Carbon nanofibers produced by electrospinning of polyacrylonitrile polymer and subsequent carbonization were tested as freestanding potassium-ion anodes. The effect of oxygen functionalization on K-ion carbon anode performance was tested for the first time via plasma oxidation of prepared carbon nanofibers. The produced materials exhibited exceptional cycling stability through the amorphous carbon structuring and one-dimensional architecture accommodating significant material expansion upon K intercalation, resulting in a stable capacity of 170 mAh g after 1900 cycles at 1C rate for N-rich carbon nanofibers. Excellent rate performance of 110 mAh g at 10C rate, as compared to 230 mAh g at C/10 rate, resulted from the K-ion surface storage mechanism and the increased K solid diffusion coefficient in carbon nanofibers as compared to graphite. Plasma oxidation treatment augmented surface storage of K by oxygen functionalities but increased material charge transfer resistance as compared to N-rich carbon fibers. Ex situ characterization revealed that the one-dimensional structure was maintained throughout cycling, despite the increase in graphitic interlattice spacing from 0.37 to 0.46 nm. The carbon nanofibers demonstrate great potential as an anode material for potassium-ion batteries with superior cycling stability and rate capability over previously reported carbon materials.

Herein, we report on the electrochemical performance of two-dimensional transition metal carbonitrides as novel promising electrode materials in K-ion batteries. Titanium carbonitride, TiCNT, was investigated in detail using electrochemical galvanostatic cycling at various current densities. X-ray diffraction and X-ray photoelectron spectroscopy were used to study the potassiation mechanism and its structural changes.

electrolyte, but were limited by significant safety concerns, such as thermal runaway, arising from the lithium metal anode and its tendency for dendrite formation. These dendrites develop and grow due to uneven lithium deposition caused by irregularities in the solid electrolyte interphase (SEI) passivation layer, which forms via electrolyte decomposition on the highly reactive lithium anode surface. Eventually, repeated cycling can result in an internal short circuit via puncturing of the separator by dendrites for cell failure and possible thermal runaway. Extensive research was conducted to mitigate these concerns, primarily by electrolyte manipulation to improve SEI uniformity or implementation of a polymer based solid-state electrolyte. However, this issue has still not been fully overcome even to this day, resulting in the alternative strategy of replacing the lithium anode with an intercalation-based storage material.The development of these "rocking chair" batteries began in the 1980s, where charging transfers lithium from cathode to anode and discharging reverses this process, with the first practical demonstrations by Scrosati. [2] Substantial progress came with the discoveries of the standard electrode materials: LiCoO 2 cathode by Goodenough and co-workers in 1981, [3] and graphite anode by Yazami and Touzain in 1983. [4] The first cell comprising a carbon anode and LiCoO 2 cathode was tested by Yoshino in 1983, which exhibited superior safety features as compared to lithium metal anode. [5] Optimization of the electrolyte came from replacing propylene carbonate (PC), which underwent a decomposition reaction with graphite due to cointercalation and exfoliation, to ethylene carbonate (EC)/ diethyl carbonate (DEC) mixtures. A schematic of this mature LIB is shown in Figure 1a. Sony commercialized the lithiumion battery (LIB) in 1991, where the new electrochemistry demonstrated advantages of higher energy density, longer life time, and no memory effect, as compared to the conventional nickel-cadmium and nickel-metal hydride secondary cells. Further progress and improvement in electrolyte, electrode microstructure, and cell manufacturing has led to a doubling of energy density for LIBs since their inception, almost 30 years later, despite their analogous operation mechanism. [6] Additionally, from their initial application for handheld electronics, LIBs are now seeing rapid utilization in vehicle electrification, with the global LIB capacity projected to double to 278 GWh per year Since their commercialization by Sony in 1991, graphite anodes in combination with various cathodes have enabled the widespread success of lithium-ion batteries (LIBs), providing over 10 billion rechargeable batteries to the global population. Next-generation nonaqueous alkali metal-ion batteries, namely sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs), are projected to utilize intercalation-based carbon anodes as well, due to their favorable electrochemical properties. While traditionally graphite anodes have d...

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The recycling of waste-tire rubber is of critical importance since the discarded tires pose serious environmental and health hazards to our society. Here, we report a new application for hard-carbon materials derived from waste-tires as anodes in potassium-ion batteries. The sustainable tire-derived carbons show good reversible potassium insertion at relatively high rates. Long-term stability tests exhibit capacities of 155 and 141 mAh g −1 for carbon pyrolyzed at 1100 • C and 1600 • C, respectively, after 200 cycles at current rate of C/2. This study provides an alternative solution for inexpensive and environmental benign potassium-ion battery anode materials.