Self-Passivation of a LiNiO₂ Cathode for a Lithium-Ion Battery through Zr Doping

A self-passivating Li2ZrO3 layer with a thickness of 5–10 nm, which uniformly encapsulates the surfaces of LiNiO2 cathode particles, is spontaneously formed by introducing excess Zr (1.4 atom %). A thin layer of Li2ZrO3 on the surface is converted into a stable impedance-lowering solid–electrolyte interphase layer during subsequent cycles. The Zr-doped LiNiO2 cathode with an initial discharge capacity of 233 mA·h·g–1 exhibited significantly improved capacity retention (86% after 100 cycles) and thermal stability, compared to the undoped LiNiO2. While the spontaneously formed Zr-rich coating layer provides surface protection, the Zr ions in the LiNiO2 lattice delay the detrimental phase transition occurring in the deeply charged state of LiNiO2 and partially suppress the anisotropic strain emerging from the phase transition. Further optimization of the proposed simultaneous coating and doping strategy can mitigate the inherent structural instability of the LiNiO2 cathode, making it a promising high-energy-density cathode for electric vehicles

High-Energy-Density Li-Ion Battery Reaching Full Charge in 12 min

The continuous expansion of the electric vehicle (EV) market is driving the demand for high-energy-density batteries using Ni-rich cathodes. However, the operation of Ni-rich cathodes under extreme-fast-charging (XFC) conditions compromises their structural integrity, resulting in rapid capacity fading; realizing Ni-rich cathodes operable under XFC conditions while maximizing energy density and long-term cycling performance is challenging. This study introduces a Li­[Ni0.92Co0.06Al0.01Nb0.01]­O2 (Nb-NCA93) cathode with a high energy density of 869 Wh kg–1. The presence of Nb in the Nb-NCA93 cathode induces the grain refinement of its secondary particles, alleviating internal stress and preventing heterogeneity of Li concentration during cycling. A resulting full-cell reaches full charge within 12 min and retains 85.3% of its initial capacity after 1000 cycles (cycled at full depth of discharge). In addition, the Nb-NCA93 cathode generates limited heat under XFC conditions due to its refined microstructure

Beyond Doping and Coating: Prospective Strategies for Stable High-Capacity Layered Ni-Rich Cathodes

This Perspective discusses the prospective strategies for overcoming the stability and capacity trade-off associated with increased Ni content in layered Ni-rich Li­[NixCoyMnz]­O2 (NCM) and Li­[NixCoyAlz]­O2 (NCA) cathodes. The Ni-rich NCM and NCA cathodes have largely replaced the LiCoO2 cathodes in commercial batteries because of their lower cost, higher energy density, good rate capability, and reliability that has been extensively field-tested. Nevertheless, they suffer from microcrack generation along grain boundaries and Ni3+/4+ reactivity that rapidly deteriorate electrochemical performance. Doping and coating have been efficient strategies in delaying the onset of the damage, but they fail to overcome the degradation. There are, however, alternative strategies that directly counter the inherent degradation through micro- and nanostructural modifications of the Ni-rich NCM and NCA cathodes

All-Solid-State Lithium Batteries: Li⁺‑Conducting Ionomer Binder for Dry-Processed Composite Cathodes

All-solid-state lithium batteries (ASSLBs) are considered promising alternatives to current lithium-ion batteries as their use poses less of a safety risk. However, the fabrication of composite cathodes by the conventional slurry (wet) process presents technical challenges, such as limited stability of sulfide electrolytes against organic solvents and the increase of ionic resistance due to the use of insulating polymer binder. Herein, we develop a composite cathode fabricated using a solvent-free (dry) process. The composite cathode is prepared with a Li+-conducting ionomer binder, poly­(tetrafluoroethylene-co-perfluoro­(3-oxa-4-pentenesulfonic acid)) lithium salt. The ionomer facilitates Li+ transport and ensures good interfacial contact between the active material (LiNi0.7Co0.1Mn0.2O2), conducting carbon, and solid electrolyte (Li6PS5Cl) during cycling. Consequently, an ASSLB featuring a composite cathode with an ionomer delivers a high discharge capacity of 180.7 mAh g–1 (3.05 mAh cm–2) at 0.1 C and demonstrates stable cycling performance, retaining 90% of its initial capacity after 300 cycles at 0.5 C

Beyond Doping and Coating: Prospective Strategies for Stable High-Capacity Layered Ni-Rich Cathodes

This Perspective discusses the prospective strategies for overcoming the stability and capacity trade-off associated with increased Ni content in layered Ni-rich Li­[NixCoyMnz]­O2 (NCM) and Li­[NixCoyAlz]­O2 (NCA) cathodes. The Ni-rich NCM and NCA cathodes have largely replaced the LiCoO2 cathodes in commercial batteries because of their lower cost, higher energy density, good rate capability, and reliability that has been extensively field-tested. Nevertheless, they suffer from microcrack generation along grain boundaries and Ni3+/4+ reactivity that rapidly deteriorate electrochemical performance. Doping and coating have been efficient strategies in delaying the onset of the damage, but they fail to overcome the degradation. There are, however, alternative strategies that directly counter the inherent degradation through micro- and nanostructural modifications of the Ni-rich NCM and NCA cathodes

Beyond Doping and Coating: Prospective Strategies for Stable High-Capacity Layered Ni-Rich Cathodes

This Perspective discusses the prospective strategies for overcoming the stability and capacity trade-off associated with increased Ni content in layered Ni-rich Li­[NixCoyMnz]­O2 (NCM) and Li­[NixCoyAlz]­O2 (NCA) cathodes. The Ni-rich NCM and NCA cathodes have largely replaced the LiCoO2 cathodes in commercial batteries because of their lower cost, higher energy density, good rate capability, and reliability that has been extensively field-tested. Nevertheless, they suffer from microcrack generation along grain boundaries and Ni3+/4+ reactivity that rapidly deteriorate electrochemical performance. Doping and coating have been efficient strategies in delaying the onset of the damage, but they fail to overcome the degradation. There are, however, alternative strategies that directly counter the inherent degradation through micro- and nanostructural modifications of the Ni-rich NCM and NCA cathodes

Microstructure- and Interface-Modified Ni-Rich Cathode for High-Energy-Density All-Solid-State Lithium Batteries

Electric vehicles powered by Li-ion batteries pose a potential safety risk because the flammable liquid electrolytes can, under certain conditions, cause explosions. All-solid-state batteries (ASSBs) are safe alternative battery technologies. However, realizing high-energy-density ASSBs by employing Ni-rich layered cathodes is difficult because of the detrimental volume contraction near charge end. This study shows that the simultaneous B doping and coating of a Ni-rich Li[Ni0.9Co0.05Mn0.05]O2 cathode, which modifies the cathode microstructure and cathode–solid electrolyte interface, respectively, afford an ASSB that cycles stably for 300 cycles with minimal capacity fading. An ASSB featuring the B-doped, B-coated Li[Ni0.9Co0.05Mn0.05]O2 cathode demonstrates a discharge capacity of 214 mAh g–1, which represents one of the highest discharge capacities achieved by an ASSB; moreover, the ASSB retains 91% of its initial capacity after 300 cycles and easily outperforms previously reported ASSBs in terms of energy density without compromising cycling stability

Coiled Conformation Hollow Carbon Nanosphere Cathode and Anode for High Energy Density and Ultrafast Chargeable Hybrid Energy Storage

Lithium-ion batteries and pseudocapacitors are nowadays popular electrochemical energy storage for many applications, but their cathodes and anodes are still limited to accommodate rich redox ions not only for high energy density but also sluggish ion diffusivity and poor electron conductivity, hindering fast recharge. Here, we report a strategy to realize high-capacity/high-rate cathode and anode as a solution to this challenge. Multiporous conductive hollow carbon (HC) nanospheres with microporous shells for high capacity and hollow cores/mesoporous shells for rapid ion transfer are synthesized as cathode materials using quinoid:benzenoid (Q:B) unit resins of coiled conformation, leading to ∼5-fold higher capacities than benzenoid:benzenoid resins of linear conformation. Also, Ge-embedded Q:B HC nanospheres are derived as anode materials. The atomic configuration and energy storage mechanism elucidate the existence of mononuclear GeOx units giving ∼7-fold higher ion diffusivity than bulk Ge while suppressing volume changes during long ion-insertion/desertion cycles. Moreover, hybrid energy storage with a Q:B HC cathode and Ge–Q:B HC anode exploit the advantages of capacitor-type cathode and battery-type anode electrodes, as exhibited by battery-compatible high energy density (up to 285 Wh kg–1) and capacitor-compatible ultrafast rechargeable power density (up to 22 600 W kg–1), affording recharge within a minute

Coiled Conformation Hollow Carbon Nanosphere Cathode and Anode for High Energy Density and Ultrafast Chargeable Hybrid Energy Storage

Lithium-ion batteries and pseudocapacitors are nowadays popular electrochemical energy storage for many applications, but their cathodes and anodes are still limited to accommodate rich redox ions not only for high energy density but also sluggish ion diffusivity and poor electron conductivity, hindering fast recharge. Here, we report a strategy to realize high-capacity/high-rate cathode and anode as a solution to this challenge. Multiporous conductive hollow carbon (HC) nanospheres with microporous shells for high capacity and hollow cores/mesoporous shells for rapid ion transfer are synthesized as cathode materials using quinoid:benzenoid (Q:B) unit resins of coiled conformation, leading to ∼5-fold higher capacities than benzenoid:benzenoid resins of linear conformation. Also, Ge-embedded Q:B HC nanospheres are derived as anode materials. The atomic configuration and energy storage mechanism elucidate the existence of mononuclear GeOx units giving ∼7-fold higher ion diffusivity than bulk Ge while suppressing volume changes during long ion-insertion/desertion cycles. Moreover, hybrid energy storage with a Q:B HC cathode and Ge–Q:B HC anode exploit the advantages of capacitor-type cathode and battery-type anode electrodes, as exhibited by battery-compatible high energy density (up to 285 Wh kg–1) and capacitor-compatible ultrafast rechargeable power density (up to 22 600 W kg–1), affording recharge within a minute

Doping Strategy in Developing Ni-Rich Cathodes for High-Performance Lithium-Ion Batteries

Doping is indispensable for ensuring the long-term cycling stability of the Ni-rich layered cathodes. However, using a single type of dopant limits the development of a stable, high-energy cathode material in a single shot. In this study, a dual doping strategy using Al3+ and Nb5+ ions was adopted to improve the cycling stability of Li[Ni0.92Co0.04Mn0.04]O2 (NCM92) cathode; Al3+ doping fortifies the crystal structure, while Nb5+ doping optimized the morphology of the primary particles. The dual doping strategy not only combines the benefits of both dopants simultaneously but also demonstrates excellent performance enhancement through synergistic effects. The Li[Ni0.905Co0.04Mn0.04Al0.005Nb0.01]O2 (AlNb-NCM92) cathode, which was developed through the dual doping of Al and Nb, exhibited remarkable stability, retaining 88.3% of its initial capacity even after 1000 cycles. This result suggests that the doping strategy needs to comprehensively consider both the crystal structure and the microstructure to maximize the long-term cycling stability of high-energy Ni-rich cathode materials