Lithium polymer battery | EPFL Graph Search

A lithium polymer battery, or more correctly lithium-ion polymer battery (abbreviated as LiPo, LIP, Li-poly, lithium-poly and others), is a rechargeable battery of lithium-ion technology using a polymer electrolyte instead of a liquid electrolyte. High conductivity semisolid (gel) polymers form this electrolyte. These batteries provide higher specific energy than other lithium battery types and are used in applications where weight is a critical feature, such as mobile devices, radio-controlled aircraft and some electric vehicles. Lithium-ion battery#History LiPo cells follow the history of lithium-ion and lithium-metal cells which underwent extensive research during the 1980s, reaching a significant milestone with Sony's first commercial cylindrical Li-ion cell in 1991. After that, other packaging forms evolved, including the flat pouch format. Lithium polymer cells have evolved from lithium-ion and lithium-metal batteries. The primary difference is that instead of using a liquid lithium-salt electrolyte (such as LiPF6) held in an organic solvent (such as EC/DMC/DEC), the battery uses a solid polymer electrolyte (SPE) such as poly(ethylene oxide) (PEO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA) or poly(vinylidene fluoride) (PVdF). In the 1970s the original polymer design used a solid dry polymer electrolyte resembling a plastic-like film, replacing the traditional porous separator that is soaked with electrolyte. The solid electrolyte can typically be classified as one of three types: dry SPE, gelled SPE and porous SPE. The dry SPE was the first used in prototype batteries, around 1978 by Michel Armand, and 1985 by ANVAR and Elf Aquitaine of France, and Hydro-Québec of Canada. From 1990 several organisations like Mead and Valence in the United States and GS Yuasa in Japan developed batteries using gelled SPEs. In 1996, Bellcore in the United States announced a rechargeable lithium polymer cell using porous SPE. A typical cell has four main components: positive electrode, negative electrode, separator and electrolyte.

Enhanced rate performance of lithium-ion battery anodes using a cobalt-incorporated carbon conductive agent

Xile Hu, Albert Claude Jean-Pierre Daubry, Ming Yang

Lithium-ion batteries with enhanced rate performance are of crucial importance for practical applications. Extensive studies on the structural design and surface modification of electrode materials with the aim of improving the rate performance have been reported. Here we describe a new concept to enhance the rate capability by incorporating a tiny amount of metal species into the electron conductive agent. We show that the Si/C composite anode exhibits increased capabilities at high current densities when oxidized Ketjen black (KJB) with incorporated cobalt (Co-ox-KJB) is used as the electron conductive agent. Compared with the pristine KJB, the reversible capacities of the Si/C electrode with the Co-ox-KJB are increased by 180% on average at 1.50 A g(-1) (279 mA h g(-1)vs. 73 mA h g(-1), respectively). A synergistic contribution from enhanced electron conductivity by Co incorporation, improved affinity towards the electrolyte and an enhanced desolvation process by surface functional groups is responsible for the improved electrochemical performance. This approach is applicable for super P-based electron conductive agents as well.

ROYAL SOC CHEMISTRY2022

Atomic doping & coating for Electrocatalysis & Li-ion batteries

Albert Claude Jean-Pierre Daubry

molybdenum atomic-doping on bio-waste derived nitrogen-doped conductive carbon electrocatalyst was synthesized and investigated for the dinitrogen reduction to ammonia in alkaline media. The assessment of the catalytic activity was found to be non-trivial as nearly any external source can be the cause of ammonia contamination. In a closed-cell set-up using isotopically labelled 15N2 as feed gas for 48h chronoamperometry at -0.1 V vs RHE that the current density was correlated to the availability of the gas. Non-precious metals were incorporated in an oxidized carbon black conductive matrix and investigated for their activity towards oxygen evolution reaction in 0.1 M H2SO4, 0.5 M H2SO4 and 0.1 M HClO4. The stability of the deposited catalyst was insufficient and their deterioration was attributed to the oxidation of the carbon support as well as the dissolution of the metal ions upon high anodic potentials.The same metal-incorporated oxidized conductive carbon black agents were investigated for the enhancement of the performance of Si/C anodes in lithium-ion batteries. It was found that cobalt incorporation in the oxidized matrix displayed a significant influence in the electrochemical kinetics and consequent rate performances. With 0.8% cobalt ions by mass incorporated in oxidized KetJen Black the average capacity of the Si/C anode was increased by 180% at 1.5 A.g-1. This metal incorporation approach was extended to other ionic species (copper, iron and nickel) and other carbon conductive agents (SuperP). The electrolyte affinity, the desolvation process and the improved electronic conductivity synergistically improved the rate performance without compromising the gravimetric capacity of the electrode.The deposition of ultra-thin aluminium oxide by atomic layered deposition on the surface of LiNi0.5Co0.2Mn0.3O2 cathode material in lithium-ion batteries for the improvement of cyclic performances at high voltages (4.3-4.6 V) was investigated. One source of the failure mechanisms of the battery comes from unwanted side reactions between surface species and the electrolyte. The aluminium oxide layers of 1.42 nm and 2,36 nm were found to be beneficial at current densities exceeding 1.0 C (1 C = 170 mAh.g-1), and especially at 5.0 C with an increase of about 20 mAh.g-1 and 35 mAh.g-1 compared to uncoated NCM523, respectively. The capacity retention was found to be improved for all coated samples compared to pristine upon 140 cycles at 1.0 C. Mitigating side reactions and increasing the specific capacity at higher C-rates by atomically controlled layered deposition of inexpensive metal oxides is desirable for the implementation next-generation of safer and stable fast-charging high-voltage lithium-ion batteries.

EPFL2022

The Application of Fuel-Cell and Battery Technologies in Unmanned Aerial Vehicles (UAVs): A Dynamic Study

Jan Van Herle, Hossein Pourrahmani, Claire Marie Isabelle Bernier

The harmful impacts of fossil-fuel-based engines on the environment have resulted in the development of other alternatives for different types of vehicles. Currently, batteries and fuel cells are being used in the automotive industry, while promising progress in the maritime and aerospace sectors is foreseen. As a case study in the aerospace sector, an unmanned aerial vehicle (UAV) was considered. The goal and the novelty of this study are in its analysis of the possibility of providing 960 W of power for a UAV with a weight of 14 kg using a hybrid system of a lithium-ion (Li-ion) battery and proton-exchange membrane fuel cell (PEMFC). The dynamic performance of the system was analyzed considering three different load profiles over time in an optimized condition. PEMFC was the main supplier of power, while the battery intervened when the power load was high for the PEMFC and the system demanded an immediate response to the changes in power load. Additionally, the impacts of the operating temperature and the C-rate of the battery were characterized by the state of the charge of the battery to better indicate the overall performance of the system.

MDPI2022

Atomic doping & coating for Electrocatalysis & Li-ion batteries

Albert Claude Jean-Pierre Daubry

EPFL2022