to a substantial advance in energy storage technology.…”