A look at the research and development of sodium-ion batteries is presented. The use of organic compounds as electrode materials is one of the topics discussed.
Li‐ion battery commercialized by Sony in 1991 has the highest energy‐density among practical rechargeable batteries and is widely used in electronic devices, electric vehicles, and stationary energy ...storage system in the world. Moreover, the battery market is rapidly growing in the world and further fast‐growing is expected. With expansion of the demand and applications, price of lithium and cobalt resources is increasing. We are, therefore, motivated to study Na‐ and K‐ion batteries for stationary energy storage system because of much abundant Na and K resources and the wide distribution in the world. In this account, we review developments of Na‐ and K‐ion batteries with mainly introducing our previous and present researches in comparison to that of Li‐ion battery.
Li‐ion battery commercialized by Sony in 1991 has the highest energy‐density among rechargeable batteries and is widely used in the world. With expansion of the applications and rapid growing of the battery market, price of lithium and cobalt resources is increasing. In this account, we review developments of Na‐ and K‐ion batteries, consisting of much abundant Na and K, with mainly introducing our previous and present researches in comparison to that of Li‐ion battery.
High-capacity Ni-rich layered oxides are promising cathode materials for secondary lithium-based battery systems. However, their structural instability detrimentally affects the battery performance ...during cell cycling. Here, we report an Al/Zr co-doped single-crystalline LiNi
Co
Mn
O
(SNCM) cathode material to circumvent the instability issue. We found that soluble Al ions are adequately incorporated in the SNCM lattice while the less soluble Zr ions are prone to aggregate in the outer SNCM surface layer. The synergistic effect of Al/Zr co-doping in SNCM lattice improve the Li-ion mobility, relief the internal strain, and suppress the Li/Ni cation mixing upon cycling at high cut-off voltage. These features improve the cathode rate capability and structural stabilization during prolonged cell cycling. In particular, the Zr-rich surface enables the formation of stable cathode-electrolyte interphase, which prevent SNCM from unwanted reactions with the non-aqueous fluorinated liquid electrolyte solution and avoid Ni dissolution. To prove the practical application of the Al/Zr co-doped SNCM, we assembled a 10.8 Ah pouch cell (using a 100 μm thick Li metal anode) capable of delivering initial specific energy of 504.5 Wh kg
at 0.1 C and 25 °C.
Sodium-ion batteries (SIBs) are among the most promising candidates for large-scale electrical energy storage devices owing to the low cost, abundance, and widespread of sodium resources. However, ...finding a suitable anode material is a critical necessity to uphold the commercialisation of SIBs. Herein, we report a facile synthesis process to prepare hard carbons derived from date palm biomass consisting of direct pyrolysis of seeds or pulp at different heat treatment temperatures in the range between 800 and 1400 °C. The electrochemical performances of the prepared hard carbons were investigated in SIBs and exhibited high reversible capacity of 300 mAh g−1 and promising initial coulombic efficiency (ICE) of 88.4%, which is the highest ICE reported for hard carbon materials to date. This work is the first to report a successful implementation of date palm as precursor to prepare low cost and high performance hard carbon anode materials for SIBs.
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Considering the natural abundance and low cost of sodium resources, sodium‐ion batteries (SIBs) have received much attention for large‐scale electrochemical energy storage. However, smart structure ...design strategies and good mechanistic understanding are required to enable advanced SIBs with high energy density. In recent years, the exploration of advanced cathode, anode, and electrolyte materials, as well as advanced diagnostics have been extensively carried out. This review mainly focuses on the challenging problems for the attractive battery materials (i.e., cathode, anode, and electrolytes) and summarizes the latest strategies to improve their electrochemical performance as well as presenting recent progress in operando diagnostics to disclose the physics behind the electrochemical performance and to provide guidance and approaches to design and synthesize advanced battery materials. Outlook and perspectives on the future research to build better SIBs are also provided.
Room temperature sodium‐ion batteries show great promise for large scale electrochemical energy storage application because of the low cost and large abundance of sodium resource. The progress and main challenges regarding the development of electrode, electrolytes, and advanced diagnostics are summarized with the aim of achieving a high energy density of over 400 Wh kg−1 on the cell level.
For a nonaqueous sodium-ion battery (NIB), phosphorus materials have been studied as the highest-capacity negative electrodes. However, the large volume change of phosphorus upon cycling at low ...voltage causes the formation of new active surfaces and potentially results in electrolyte decomposition at the active surface, which remains one of the major limiting factors for the long cycling life of batteries. In this present study, powerful surface characterization techniques are combined for investigation on the electrode/electrolyte interface of the black phosphorus electrodes with polyacrylate binder to understand the formation of a solid electrolyte interphase (SEI) in alkyl carbonate ester and its evolution during cycling. The hard X-ray photoelectron spectroscopy (HAXPES) analysis suggests that SEI (passive film) consists of mainly inorganic species, which originate from decomposition of electrolyte solvents and additives. The thicker surface layer is formed during cycling in the additive-free electrolyte, compared to that in the electrolyte with fluoroethylene carbonate (FEC) or vinylene carbonate (VC) additive. The HAXPES and time-of-flight secondary ion mass spectroscopy (TOF-SIMS) studies further reveal accumulation of organic carbonate species near the surface and inorganic salt decomposition species. These findings open paths for further improvement for the cyclability of phosphorus electrodes for high-energy NIBs.
Electrochemical performance of the red phosphorus electrode was examined in ionic-liquid electrolyte, 0.25 mol dm−3 sodium bisfluorosulfonylamide (NaFSA) dissolved ...N-methyl-N-propylpyridinium-bisfluorosulfonylamide (MPPFSA), at room temperature. We compared its electrochemical performance to conventional EC/PC/DEC, EC/DEC, and PC solutions containing 1 mol dm−3 NaPF6. The electrode in NaFSA/MPPFSA demonstrated a reversible capacity of 1480 mAh g−1 and excellent capacity retention of 93% over 80 cycles, which is much better than those in the conventional electrolytes. The difference in capacity retention for the electrolytes correlates to the different solid electrolyte interphase (SEI) layer formed on the phosphorus electrode. To understand the SEI formation in NaFSA/MPPFSA and its evolution during cycling, we investigate the surface layer of the red phosphorus electrodes with hard X-ray photoelectron spectroscopy (HAXPES) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). A detailed analysis of HAXPES spectra demonstrates that SEI layer consists of major inorganic and minor organic species, originating from decomposition of MPP+ and FSA−. Homogenous surface layer is formed during the first cycle in NaFSA/MPPFSA while in alkyl carbonate ester electrolytes, continuous growth of surface film up to the 20th cycle is observed. Possibility of red phosphorous electrode for battery applications with pure ionic liquid is discussed.
•Na storage performance of red P in MPPFSA ionic liquid electrolyte at 25 °C.•High-reversible capacity (1480 mAh g−1) and excellent-capacity retention of red P in NaFSA/MPPFSA electrolyte.•NaFSA and MPPFSA ionic liquid for improving the cyclability of red P electrodes.•SEI layer studied by photoelectron and secondary-ion mass spectroscopies.
Nonuniform Li deposition causes dendrites and low Coulombic efficiency (CE), seriously hindering the practical applications of Li metal. Herein, we developed an artificial solid-state interphase ...(SEI) with planar polycyclic aromatic hydrocarbons (PAHs) on the surface of Li metal anodes by a facile in situ formation technology. The resultant dihydroxyviolanthron (DHV) layers serve as the protective layer to stabilize the SEI. In addition, the oxygen-containing functional groups in the soft and conformal SEI film can regulate the diffusion and transport of Li ions to homogenize the deposition of Li metal. The artificial SEI significantly improves the CEs and shows superior cyclability of over 1000 h at 4 mAh cm–2. The LiFePO4/Li cell (2.8 mAh cm–2) enables a long cyclability for 300 cycles and high CEs of 99.8%. This work offers a new strategy to inhibit Li dendrite growth and enlightens the design on stable SEI for metal anodes.
Electrochemical sodium insertion for hard carbon is examined in a cyclic alkylene carbonate based solution containing a NaClO4 or NaPF6 salt with a fluoroethylene carbonate (FEC) additive to study ...electrolyte dependency for sodium‐ion batteries. NaPF6‐based electrolytes provide superior reversibility and cyclability of sodium insertion into hard carbon compared with NaClO4‐based ones. The FEC‐derived passivation film improves capacity retention because of better passivation with a thinner surface layer, as revealed by hard and soft X‐ray photoelectron spectroscopy (PES). The use of both the NaPF6 salt and FEC additive results in a synergetic effect on passivation for the hard‐carbon electrode, leading to enhanced cycle performance. Hard‐carbon electrodes with polyvinylidene difluoride binder in propylene carbonate based electrolytes containing NaPF6 and FEC demonstrate excellent capacity retention with a reversible capacity of about 250 mAh g−1. The difference in capacity retention for the electrolytes is expected to originate as a consequence of the difference in the surface interphase layer formed on the hard‐carbon electrodes. Surface analyses with PES and time‐of‐flight secondary ion mass spectrometry reveal differences in surface and passivation chemistry which depend on the salts, solvents, and FEC additives used for the hard‐carbon negative electrodes.
Developing a thin skin: The electrochemical properties of hard‐carbon electrodes in sodium cells are examined. NaPF6‐based electrolytes provide superior reversibility and cyclability of sodium insertion into hard carbon compared with NaClO4‐based ones (see figure). The fluoroethylene carbonate (FEC) additive further improves capacity retention because of better passivation with a thinner surface layer. PVdF=polyvinylidene difluoride.
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