Niobium tungsten oxide can be used as the positive electrode of lithium ion battery, which makes the lithium ion battery have higher power and faster charging speed. The new batteries could be adapted to more new devices, such as electric vehicles and grid-level storage for renewable energy. The battery has three parts: the anode, the cathode and the electrolyte connecting the poles. When a lithium-ion battery discharges, the ions move from the cathode to the anode, and when it is charged, from the anode to the cathode. The faster the lithium ions in the battery move, the faster the battery charges, and the higher the power in the process.
The most common way to increase the speed of the flow of lithium ions is to make the electrode particles into nanoparticles to shorten the distance that lithium ions need to pass through. However, there are some challenges with this approach. Nanoparticles are difficult to pack tightly together, which limits the amount of energy stored in each cell. It can also lead to more side effects, so the battery life won't be long. In addition, the production of nanoparticles also requires high costs.
Senior author Clare Grey, a materials chemist at the university of Cambridge, and her colleagues studied niobium tungsten oxide. They note that these materials have a rigid open crystalline structure, which allows lithium ions to flow rapidly through them, even in relatively large micron sized particles.
The researchers also noted that niobium tungsten oxide, in addition to helping make higher-power batteries, can also reduce battery voltage. While energy can pass in and out of these niobium tungsten oxides quickly, the new batteries involve less energy per unit of time than traditional anode materials.
Low battery voltage can make batteries safer. For example, most lithium batteries contain graphite anodes. The electrical properties of graphite lead to higher battery voltage, but also form elongated lithium metal fibers, known as dendrites, during high-speed charging. These dendrites cause short circuits and further cause batteries to catch fire and explode. "" as a result, lower voltage batteries, such as our batteries, need to be used for high-speed rechargeable batteries.
