[Liu, Chang; Li, Feng; Ma, Lai-Peng; Cheng, Hui-Ming] Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, Shenyang 110016, Peoples R China.;Cheng, HM (reprint author), Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, 72 Wenhua Rd, Shenyang 110016, Peoples R China;cheng@imr.ac.cn

Advanced Materials for Energy Storage

Electrolytes and interphases in Li-ion batteries and beyond.

Energy-storage technologies, including electrical double-layer capacitors and rechargeable batteries, have attracted significant attention for applications in portable electronic devices, electric vehicles, bulk electricity storage at power stations, and “load leveling” of renewable sources, such as solar energy and wind power. Transforming lithium batteries and electric double-layer capacitors requires a step change in the science underpinning these devices, including the discovery of new materials, new electrochemistry, and an increased understanding of the processes on which the devices depend. The Review will consider some of the current scientific issues underpinning lithium batteries and electric double-layer capacitors.

Challenges Facing Lithium Batteries and Electrical Double‐Layer Capacitors

Thermal runaway mechanism of lithium ion battery for electric vehicles: A review

Recent developments in cathode materials for lithium ion batteries

Battery industries and research groups are further investigating LiCoO2 to unravel the capacity at high-voltages (>4.3 vs Li). The research trends are towards the surface modification of the LiCoO2 and stabilize it structurally and chemically. In this report, the recent progress in the surface-coating materials i.e., single-element, binary, and ternary hybrid-materials etc. and their coating methods are illustrated. Further, the importance of evaluating the surface-coated LiCoO2 in the Li-ion full-cell is highlighted with our recent results. Mg,P-coated LiCoO2 full-cells exhibit excellent thermal stability, high-temperature cycle and room-temperature rate capabilities with high energy-density of ≈1.4 W h cc−1 at 10 C and 4.35 V. Besides, pouch-type full-cells with high-loading (18 mg cm−2) electrodes of layered-Li(Ni,Mn)O2 -coated LiCoO2 not only deliver prolonged cycle-life at room and elevated-temperatures but also high energy-density of ≈2 W h cc−1 after 100 cycles at 25 °C and 4.47 V (vs natural graphite). The post-mortem analyses and experimental results suggest enhanced electrochemical performances are attributed to the mechanistic behaviour of hybrid surface-coating layers that can mitigate undesirable side reactions and micro-crack formations on the surface of LiCoO2 at the adverse conditions. Hence, the surface-engineering of electrode materials could be a viable path to achieve the high-energy Li-ion cells for future applications.

Surface engineering strategies of layered LiCoO2 cathode material to realize high-energy and high-voltage li-ion cells

Cathode material degradation during cycling is one of the key obstacles to upgrading lithium-ion and beyond-lithium-ion batteries for high-energy and varied-temperature applications. Herein, we highlight recent progress in material surface-coating as the foremost solution to resist the surface phase-transitions and cracking in cathode particles in mono-valent (Li, Na, K) and multi-valent (Mg, Ca, Al) ion batteries under high-voltage and varied-temperature conditions. Importantly, we shed light on the future of materials surface-coating technology with possible research directions. In this regard, we provide our viewpoint on a novel hybrid surface-coating strategy, which has been successfully evaluated in LiCoO2 -based-Li-ion cells under adverse conditions with industrial specifications for customer-demanding applications. The proposed coating strategy includes a first surface-coating of the as-prepared cathode powders (by sol-gel) and then an ultra-thin ceramic-oxide coating on their electrodes (by atomic-layer deposition). What makes it appealing for industry applications is that such a coating strategy can effectively maintain the integrity of materials under electro-mechanical stress, at the cathode particle and electrode- levels. Furthermore, it leads to improved energy-density and voltage retention at 4.55 V and 45 °C with highly loaded electrodes (≈24 mg.cm-2 ). Finally, the development of this coating technology for beyond-lithium-ion batteries could be a major research challenge, but one that is viable.

Feasibility of Cathode Surface Coating Technology for High-Energy Lithium-ion and Beyond-Lithium-ion Batteries

Among the various Ni-based layered oxide systems in the form of LiNi1-y-zCoyAlzO2 (NCA), the compostions between y = 0.1–0.15, z = 0.05 are the most successful and commercialized cathodes used in electric vehicles (EVs) and hybrid electric vehicles (HEVs). However, tremendous research effort has been dedicted to searching for better composition in NCA systems to overcome the limitations of these cathodes, particularly those that arise when they are used use at high discharge/charge rates (>5C) and in high temperature (60 °C) environments. In addition, improving the thermal stability at 4.5 V is also very important in terms of the total amount of heat generated and the onset temperature. Here, a new NCA composition in the form of LiNi0.81Co0.1Al0.09O2 (y = 0.1, z = 0.09) is reported for the first time. Compared to the LiNi0.85Co0.1Al0.05O2 cathode, LiNi0.81Co0.1Al0.09O2 exhibits an excellent rate capability of 155 mAh g−1 at 10 C with a cut-off voltage range between 3 and 4.5 V, corresponding to 562 Wh kg−1 at 24 °C. It additionally provides significantly improved thermal stability and electrochemical performance at the high temperature of 60 °C, with a discharge capacity of 122 mAh g−1 after 200 cycles with capacity retention of 59%.

A New High Power LiNi0.81Co0.1Al0.09O2 Cathode Material for Lithium‐Ion Batteries

The effect of LiCoO 2 cathode nanoparticle size on high-rate performance in Li-ion batteries was investigated using hydrothermally prepared oleylamine-capped LiCoO 2 nanoparticles with a particle size of 50 nm obtained at 200°C. Upon annealing as-prepared LiCoO 2 at 500, 700, and 900°C, the particle size increased to 100 nm, 300 nm, and 1 μm, respectively. Ex situ transmission electron microscopy and X-ray diffraction results indicated that the thickness of the solid electrolyte interface (SEI) affected the particle's electrochemical properties at high rates. A LiCoO 2 cathode with a smaller particle size had a thicker SEI layer, which acted as a barrier for Li-ion diffusion, resulting in deteriorated rate capabilities at higher C rates. However, irrespective of the particle size, there was no structural degradation after cycling. Rate capability tests were performed under two different electrode densities (3.4 and 2.8 g/cm 3 ), and LiCoO 2 with a particle size of 300 nm demonstrated the best rate capability at higher C rates. Upon extended cycling at the 7 C rate, L'CoO 2 with a particle size of 300 nm exhibited 87 and 150 mAh/g under 3.4 and 2.8 g/cm 3 , respectively.

https://iopscience.iop.org/article/10.1149/1.3111031/pdf

Effect of LiCoO2 Cathode Nanoparticle Size on High Rate Performance for Li-Ion Batteries

In order to overcome the inherent structural instability of bare LixNi0.8Co0.15Al0.05O2 (BNCA) containing large amounts of LiOH and Li2CO3 impurities at 60 and >200 °C, an effective nanoscale layer was generated by coating BNCA with an ammonium vanadate precursor, followed by annealing at 400 °C. This process forms a 17 nm thick surface layer containing V4+ ions in the transition metal 3b sites, thereby decreasing the thickness of the cation-mixing layer, which is the main factor responsible for destabilizing the surface structure. Such a coating also helps in substantially reducing the amount of surface impurities of LiOH, Li2CO3, and H2O by forming LiVO2, LiV2O5, VO2, and V2O5. Consequently, at 60 °C, vanadium-treated LiNi0.8Co0.15Al0.05O2 (VNCA) demonstrated excellent cyclability with a discharge capacity of 179 mA h g−1 after 200 cycles (after 17 days) between 3 and 4.3 V, corresponding to 90% capacity retention, which is 18% higher than the capacity retention measured for BNCA. More importantly, VNCA exhibits a significantly reduced heat generation and a higher onset temperature for exothermic reactions.

Minki Jo

Papers

Surface engineering strategies of layered LiCoO2 cathode material to realize high-energy and high-voltage li-ion cells

Feasibility of Cathode Surface Coating Technology for High-Energy Lithium-ion and Beyond-Lithium-ion Batteries

A New High Power LiNi0.81Co0.1Al0.09O2 Cathode Material for Lithium‐Ion Batteries

Effect of LiCoO2 Cathode Nanoparticle Size on High Rate Performance for Li-Ion Batteries

The role of nanoscale-range vanadium treatment in LiNi0.8Co0.15Al0.05O2 cathode materials for Li-ion batteries at elevated temperatures