Progress in electrode materials for the industrialization of sodium-ion batteries

Lithium-ion batteries (LIBs) have become the preferred battery system for portable electronic devices and transportation equipment due to their high specific energy, good cycling performance, low self-discharge, and absence of memory effect. However, excessively low ambient temperatures will seriously affect the performance of LIBs, which are almost incapable of discharging at −40~−60 °C. There are many factors affecting the low-temperature performance of LIBs, and one of the most important is the electrode material. Therefore, there is an urgent need to develop electrode materials or modify existing materials in order to obtain excellent low-temperature LIB performance. A carbon-based anode is one candidate for use in LIBs. In recent years, it has been found that the diffusion coefficient of lithium ion in graphite anodes decreases more obviously at low temperatures, which is an important factor limiting its low-temperature performance. However, the structure of amorphous carbon materials is complex; they have good ionic diffusion properties, and their grain size, specific surface area, layer spacing, structural defects, surface functional groups, and doping elements may have a greater impact on their low-temperature performance. In this work, the low-temperature performance of LIBs was achieved by modifying the carbon-based material from the perspectives of electronic modulation and structural engineering.

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Electronic Modulation and Structural Engineering of Carbon-Based Anodes for Low-Temperature Lithium-Ion Batteries: A Review

New insights into the critical role of inactive element substitution in improving the rate performance of sodium oxide cathode material

Branded with low cost and a high degree of safety, with an ambitious aim of substituting lithium‐ion batteries in many fields, sodium‐ion batteries have received fervid attention in recent years after being dormant for decades. Layered materials are a major focus of study owing to the extensive experience already gained in lithium‐ion batteries, and the pursuit of a Mn‐rich composition is critical to reduce the cost while retaining the performance. This review provides a timely update of the recent progress of Mn‐rich layered materials for sodium‐ion batteries based on the understandings of the phase forming principles, structure transformation upon cycling and charge compensation mechanisms and discusses potential ambiguities in the pursuit of high‐performance materials.

Recent Advances in Mn‐Rich Layered Materials for Sodium‐Ion Batteries

Layered oxide cathodes for sodium-ion batteries: microstructure design, local chemistry and structural unit

Interlocking Biphasic Chemistry for High-Voltage P2/O3 Sodium Layered Oxide Cathode

O3-NaNi0.25Fe0.5Mn0.25O2 layered oxide is considered one of the most promising cathode candidates for sodium-ion batteries because of its advantages, such as its large capacity and low cost. However, the practical application of this material is limited by its poor cyclic stability and insufficient rate capability. Here, a strategy to substitute the Fe3+ in NaNi0.25Fe0.5Mn0.25O2 with Al3+ is adopted to address these issues. The substitution of Fe3+ with Al3+ enhances the framework stability and phase transition reversibility of the parent NaNi0.25Fe0.5Mn0.25O2 material by forming a stronger TM-O bond, which improves the cycling stability. Moreover, partial Al3+ substitution increases the interslab distance, providing a spacious path for Na+ diffusion and resulting in fast diffusion kinetics, which lead to improved rate capability. Consequently, the target NaNi0.25Fe0.5-xAlxMn0.25O2 sample with optimal x = 0.045 exhibits a remarkable electrochemical performance in a Na-ion cell with a large reversible capacity of 131.7 mA h g-1, a stable retention of approximately 81.6% after cycling at 1C for 100 cycles, and a rate performance of 81.3 mA h g-1 at 10C. This method might pave the way for novel means of improving the electrochemical properties of layered transitional-metal oxides and provide insightful guidance for the design of low-cost cathode materials.

Low-Cost Al-Doped Layered Cathodes with Improved Electrochemical Performance for Rechargeable Sodium-Ion Batteries.

Elucidation of the sodium kinetics in layered P-type oxide cathodes

Lithium-ion batteries are widely used in electric vehicles and smart grids to facilitate fast and stable energy storage at different temperatures. However, the decreased Li+ diffusion and poor electronic conductivity of commercial cathode materials inevitably lead to irreversible energy degradation at low temperature. Herein, we tame the relationship between diffusion and temperature of spinel LiNi0.5Mn1.5O4 cathode by incorporating Co element into transition-metal sites. The Co element into the LiNi0.5Mn1.5O4 lattice effectively improves the diffusion properties of lithium ions, enhances its electronic conductivity, and prevents the dissolution of Mn. Therefore, LiNi0.4Co0.1Mn1.5O4 could deliver a capacity retention of 93.89% at 1 C after 200 cycles at 25 °C. Even at −20 °C, it delivers 88.43% of its room-temperature capacity. Moreover, the assembled LiNi0.4Co0.1Mn1.5O4/graphite and LiNi0.4Co0.1Mn1.5O4/Li4Ti5O12 full cells both show a capacity retention of 98.03 and 86.61% at 1 C after 100 cycles, respectively. In particular, the LiNi0.4Co0.1Mn1.5O4/Li4Ti5O12 full battery still exhibits a discharge capacity of 116.9 mA h g–1 at −20 °C, reaching 90.24% of its room-temperature capacity. These results not only pave the way for improving the electrochemical performance of 5 V-based cathode materials but also provide insightful guidance for their commercial applications at low temperature. 

Cobalt-Doped Spinel Cathode for High-Power Lithium-Ion Batteries Toward Expanded Low-Temperature Applications

O3-type layered oxides with high initial sodium content are promising cathode candidates for Na-ion batteries. However, affected by the undesired transition metal slab sliding and reaction with H2O/CO2, their further application is typically hindered by unsatisfactory cycling stability upon charging to high voltage and poor storage stability under humid air. Herein, we demonstrate a Fe/Ti cosubstitution strategy to simultaneously enhance the electrochemical performance and storage stability of pristine O3-NaNi0.5Mn0.5O2 cathode material, via employing high redox potential and inactive stabilized dopants. The resultant Fe/Ti cosubstituted Na0.95Ni0.40Fe0.15Mn0.3Ti0.15O2 undergoes highly reversible O3-P3-OP2 phase transitions with a small cell volume change of 2.8%, instead of complex O3-O'3-P3-P'3-P3'-O1 phase transitions in NaNi0.5Mn0.5O2. Consequently, the cathode displays a high specific capacity of 161.6 mAh g-1 with an average working voltage of 3.28 V and 81.8% capacity retention after 200 cycles at 5C. Furthermore, the cathode material remains very stable after exposure to air for 7 days and even after soaking in water for 1 h, owing to the prohibition of sodium losing by elevating redox potential and contracting sodium layer spacing. This work proposes an effective method to enhance the electrochemical performance and storage stability of O3-type layered oxide cathodes and promises advancing Na-ion batteries toward large-scale industrialization.

Duo Si

Papers

Interlocking Biphasic Chemistry for High-Voltage P2/O3 Sodium Layered Oxide Cathode

Low-Cost Al-Doped Layered Cathodes with Improved Electrochemical Performance for Rechargeable Sodium-Ion Batteries.

Elucidation of the sodium kinetics in layered P-type oxide cathodes

Cobalt-Doped Spinel Cathode for High-Power Lithium-Ion Batteries Toward Expanded Low-Temperature Applications

O3-Type Na0.95Ni0.40Fe0.15Mn0.3Ti0.15O2 Cathode Materials with Enhanced Storage Stability for High-Energy Na-Ion Batteries.