State-of-the-art lithium (Li)-ion batteries are approaching their specific energy limits yet are challenged by the ever-increasing demand of today’s energy storage and power applications, especially for electric vehicles. Li metal is considered an ultimate anode material for future high-energy rechargeable batteries when combined with existing or emerging high-capacity cathode materials. However, much current research focuses on the battery materials level, and there have been very few accounts of cell design principles. Here we discuss crucial conditions needed to achieve a specific energy higher than 350 Wh kg−1, up to 500 Wh kg−1, for rechargeable Li metal batteries using high-nickel-content lithium nickel manganese cobalt oxides as cathode materials. We also provide an analysis of key factors such as cathode loading, electrolyte amount and Li foil thickness that impact the cell-level cycle life. Furthermore, we identify several important strategies to reduce electrolyte-Li reaction, protect Li surfaces and stabilize anode architectures for long-cycling high-specific-energy cells. Jun Liu and Battery500 Consortium colleagues contemplate the way forward towards high-energy and long-cycling practical batteries.

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Pathways for practical high-energy long-cycling lithium metal batteries

Lithium-ion batteries have aided the portable electronics revolution for nearly three decades. They are now enabling vehicle electrification and beginning to enter the utility industry. The emergence and dominance of lithium-ion batteries are due to their higher energy density compared to other rechargeable battery systems, enabled by the design and development of high-energy density electrode materials. Basic science research, involving solid-state chemistry and physics, has been at the center of this endeavor, particularly during the 1970s and 1980s. With the award of the 2019 Nobel Prize in Chemistry to the development of lithium-ion batteries, it is enlightening to look back at the evolution of the cathode chemistry that made the modern lithium-ion technology feasible. This review article provides a reflection on how fundamental studies have facilitated the discovery, optimization, and rational design of three major categories of oxide cathodes for lithium-ion batteries, and a personal perspective on the future of this important area. The 2019 Nobel Prize in Chemistry has been awarded to a trio of pioneers of the modern lithium-ion battery. Here, Professor Arumugam Manthiram looks back at the evolution of cathode chemistry, discussing the three major categories of oxide cathode materials with an emphasis on the fundamental solid-state chemistry that has enabled these advances.

/pdf/a-reflection-on-lithium-ion-battery-cathode-chemistry-23v4hynq0w.pdf

A reflection on lithium-ion battery cathode chemistry

High-nickel layered oxide cathode materials will be at the forefront to enable longer driving-range electric vehicles at more affordable costs with lithium-based batteries. A continued push to higher energy content and less usage of costly raw materials, such as cobalt, while preserving acceptable power, lifetime and safety metrics, calls for a suite of strategic compositional, morphological and microstructural designs and efficient material production processes. In this Perspective, we discuss several important design considerations for high-nickel layered oxide cathodes that will be implemented in the automotive market for the coming decade. We outline various intrinsic restraints of maximizing their energy output and compare current/emerging development roadmaps approaching low-/zero-cobalt chemistry. Materials production is another focus, relevant to driving down costs and addressing the practical challenges of high-nickel layered oxides for demanding vehicle applications. We further assess a series of stabilization techniques on their prospects to fulfill the aggressive targets of vehicle electrification. The development of high-nickel layered oxide cathodes represents an opportunity to realize the full potential of lithium-ion batteries for electric vehicles. Manthiram and colleagues review the materials design strategies and discuss the challenges and solutions for low-cobalt, high-energy-density cathodes.

https://www.nature.com/articles/s41560-019-0513-0.pdf?proof=t

High-nickel layered oxide cathodes for lithium-based automotive batteries

Finding a viable electrolyte for next-generation 5 V-class lithium-ion batteries is of primary importance. A long-standing obstacle has been metal-ion dissolution at high voltages. The LiPF6 salt in conventional electrolytes is chemically unstable, which accelerates transition metal dissolution of the electrode material, yet beneficially suppresses oxidative dissolution of the aluminium current collector; replacing LiPF6 with more stable lithium salts may diminish transition metal dissolution but unfortunately encounters severe aluminium oxidation. Here we report an electrolyte design that can solve this dilemma. By mixing a stable lithium salt LiN(SO2F)2 with dimethyl carbonate solvent at extremely high concentrations, we obtain an unusual liquid showing a three-dimensional network of anions and solvent molecules that coordinate strongly to Li(+) ions. This simple formulation of superconcentrated LiN(SO2F)2/dimethyl carbonate electrolyte inhibits the dissolution of both aluminium and transition metal at around 5 V, and realizes a high-voltage LiNi0.5Mn1.5O4/graphite battery that exhibits excellent cycling durability, high rate capability and enhanced safety.

Superconcentrated Electrolytes for a High-Voltage Lithium-Ion Battery

A critical challenge in the commercialization of layer-structured Ni-rich materials is the fast capacity drop and voltage fading due to the interfacial instability and bulk structural degradation of the cathodes during battery operation. Herein, with the guidance of theoretical calculations of migration energy difference between La and Ti from the surface to the inside of LiNi0.8Co0.1Mn0.1O2, for the first time, Ti-doped and La4NiLiO8-coated LiNi0.8Co0.1Mn0.1O2 cathodes are rationally designed and prepared, via a simple and convenient dual-modification strategy of synchronous synthesis and in situ modification. Impressively, the dual modified materials show remarkably improved electrochemical performance and largely suppressed voltage fading, even under exertive operational conditions at elevated temperature and under extended cutoff voltage. Further studies reveal that the nanoscale structural degradation on material surfaces and the appearance of intergranular cracks associated with the inconsistent evolution of structural degradation at the particle level can be effectively suppressed by the synergetic effect of the conductive La4NiLiO8 coating layer and the strong TiO bond. The present work demonstrates that our strategy can simultaneously address the two issues with respect to interfacial instability and bulk structural degradation, and it represents a significant progress in the development of advanced cathode materials for high-performance lithium-ion batteries.

Simultaneously Dual Modification of Ni-Rich Layered Oxide Cathode for High-Energy Lithium-Ion Batteries

High-Ni layered oxides are promising next-generation cathodes for lithium-ion batteries owing to their high capacity and lower cost. However, as the Ni content increases over 70 %, they have a high dynamic affinity towards moisture and CO2 in ambient air, primarily reacting to form LiOH, Li2 CO3 , and LiHCO3 on the surface, which is commonly termed "residual lithium". Air exposure occurs after synthesis as it is common practice to handle and store them under ambient conditions. The air exposure leads to significant performance losses, and hampers the electrode fabrication, impeding their practical viability. Herein, we show that substituting a small amount of Al for Ni in the crystal lattice notably improves the chemical stability against air by limiting the formation of LiOH, Li2 CO3 , LiHCO3 , and NiO in the near-surface region. The Al-doped high-Ni oxides display a high capacity retention with excellent rate capability and cycling stability after being exposed to air for 30 days.

Modified High-Nickel Cathodes with Stable Surface Chemistry Against Ambient Air for Lithium-Ion Batteries

Preparation of thin film composite nanofiltration membrane with improved structural stability through the mediation of polydopamine

Extending the Service Life of High‐Ni Layered Oxides by Tuning the Electrode–Electrolyte Interphase

The pursuit for high-energy-density batteries has inspired the resurgence of metallic lithium (Li) as a promising anode, yet its practical viability is restricted by the uncontrollable Li dendrite growth and huge volume changes during repeated cycling. Herein, a new 3D framework configured with Mo2 N-mofidied carbon nanofiber (CNF) architecture is established as a Li host via a facile fabrication method. The lithiophilic Mo2 N acts as a homogeneously pre-planted seed with ultralow Li nucleation overpotential, thus spatially guiding a uniform Li nucleation and deposition in the matrix. The conductive CNF skeleton effectively homogenizes the current distribution and Li-ion flux, further suppressing Li-dendrite formation. As a result, the 3D hybrid Mo2 N@CNF structure facilitates a dendrite-free morphology with greatly alleviated volume expansion, delivering a significantly improved Coulombic efficiency of ≈99.2% over 150 cycles at 4 mA cm-2 . Symmetric cells with Mo2 N@CNF substrates stably operate over 1500 h at 6 mA cm-2 for 6 mA h cm-2 . Furthermore, full cells paired with LiNi0.8 Co0.1 Mn0.1 O2 (NMC811) cathodes in conventional carbonate electrolytes achieve a remarkable capacity retention of 90% over 150 cycles. This work sheds new light on the facile design of 3D lithiophilic hosts for dendrite-free lithium-metal anodes.

A 3D Lithiophilic Mo 2 N-Modified Carbon Nanofiber Architecture for Dendrite-Free Lithium-Metal Anodes in a Full Cell

A unique three-dimensional (3D) hybrid architecture configured with vanadium tetrasulfide (VS4) nanomediators uniformly anchored in a reduced graphene oxide scaffold (VS4@RGO) is fabricated as a su...

Jianyu Li

Papers

Modified High-Nickel Cathodes with Stable Surface Chemistry Against Ambient Air for Lithium-Ion Batteries

Preparation of thin film composite nanofiltration membrane with improved structural stability through the mediation of polydopamine

Extending the Service Life of High‐Ni Layered Oxides by Tuning the Electrode–Electrolyte Interphase

A 3D Lithiophilic Mo 2 N-Modified Carbon Nanofiber Architecture for Dendrite-Free Lithium-Metal Anodes in a Full Cell

In-Situ Assembled VS4 as a Polysulfide Mediator for High-Loading Lithium–Sulfur Batteries