Carbonaceous materials have emerged as promising anode candidates for potassium‐ion batteries (PIBs) due to overwhelming advantages including cost‐effectiveness and wide availability of materials. However, further development in this realm is handicapped by the deficiency in their in‐target and large‐scale synthesis, as well as their low specific capacity and huge volume expansion. Herein the precise and scalable synthesis of N/S dual‐doped graphitic hollow architectures (NSG) via direct plasma enhanced chemical vapor deposition is reported. Thus‐fabricated NSG affording uniform nitrogen/sulfur co‐doping, possesses ample potassiophilic surface moieties, effective electron/ion‐transport pathways, and high structural stability, which bestow it with high rate capability (≈100 mAh g−1 at 20 A g−1) and a prolonged cycle life (a capacity retention rate of 90.2% at 5 A g−1 after 5000 cycles), important steps toward high‐performance K‐ion storage. The enhanced kinetics of the NSG anode are systematically probed by theoretical simulations combined with operando Raman spectroscopy, ex situ X‐ray photoelectron spectroscopy, and galvanostatic intermittent titration technique measurements. In further contexts, printed NSG electrodes with tunable mass loading (1.84, 3.64, and 5.65 mg cm−2) are realized to showcase high areal capacities. This study demonstrates the construction of a printable carbon‐based PIB anode, that holds great promise for next‐generation grid‐scale PIB applications.

Potassium-ion batteries (KIBs) have shown increasingly attractive potential for practical applications in terms of the resource enrichness and cost-effectiveness. [1][2][3] In comparison with the congener, lithium-ion battery (LIB), one specific merit of KIBs is that K + (3.6 Å) has smaller solvated radius in propylene carbonate electrolytes as compared to Li + (4.8 Å) and lower desolvation energy, which corresponds to higher diffusion kinetics and conductivity of ions. [4,5] In addition, the standard redox potential of K is similar to or even lower than that of Li in nonaqueous electrolyte, consequently guaranteeing advanced energy density. Nevertheless, one of the main challenges for KIBs lies in the much bigger radius of K + (1.38 Å) as compared to Li + (0.76 Å), making it difficult to insert/extract into/from the anodes. [4,6] This would inevitably lead to an irreversible distortion of the electrodes and hence incur the capacity attenuation upon long-term cycling. In this sense, it is a priority to design appropriate anode materials to advance the KIB technology.To date, there has been a plethora of material candidates attempted as anodes for KIBs, including carbonaceous materials, metal alloys, and transition metal oxides/sulfides/selenides/carbides. [2,7] Among these, carbon-based anodes have readily stimulated widespread interests due to its satisfying conductivity and wide availability. [8] Graphite, the commercial anode material for LIB, could also be used as anode for KIB because of their similar cell structure and working mechanism. [9] Despite the fact that graphite has excellent electrochemical activity benefiting from its low and stable voltage plateau, it still suffers from unsatisfactory capacity (with a theoretical value of 279 mAh g −1 ). Furthermore, inferior cycling stability and poor Coulombic efficiency also hinder the performance of graphite anodes for KIBs. [9,10] In this sense, designing innovative carbon architectures harnessing heteroatom doping, appropriate surface area, and sufficient active sites are highly desirable for boosting the performance of anodes. [11][12][13][14][15] In particular, the introduction of heteroatom dopants into carbon frameworks has been proven an effective way to modify the crystal structure and intrinsic electronic/ionic states, which is beneficial to enhancing the adsorption of K ions and boosting

The heteroatom co-doped carbonaceous anodes have readily attracted great attention in potassium-ion batteries (PIBs), owing to their augmented carbon interlayer distances and increased K + storage sites to induce enhanced capacity value. Nevertheless, the synergistic effect of dual-doped heteroatoms is still unclear and lacks systematic explorations. In addition, traditional synthetic routes are cumbersome with template removal step, which are normally deficient in product scalability. Herein, a generic protic-salt strategy is devised to realize sulfur-, phosphorus-or boron-nitrogen dual-doped carbon (SNC, PNC, or BNC) via varying the types of protic precursors (e.g., the acid). Throughout comprehensive instrumental probing and theoretical simulation, it is identified that the presence of B-N moiety can harvest high adsorption capability of K + and hence exhibit more obvious pseudocapacitance behavior than bare N-doped carbon counterpart. As a PIB anode, the BNC electrode displays an impressive reversible capacity (360.5 mAh g −1 at 0.1 A g −1 ) and cycle stability (125.4 mAh g −1 at 1 A g −1 after 3000 cycles). In situ/ex situ characterizations further reveal the origin of the excellent electrochemical properties of the BNC electrode. Such a tailorable protic-salt derived anode material offers new possibilities to advance PIB devices.

energy density. [3] Fortunately, the exploration of novel configurations of K-based energy storage systems is expected to provide key breakthroughs in overcoming performance bottlenecks. [4] An anode-free battery archi tecture tactfully eliminates active anode materials by pairing a fully preintercalated cathode with a bare anode current collector, thereby endowing the full-cell with increased energy density. [5] Pint et al. constructed an anode-free Na-metal battery using sodiated pyrite as the cathode and Al foils modified with a carbon nucleation layer as the anode current collector, achieving an energy density of ≈400 Wh kg −1 . [4a] Meanwhile, Luo et al. reported an anode-free porous Al||presodiated TiS 2 full-cell with increased energy density. [6] Recently, Mitlin et al. devised an innovative anode-free Na-metal battery comprising a Na 2 (Sb 2/6 Te 3/6 Vac 1/6 ) current collector and Na 3 V 2 (PO 4 ) 3 cathode, obtaining a capacity decay of only 0.23% per cycle. [7] Despite these achievements, anode-free K-metal batteries have rarely been explored.Besides possessing advantages over Cu in terms of cost and weight, Al foil can function as an anode current collector in anode-free K-metal batteries. [8] However, commercial Al current collectors are electrochemically potassiophobic and exhibit high nucleation resistance, inducing uneven electrochemical K deposition. [9] This results in poor reversibility during the plating/stripping process, which is reflected by a low Coulombic efficiency (CE). As anode-free K-metal batteries possess a finite K inventory in the cathode, the low CE might eventually result in capacity plunge and battery failure. [5,10] Therefore, it is of core significance to modulate the nucleation-growth behavior of K on an Al current collector through scalable and delicate surface modification. [11] Various conceptual models have been proposed to reveal the electrochemical growth behavior of metals that are complementary toward each other. [12] Recently, a film growth model was established to explain the growth of metals from a new perspective. [13] In this model, the electrochemical plating of K can be analogized as thin-film growth in vacuum and is governed by the surface energy of the substrate. [14] Based on this model, it is feasible to tune the surface energy of an Al current collector to ameliorate the nucleation-growth behavior Potassium (K)-metal batteries have emerged as a promising energy-storage device owing to abundant K resources. An anode-free architecture that bypasses the need for anode host materials can deliver an elevated energy density. However, the poor efficiency of K plating/stripping on potassiophobic anode current collectors results in rapid K inventory loss and a short cycle life. Herein, commercial Al foils are decorated with an ultrathin graphenemodified layer (Al@G) through roll-to-roll plasma-enhanced chemical vapor deposition. By harnessing strong adhesion (10.52 N m −1 ) and a high surface energy (66.6 mJ m −2 ), the designed Al@G structure ensures a highly...

Although graphite materials with desirable comprehensive properties dominate the anode market of commercial lithium‐ion batteries (LIBs), their low capacity during fast charging precludes further commercialization. In the present work, natural graphite (G) is reported not only to suffer from low capacity during fast charging, but also from charge failure after many charging cycles. Using different characterization techniques, severe graphite exfoliation, and continuously increasing solid electrolyte interphase (SEI) are demonstrated as reasons for the failure of G samples. An ultrathin artificial SEI is proposed, addressing these problems effectively and ensuring extremely stable operation of the graphite anode, with a capacity retention of ≈97.5% after 400 cycles at 1 C. Such an artificial SEI modification strategy provides a universal approach to tailoring and designing better anode materials for next‐generation LIBs with high energy densities.