Jongsoon Kim

Maricite NaFePO₄can function as an excellent cathode material for Na ion batteries, an unexpected result since it has been regarded as an electrochemically inactive electrode for rechargeable batteries.

Zinc-ion batteries are emerging as next-generation rechargeable batteries that can operate in aqueous electrolytes. We first examine the feasibility of open-structured VO2(B) as a Zn2+ intercalation host. A bond-valence sum energy map predicts that four Zn2+-ion sites (ZnC, ZnA1, ZnA2, and ZnC′) can exist in the structure. Using first-principles calculations, we verified that 0.5 mol of Zn2+ ions can be reversibly (de)intercalated with an average voltage of ∼0.61 V (vs Zn2+/Zn), which is compara

Abstract Conversion‐based electrode materials for rechargeable sodium batteries (RSBs) have received considerable attention because of their potentially higher energy densities than those of conventional intercalation‐based electrode materials. This would overcome generally lower energy densities of RSBs than those of lithium‐ion batteries. However, they often suffer from large volume changes, sluggish Na‐ion kinetics, and large overpotential in their reaction. Intensive research has thus focuse

We report the Mn based olivine electrode material with high power and energy. Easier and more frequent nucleation by Fe and Co in Mn-based olivines significantly enhanced the rate capability as evidenced by the electrochemical results.

The power capability of the NASICON-type Li3V2(PO4)3 electrode is greatly improved by coating with PEDOT, that is, poly(3,4-ethylenedioxythiophene), a conducting polymer. The Li3V2(PO4)3/PEDOT electrode delivers more than 90% of its theoretical capacity (133 mAh g−1) at a 10 C rate and 97% of this capacity is retained at this rate after 100 cycles. This remarkable power and cycle stability achieved by a simple coating process makes this 4 V-class electrode one of the most promising electrode can

Na7V3(P2O7)4 is capable of exhibiting 4.13 V of the redox potential as a cathode material for Na ion batteires, as revealed by the structural and electrochemical characterizations from first-principles calculations and experiments. The cyclability of Na7V3(P2O7)4 is respectably stable (75% retention after 600 cycles), which is attributed to the low volume change (1%) during cycling. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Suc

Abstract Na/FeS x batteries have remarkable potential applicability due to their high theoretical capacity and cost‐effectiveness. However, realization of high power‐capability and long‐term cyclability remains a major challenge. Herein, ultrafine Fe 7 S 8 @C nanocrystals (NCs) as a promising anode material for a Na–ion battery that addresses the above two issues simultaneously is reported. An Fe 7 S 8 core with quantum size (≈10 nm) overcomes the kinetic and thermodynamic constraints of the Na‐

Here, we introduce Na 3 V(PO 3 ) 3 N as a novel 4V-class and zero-strain cathode material for Na-ion batteries. Structural analysis based on a combination of neutron and X-ray diffraction (XRD) reveals that the Na 3 V(PO 3 ) 3 N crystal contains three-dimensional channels that are suitable for facile Na diffusion. The Na (de)intercalation is observed to occur at ∼4 V vs Na/Na + in the Na cell via the V 3+ /V 4+ redox reaction with ∼67% retention of the initial capacity after over 3000 cycles. Th

A novel Na-pillared LiFePO4 with an alluaudite structure is reported and its structure is investigated. The alluaudite-LiFePO4 allowed fast lithium diffusion with stable electrochemical cycling in lithium batteries. ∼0.8 Li+ could be extracted and reinserted reversibly for extended cycles via one-phase reaction in contrast to the well-known two-phase reaction in olivine-LiFePO4.

Abstract The practical application of lithium–sulfur batteries (LSBs) is limited by the shuttle effect of lithium polysulfides (LiPSs), large volume expansion, and sluggish conversion kinetics of sulfur. Herein, the crystallinity regulation of Ni x Fe y alloy anchored on oxidized carbon nanotube/nitrogen‐doped graphene (Ni x Fe y @OCNT/NG) for application of a functional separator into LSBs is demonstrated. A low crystalline Ni x Fe y @OCNT/NG (LC‐Ni x Fe y @OCNT/NG) modified polypropylene separ

Here we demonstrate that the electrochemical properties of Mn based olivine cathode materials can be significantly improved by small amount of co-dopants, Fe and Mg. While nucleation and growth are important in determining the kinetics of a two-phase reaction based olivine electrode, the presence of Fe and Mg in LiMnPO(4) framework notably enhances the power capability of a LiMnPO(4) electrode providing multiple nucleation sites. The electrochemical activity of an Fe-Mg co-doped Mn olivine catho

Abstract In this work, rhombohedral KTi 2 (PO 4 ) 3 is introduced to investigate the related theoretical, structural, and electrochemical properties in K cells. The suggested KTi 2 (PO 4 ) 3 modified by electro‐conducting carbon brings about a flat voltage profile at ≈1.6 V, providing a large capacity of 126 mAh (g‐phosphate) −1 , corresponding to 98.5% of the theoretical capacity, with 89% capacity retention for 500 cycles. Structural analyses using electrochemical performance measurements, fir

We introduce Na3V(PO4)2 as a new cathode material for Na-ion batteries for the first time. The structure of Na3V(PO4)2 was determined using X-ray diffraction and Rietveld refinement, and its high water stability was clearly demonstrated. The redox potential of Na3V(PO4)2 (∼3.5 V vs Na/Na+) was shown to be sufficiently high to prevent the side reaction with water (Na extraction and water insertion), ensuring its water stability in ambient air. Na3V(PO4)2 also exhibited outstanding power capabilit

A novel, Na-pillared LiMnPO₄ with an alluaudite structure that allows fast lithium diffusion with stable electrochemical cycling as a cathode in lithium batteries.