Ulvestad Andrew, Clark Jesse N, Singer Andrej, Vine David, Cho H M, Harder Ross, Meng Ying Shirley, Shpyrko Oleg G
Department of Physics, University of California-San Diego, La Jolla, California 92093-0319, USA.
Phys Chem Chem Phys. 2015 Apr 28;17(16):10551-5. doi: 10.1039/c5cp00372e.
Lithium ion batteries are the dominant form of energy storage in mobile devices, increasingly employed in transportation, and likely candidates for renewable energy storage and integration into the electrical grid. To fulfil their powerful potential, electrodes with increased capacity, faster charge rates, and longer cycle life must be developed. Understanding the mechanics and chemistry of individual nanoparticles under in situ conditions is a crucial step to improving performance and mitigating damage. Here we reveal three-dimensional strain evolution within a single nanoparticle of a promising high voltage cathode material, LiNi0.5Mn1.5O4, under in situ conditions. The particle becomes disconnected during the second charging cycle. This is attributed to the formation of a cathode electrolyte interphase layer with slow ionic conduction. The three-dimensional strain pattern within the particle is independent of cell voltage after disconnection, indicating that the particle is unable to redistribute lithium within its volume or to its neighbours. Understanding the disconnection process at the single particle level and the equilibrium or non-equilibrium state of nanoparticles is essential to improving performance of current and future electrochemical energy storage systems.
锂离子电池是移动设备中能量存储的主要形式，在交通运输领域的应用越来越广泛，并且很有可能用于可再生能源存储以及并入电网。为充分发挥其强大潜力，必须研发出容量更大、充电速度更快且循环寿命更长的电极。了解原位条件下单个纳米颗粒的力学和化学性质是提高性能和减轻损害的关键一步。在此，我们揭示了一种很有前景的高压阴极材料LiNi0.5Mn1.5O4的单个纳米颗粒在原位条件下的三维应变演变。该颗粒在第二次充电循环期间发生断开。这归因于形成了离子传导缓慢的阴极电解质界面层。颗粒断开后，其内部的三维应变模式与电池电压无关，这表明该颗粒无法在其体积内或与相邻颗粒之间重新分配锂。了解单个颗粒水平上的断开过程以及纳米颗粒的平衡或非平衡状态对于提高当前和未来电化学储能系统的性能至关重要。
