2023 roadmap for potassium-ion batteries

The heavy reliance of lithium-ion batteries (LIBs) has caused rising concerns on the sustainability of lithium and transition metal and the ethic issue around mining practice. Developing alternative energy storage technologies beyond lithium has become a prominent slice of global energy research portfolio. The alternative technologies play a vital role in shaping the future landscape of energy storage, from electrified mobility to the efficient utilization of renewable energies and further to large-scale stationary energy storage. Potassium-ion batteries (PIBs) are a promising alternative given its chemical and economic benefits, making a strong competitor to LIBs and sodium-ion batteries for different applications. However, many are unknown regarding potassium storage processes in materials and how it differs from lithium and sodium and understanding of solid–liquid interfacial chemistry is massively insufficient in PIBs. Therefore, there remain outstanding issues to advance the commercial prospects of the PIB technology. This Roadmap highlights the up-to-date scientific and technological advances and the insights into solving challenging issues to accelerate the development of PIBs. We hope this Roadmap aids the wider PIB research community and provides a cross-referencing to other beyond lithium energy storage technologies in the fast-pacing research landscape

Trimming the Degrees of Freedom via a K+ Flux Rectifier for Safe and Long-Life Potassium-Ion Batteries

Highlights High Coulombic efficiency of over 99% for dendrite-free K||Cu cell after 820 cycles. Year-scale-cycling performance of organic PTCDI cathode over 2,100 cycles. Flexible device demonstration such as fibre cell still could operate when cut into three fibre cells

Design strategies for high-energy-density aqueous zinc batteries

In recent years, the increasing demand for high-capacity and safe energy storage has focused attention on zinc batteries featuring high voltage, high capacity, or both. Despite extensive research progress, achieving high-energy-density zinc batteries remains challenging and requires the synergistic regulation of multiple factors including reaction mechanisms, electrodes, and electrolytes. In this Review, we comprehensively summarize the rational design strategies of high-energy-density zinc batteries and critically analyze the positive effects and potential issues of these strategies in optimizing the electrochemistry, cathode materials, electrolytes, and device architecture. Finally, the challenges and perspectives for the further development of high-energy-density zinc batteries are outlined to guide research towards new-generation batteries for household appliances, low-speed electric vehicles, and large-scale energy storage systems.Ministry of Education (MOE)Submitted/Accepted versionThis work was supported by the National Natural Science Foundation of China (Grant Nos. 51972346, 51932011), the Hunan Outstanding Youth Talents (2021JJ10064), the Program of Youth Talent Support for Hunan Province (2020RC3011), and the Innovation-Driven Project of Central South University (No. 2020CX024). H.J.F. acknowledges the financial support from the Ministry of Education by a Tier 1 grant (RG157/19)

Superstable potassium metal batteries with a controllable internal electric field

Stable potassium metal batteries (PMBs) are promising candidates for electrical energy storage due to their ability to reversibly store electrical energy at a low cost. However, dendritic growth and large volume changes hinder their practical application. Here, referring to the morphology and structure of a virus, a bionic virus-like-carbon microsphere (BVC) was designed as the anode host for a PMB. A BVC with a three-dimensional structure can not only control the electric field, which can suppress dendrite formation, but can also provide a larger space to accommodate the volume change during the cycle progress. The designed potassium (K) metal anode exhibits excellent cycle life and stability (during 1800 h of repeated plating/stripping of K at a current density of 0.1 mA cm−2, K-BVC can realize a very stable K metal anode with low voltage hysteresis). Stable cyclability and improved rate capability can be realized in a full cell using Prussian blue over 400 cycles. This research provides a new idea for the development of stable K metal anodes and may pave the way for the practical application of next-generation metal batteries

An Organic Cathode for Potassium Dual-Ion Full Battery

Potassium-based dual-ion full batteries (PDIBs) were developed with graphite anode, polytriphenylamine (PTPAn) cathode, and KPF₆-based electrolyte. The PDIBs delivered a reversible capacity of 60 mA h g^–1 at a median discharge voltage of 3.23 V at 50 mA g^–1, with superior rate performance and long-term cycling stability over 500 cycles (capacity retention of 75.5%). Unlike the traditional dual-ion batteries, the operation mechanism of the PDIBs with PTPAn cathode is that the PF₆^– ions interacted with the nitrogen atom reversibly in the PTPAn cathode and the K⁺ ions were intercalated/deintercalated into/from the graphite anode during the charge/discharge process

Hierarchical Ni- and Co-based oxynitride nanoarrays with superior lithiophilicity for high-performance lithium metal anodes

Lithium metal has emerged as the most prospective candidate for the realization of improved battery systems. However, notorious Li dendrite formation and the huge volume effect during cycling critically impair the further practical deployment of Li metal batteries. Herein, we propose hierarchical Ni- and Co-based oxynitride (NiCoO2/CoO/Ni3N) nanoarrays with superior lithiophilicity on a three-dimensional nickel foam (NiCoON/NF) as a host for highly stable Li metal anodes. The uniform nitrogen-infused nanorod-on-nanosheet arrays present improved electrical conductivity and an increased concentration of active sites with oxygen vacancies to enhance the surface lithiophilicity, which effectively facilitates homogeneous Li nucleation/growth. Moreover, the hyperbranched structure can induce a homogeneous distribution of Li-ion flux, owing to the enlarged surface area, thereby providing sufficient space to store deposited lithium and relieve the volume expansion. Consequently, the NiCoON/NF host delivers a high Coulombic efficiency (98.4% over 600 cycles) at 1 mA cm-2 and an ultralong lifespan (> 2000 h) under a high capacity of 3 mAh cm-2. Remarkably, a Li@NiCoON/NF-LiFePO4 full battery also reveals impressive electrochemical performance. This work demonstrates new insights into safe rechargeable Li metal batteries

Carboxymethyl Chitosan‐Modified Zinc Anode for High‐Performance Zinc–Iodine Battery with Narrow Operating Voltage

Reasonable regulation of iodine redox has gradually shown potential as a desirable cathodic reaction in zinc‐based batteries, but suffers from poor cyclic reversibility caused by uncontrollable side reactions. Also, the irregular growth of dendrites and unavoidable occurrences of hydrogen evolution reaction in H2O‐rich environment have become permanent topics in anodic zinc. Herein, a cross‐linked gel based on carboxymethyl chitosan is proposed and serves as an artificial electrolyte interphase for zinc anode (marked as Zn‐CMCS). Such a coating formed by crosslinking among a monodentate carboxyl group, a hydroxyl, an amino, and Zn2+ from adding solution closely adheres on the surface of the zinc foil with toughness, ductility, and ideal electrochemical kinetics. Additionally, its homogenized surface charge distribution provides a “flexible” substrate for zinc plating/stripping, resulting in a flat real‐time interface. While introducing I−/I0 conversion by matching adsorptive activated carbon on carbon fiber cloth (AC‐CFC) as cathode, the internal space restricted by CMCS gel enables the assembled Zn‐CMCS/AC‐CFC battery to exhibit a greatly improved reversibility under long‐cycling condition within 28 000 cycles (measured for more than 2 years) in a narrow operating voltage range of 0.23 V

Tailoring grain boundary stability of zinc-titanium alloy for long-lasting aqueous zinc batteries

Abstract The detrimental parasitic reactions and uncontrolled deposition behavior derived from inherently unstable interface have largely impeded the practical application of aqueous zinc batteries. So far, tremendous efforts have been devoted to tailoring interfaces, while stabilization of grain boundaries has received less attention. Here, we demonstrate that preferential distribution of intermetallic compounds at grain boundaries via an alloying strategy can substantially suppress intergranular corrosion. In-depth morphology analysis reveals their thermodynamic stability, ensuring sustainable potency. Furthermore, the hybrid nucleation and growth mode resulting from reduced Gibbs free energy contributes to the spatially uniform distribution of Zn nuclei, promoting the dense Zn deposition. These integrated merits enable a high Zn reversibility of 99.85% for over 4000 cycles, steady charge-discharge at 10 mA cm−2, and impressive cyclability for roughly 3500 cycles in Zn-Ti//NH4V4O10 full cell. Notably, the multi-layer pouch cell of 34 mAh maintains stable cycling for 500 cycles. This work highlights a fundamental understanding of microstructure and motivates the precise tuning of grain boundary characteristics to achieve highly reversible Zn anodes

Electro-spraying/spinning: A novel battery manufacturing technology

Lithium-ion battery (LIB) industry seems to have met its bottle neck in cutting down producing costs even though much efforts have been put into building a complete industrial chain. Actually, manufacturing methods can greatly affect the cost of battery production. Up to now, lithium ion battery producers still adopt manufacturing methods with cumbersome sub-components preparing processes and costly assembling procedures, which will undoubtedly elevate the producing cost. Herein, we propose a novel approach to directly assemble battery components (cathode, anode and separator) in an integrated way using electro-spraying and electro-spinning technologies. More importantly, this novel battery manufacturing method can produce LIBs in large scale, and the products show excellent mechanical strength, flexibility, thermal stability and electrolyte wettability. Additionally, the performance of the as-prepaed LiFePO4||graphite full cell produced by this new method is comparable or even better than that produced by conventional manufacturing approach. In brief, this work provides a new promising technology to prepare LIBs with low cost and better performance

Atomic-Scale Control of Silicon Expansion Space as Ultrastable Battery Anodes

Development of electrode materials with high capability and long cycle life are central issues for lithium-ion batteries (LIBs). Here, we report an architecture of three-dimensional (3D) flexible silicon and graphene/carbon nanofibers (FSiGCNFs) with atomic-scale control of the expansion space as the binder-free anode for flexible LIBs. The FSiGCNFs with Si nanoparticles surrounded by accurate and controllable void spaces ensure excellent mechanical strength and afford sufficient space to overcome the damage caused by the volume expansion of Si nanoparticles during charge and discharge processes. This 3D porous structure possessing built-in void space between the Si and graphene/carbon matrix not only limits most solid-electrolyte interphase formation to the outer surface, instead of on the surface of individual NPs, and increases its stability but also achieves highly efficient channels for the fast transport of both electrons and lithium ions during cycling, thus offering outstanding electrochemical performance (2002 mAh g^–1 at a current density of 700 mA g^–1 over 1050 cycles corresponding to 3840 mAh g^–1 for silicon alone and 582 mAh g^–1 at the highest current density of 28 000 mA g^–1)