Potassium-ion batteries are a promising alternative to lithium-ion batteries. However, it is challenging to achieve fast charging/discharging and long cycle life with the current electrode materials because of the sluggish potassiation kinetics. Here we report a soft carbon anode, namely highly nitrogen-doped carbon nanofibers, with superior rate capability and cyclability. The anode delivers reversible capacities of 248 mAh g–1 at 25 mA g–1 and 101 mAh g–1 at 20 A g–1, and retains 146 mAh g–1 at 2 A g–1 after 4000 cycles. Surface-dominated K-storage is verified by quantitative kinetics analysis and theoretical investigation. A full cell coupling the anode and Prussian blue cathode delivers a reversible capacity of 195 mAh g–1 at 0.2 A g–1. Considering the cost-effectiveness and material sustainability, our work may shed some light on searching for K-storage materials with high performance.

Potassium-ion batteries (KIBs) in organic electrolytes hold great promise as an electrochemical energy storage technology owing to the abundance of potassium, close redox potential to lithium, and similar electrochemistry with lithium system. Although carbon materials have been studied as KIB anodes, investigations on KIB cathodes have been scarcely reported. We for the first time report a comprehensive study on potassium Prussian blue K0.220Fe[Fe(CN)6]0.805·4.01H2O nanoparticles as a potential cathode material. The cathode exhibits a high discharge voltage of 3.1~3.4 V, high reversible capacity of 73.2 mAh g-1 , and great cyclability at both low and high rates with a very small capacity decay rate of ~0.09% per cycle. Electrochemical reaction mechanism analysis identifies the carboncoordinated Fe III /Fe II couple as redox-active site and proves structural stability of the cathode during charge/discharge. Furthermore, for the first time, we present a KIB full-cell by coupling the nanoparticles with commercial carbon materials. The full-cell delivers a capacity of 68.5 mAh g-1 at 100 mA g-1 and retains 93.4% of the capacity after 50 cycles. Considering the low cost and material sustainability as well as the great electrochemical performances, this work may pave the way towards more studies on KIB cathodes and trigger future attention on rechargeable KIBs.

Expanded interlayer spacing and additionally exposed edges induced by defects of MoS2 enable facile K-intercalation, rapid K-transport and promoted K-adsorption.

The next‐generation smart grid for the storage and delivery of renewable energy urgently needs to develop a low‐cost and rechargeable energy storage technology beyond lithium‐ion batteries (LIBs). Owing to the abundance of potassium (K) resources and the similar electrochemical performance to that of LIBs, potassium‐ion batteries (PIBs) have been attracted considerable interest in recent years, and significant progress has been achieved concerning the discovery of high‐performance electrode materials for PIBs. This review especially summarizes the latest research progress regarding anode materials for PIBs, including carbon materials, organic materials, alloys, metal‐based compounds, and other new types of compounds. The reversible K‐ion storage principle and the electrochemical performance (i.e., capacity, potential, rate capability, and cyclability) of these developed anode materials are summarized. Furthermore, the challenges and the corresponding effective strategies to enhance the battery performance of the anode materials are highlighted. Finally, prospects of the future development of high‐performance anode materials for PIBs are discussed.

Oxygen vacancies (OVs) are reported for the first time as an effective strategy to boost the electrochemical performance for amorphous electrode materials of sodium-ion batteries (SIB). Amorphous SnO2 is used as a model anode material to demonstrate the significant impact of OVs owing to the high attention it has received in the SIB field. Amorphous SnO2 ordered arrays are fabricated using the nanoimprinted anodic aluminum oxide (AAO) template and atomic layer deposition, and OVs are confined in the material by annealing the arrays in the N2 atmosphere. The OVs-containing amorphous SnO2 ordered arrays, used as binder-and conductive additive-free anodes, exhibit high reversible capacity and good cycle life by retaining the capacities of 376 mAh g-1 after 100 cycles at 0.05 A g-1 and 220 mAh g-1 after 800 cycles at 1 A g-1 as well as great rate capability by maintaining the capacities of 210 mAh g-1 at 10 A g-1 and 200 mAh g-1 at 20 A g-1. Electrochemical kinetic study reveals that the presence of OVs greatly enhances charge transfer/transport in the amorphous SnO2, thereby boosts the performance comparing with the OVs-free counterpart. This work highlights the importance of modulating defects in amorphous electrode materials towards promoted sodium storage.