Core/Double-Shell Type Gradient Ni-Rich LiNi_0.76Co_0.10Mn_0.14O₂ with High Capacity and Long Cycle Life for Lithium-Ion Batteries

A concentration-gradient Ni-rich LiNi_0.76Co_0.1Mn_0.14O₂ layered oxide cathode has been developed by firing a core/double-shell [Ni_0.9Co_0.1]_0.4[Ni_0.7Co_0.1Mn_0.2]_0.5[Ni_0.5Co_0.1Mn_0.4]_0.1(OH)₂ hydroxide precursor with LiOH·H₂O, where the Ni-rich interior (core) delivers high capacity and the Mn-rich exterior (shells) provides a protection layer to improve the cyclability and thermal stability for the Ni-rich oxide cathodes. The content of nickel and manganese, respectively, decreases and increases gradually from the center to the surface of each gradient sample particle, offering a high capacity with enhanced surface/structural stability and cyclability. The obtained concentration-gradient oxide cathode exhibits high-energy density with long cycle life in both half and full cells. With high-loading electrode half cells, the concentration-gradient sample delivers 3.3 mA h cm^–2 with 99% retention after 100 cycles. The material morphology, phase, and gradient structure are also maintained after cycling. The pouch-type full cells fabricated with a graphite anode delivers high capacity with 89% capacity retention after 500 cycles at C/3 rate

Long-Life Nickel-Rich Layered Oxide Cathodes with a Uniform Li₂ZrO₃ Surface Coating for Lithium-Ion Batteries

As nickel-rich layered oxide cathodes start to attract worldwide interest for the next-generation lithium-ion batteries, their long-term cyclability in full cells remains a challenge for electric vehicles. Here we report a long-life Ni-rich layered oxide cathode (LiNi_0.7Co_0.15Mn_0.15O₂) with a uniform surface coating of the cathode particles with Li₂ZrO₃. A pouch-type full cell fabricated with the Li₂ZrO₃-coated cathode and a graphite anode displays 73.3% capacity retention after 1500 cycles at a C/3 rate. The Li₂ZrO₃ coating has been optimized by a systematic study with different synthesis approaches, annealing temperatures, and coating amounts. The complex relationship among the coating conditions, uniformity, and morphology of the coating layer and their impacts on the electrochemical properties are discussed in detail

High Capacity O3-Type Na[Li_0.05(Ni_0.25Fe_0.25Mn_0.5)_0.95]O₂ Cathode for Sodium Ion Batteries

In this work we report Na­[Li_0.05(Ni_0.25Fe_0.25Mn_0.5)_0.95]­O₂ layered cathode materials that were synthesized via a coprecipitation method. The Na­[Li_0.05(Ni_0.25Fe_0.25Mn_0.5)_0.95]­O₂ electrode exhibited an exceptionally high capacity (180.1 mA h g^–1 at 0.1 C-rate) as well as excellent capacity retentions (0.2 C-rate: 89.6%, 0.5 C-rate: 92.1%) and rate capabilities at various C-rates (0.1 C-rate: 180.1 mA h g^–1, 1 C-rate: 130.9 mA h g^–1, 5 C-rate: 96.2 mA h g^–1), which were achieved due to the Li supporting structural stabilization by introduction into the transition metal layer. By contrast, the electrode performance of the lithium-free Na­[Ni_0.25Fe_0.25Mn_0.5]­O₂ cathode was inferior because of structural disintegration presumably resulting from Fe³⁺ migration from the transition metal layer to the Na layer during cycling. The long-term cycling using a full cell consisting of a Na­[Li_0.05(Ni_0.25Fe_0.25Mn_0.5)_0.95]­O₂ cathode was coupled with a hard carbon anode which exhibited promising cycling data including a 76% capacity retention over 200 cycles

Advanced Na[Ni_0.25Fe_0.5Mn_0.25]O₂/C–Fe₃O₄ Sodium-Ion Batteries Using EMS Electrolyte for Energy Storage

While much research effort has been devoted to the development of advanced lithium-ion batteries for renewal energy storage applications, the sodium-ion battery is also of considerable interest because sodium is one of the most abundant elements in the Earth’s crust. In this work, we report a sodium-ion battery based on a carbon-coated Fe₃O₄ anode, Na­[Ni_0.25Fe_0.5Mn_0.25]­O₂ layered cathode, and NaClO₄ in fluoroethylene carbonate and ethyl methanesulfonate electrolyte. This unique battery system combines an intercalation cathode and a conversion anode, resulting in high capacity, high rate capability, thermal stability, and much improved cycle life. This performance suggests that our sodium-ion system is potentially promising power sources for promoting the substantial use of low-cost energy storage systems in the near future

High Electrochemical Performances of Microsphere C‑TiO₂ Anode for Sodium-Ion Battery

High-power, long-life carbon-coated TiO₂ microsphere electrodes were synthesized by a hydrothermal method for sodium ion batteries, and the electrochemical properties were evaluated as a function of carbon content. The carbon coating, introduced by sucrose addition, had an effect of suppressing the growth of the TiO₂ primary crystallites during calcination. The carbon coated TiO₂ (sucrose 20 wt % coated) electrode exhibited excellent cycle retention during 50 cycles (100%) and superior rate capability up to a 30 <i>C</i> rate at room temperature. This cell delivered a high discharge capacity of 155 mAh g_composite^–1 at 0.1 <i>C</i>, 149 mAh g_composite^–1 at 1 <i>C</i>, and 82.7 mAh g_composite^–1 at a 10 <i>C</i> rate, respectively

Surfactant-Assisted Synthesis of Fe₂O₃ Nanoparticles and F‑Doped Carbon Modification toward an Improved Fe₃O₄@CF_<i>x</i>/LiNi_0.5Mn_1.5O₄ Battery

A simple surfactant-assisted reflux method was used in this study for the synthesis of cocklebur-shaped Fe₂O₃ nanoparticles (NPs). With this strategy, a series of nanostructured Fe₂O₃ NPs with a size distribution ranging from 20 to 120 nm and a tunable surface area were readily controlled by varying reflux temperature and the type of surfactant. Surfactants such as cetyltrimethylammonium bromide (CTAB), polyvinylpyrrolidone (PVP), poly­(ethylene glycol)-<i>block</i>-poly­(propylene glycol)-<i>block</i>-poly­(ethylene glycol) (F127) and sodium dodecyl benzenesulfonate (SDBS) were used to achieve large-scale synthesis of uniform Fe₂O₃ NPs with a relatively low cost. A new composite of Fe₃O₄@CF_<i>x</i> was prepared by coating the primary Fe₂O₃ NPs with a layer of F-doped carbon (CF_<i>x</i>) with a one-step carbonization process. The Fe₃O₄@CF_<i>x</i> composite was utilized as the anode in a lithium ion battery and exhibited a high reversible capacity of 900 mAh g^–1 at a current density of 100 mA g^–1 over 100 cycles with 95% capacity retention. In addition, a new Fe₃O₄@CF_<i>x</i>/LiNi_0.5Mn_1.5O₄ battery with a high energy density of 371 Wh kg^–1 (vs cathode) was successfully assembled, and more than 300 cycles were easily completed with 66.8% capacity retention at 100 mA g^–1. Even cycled at the high temperature of 45 °C, this full cell also exhibited a relatively high capacity of 91.6 mAh g^–1 (vs cathode) at 100 mA g^–1 and retained 54.6% of its reversible capacity over 50 cycles. Introducing CF_<i>x</i> chemicals to modify metal oxide anodes and/or any other cathode is of great interest for advanced energy storage and conversion devices

Highly Cyclable Lithium–Sulfur Batteries with a Dual-Type Sulfur Cathode and a Lithiated Si/SiO_<i>x</i> Nanosphere Anode

Lithium–sulfur batteries could become an excellent alternative to replace the currently used lithium-ion batteries due to their higher energy density and lower production cost; however, commercialization of lithium–sulfur batteries has so far been limited due to the cyclability problems associated with both the sulfur cathode and the lithium–metal anode. Herein, we demonstrate a highly reliable lithium–sulfur battery showing cycle performance comparable to that of lithium-ion batteries; our design uses a highly reversible dual-type sulfur cathode (solid sulfur electrode and polysulfide catholyte) and a lithiated Si/SiO_<i>x</i> nanosphere anode. Our lithium–sulfur cell shows superior battery performance in terms of high specific capacity, excellent charge–discharge efficiency, and remarkable cycle life, delivering a specific capacity of ∼750 mAh g^–1 over 500 cycles (85% of the initial capacity). These promising behaviors may arise from a synergistic effect of the enhanced electrochemical performance of the newly designed anode and the optimized layout of the cathode