Carbon Composite Anodes with Tunable Microstructures for Potassium‐Ion Batteries

Abstract

Among the post‐lithium battery technologies, potassium‐ion batteries are promising for cost‐effective large‐scale energy storage, as potash is an abundant resource. However, a major challenge is to understand the structure‐performance relationships of carbon anodes for potassium‐ion storage. In this study, we have designed a variety of carbon composite materials from 100 % graphite to 100 % soft carbon and in between, with tunable structural features to fundamentally understand the roles of different carbon structural features in potassium ion insertion. We have found that the graphite‐soft carbon composites (G‐SC) show a high charge capacity of 280.2 mAh g−1 with an increased initial coulombic efficiency, representing the best reversibility among different carbon composites. Electrochemical impedance spectroscopy, cyclic voltammetry, and ex‐situ structural characterizations have been applied to substantiate that the presence of soft carbon in G‐SC inhibits the solid electrolyte interface layer formation and provides structural protection to the graphitic layers.

Defects in Hard Carbon: Where Are They Located and How Does the Location Affect Alkaline Metal Storage?

“…[1,62,64] Experimental XPS measurements commonly identify an oxygen content of ≈4% in HC, soft carbon, and composite carbon anodes for LIBs, NIBs, and KIBs. [66,67] Here, we consider four oxygen defects: single substitutional oxygen defect (O C ), oxygen substitutional defect and carbon vacancy (O C V C ), double oxygen substitutional defect (2O C ), and triple oxygen substitutional defect (3O C ). The O C and 2O C defects are purely substitutional in nature, whereas the O C V C defect includes a carbon vacancy.…”

“…[33,65,[76][77][78][79] For KIBs, the graphitic stacks' interlayer distances accessible to Na + and Li + storage can be inaccessible, with greater interlayer distances required. [33,61,66,80] Previously, we have studied, in isolation, basal plane defect adsorption, and intercalation in planar graphitic pores with varying interlayer distances (c) as guided by experimental HC characterization. [33,34] From these studies, we showed that metal adsorption is greatly enhanced at defect sites, [34] and that especially the sodium and potassium intercalation is heavily dependent on c, with potassium showing energetically favorable intercalation energies (i.e., negative binding energies) first at c > 3.85 Å, and sodium at c > 3.49 Å.…”

Perspective on Carbon Anode Materials for K+ Storage: Balancing the Intercalation‐Controlled and Surface‐Driven Behavior

“…Thus, a high ICE of 67.3%, reversible capacities of 280.2 mAh g −1 and a plateau‐dominated profile were obtained with the graphite‐soft carbon composite. [ 111 ] Meanwhile, compositing graphite with the hard carbon is also effective. By coating amorphous N‐doped carbon nanosheets on multilayer graphite (random orientations of the flake graphene), the resulting composite exhibits a flat discharge plateau from graphite and enhanced cyclic stability (215.7 mAh g −1 after 1000 cycles at 0.2 A g −1 ) and ICE (from uncoated graphite of 43.43% to 61.83%).…”

Strategies for High Energy Density Dual‐Ion Batteries Using Carbon‐Based Cathodes

“…[1] A greener CO 2 footprint for batteries will inevitably be a prerequisite in the near future to reach truly net-zero target commitments. [8,9] Here, new emerging battery technologies, including sodium-ion batteries, [10][11][12][13][14] potassium-ion batteries, [15,16] multivalent ion batteries, [17] and dual-ion batteries (DIBs), are regarded as more sustainable alternatives to LIBs.Among these alternatives, the advantages of DIBs (some common to the other battery chemistries) are: 1) eliminating lithium and critical elements such as nickel and cobalt thus removing the elements scarcity; 2) high working voltage and fast-charging (e.g., dual-graphite DIBs can reach a high power density of 8.66 kW kg À1 and a high energy density of 227 Wh kg À1 ); [18] and 3) sodium/potassium-based DIBs offer considerable opportunities due to the abundance of sodium reserves (2.7 wt %/28 400 mg kg À1 earth's crust; 11 000 mg L À1 seawater) and potassium reserves (2.4 wt%/26 000 mg kg À1 earth's crust; 380 mg L À1 seawater). [19] These merits allow DIBs to power small electric vehicles and large-scale stationary ("grid") energy storage.Cation-anion DIBs consist of Li-, [20] K-, [19,[21][22][23] Na-, [24] Mg-, [25] Ca-, [26] Al-, [27,28] and Zn-based [29,30] DIBs.…”

“…[1] A greener CO 2 footprint for batteries will inevitably be a prerequisite in the near future to reach truly net-zero target commitments. [8,9] Here, new emerging battery technologies, including sodium-ion batteries, [10][11][12][13][14] potassium-ion batteries, [15,16] multivalent ion batteries, [17] and dual-ion batteries (DIBs), are regarded as more sustainable alternatives to LIBs.…”