锂空气电池（Li-air battery，LAB）具有超高的理论能量密度（11.4 kWh kg^-1），可与汽油相媲美，因而受到广泛关注。然而，正极的放电产物为固态的Li₂O₂，且具有绝缘性，导致正极反应动力学缓慢，从而引发能量密度低、循环寿命短、倍率性能差等系列问题。合理地设计空气正极的产物结构是改善正极氧还原反应（oxygen reduction reaction, ORR）和氧析出反应（oxygen evolution reaction, OER）动力学，提升电池的性能的有效途径。因此，本报告基于电极产物结构设计，围绕自催化锂空气电池（self-catalyzed Li-air battery, SCLAB）体系开展了以下研究：

（1）基于过渡金属-载体相互作用的设计策略，利用电沉积，原位构筑负载亚纳米结构的自催化电极。通过金属载体的合理设计，可控合成亚纳米结构的Co，并实现了电催化性能的提升。实验和理论结果表明，碳平面基底可以与重金属原子强耦合，优化碳骨架的电子结构，并激活活性中心。在ORR和OER中，亚纳米结构具有优越的电催化活性，与纯基底、团簇和纳米粒子结构相比尤为突出。这种特殊的金属载体结构可以有效地调节不同形貌的放电产物，其中，在亚纳米结构电极上生成的纳米片状Li₂O₂具有最佳的电催化活性，同时具有较低的过电位、良好的倍率性能和较长的循环寿命。

（2）突破传统电极设计思路，另辟蹊径，通过电化学原位植入法，将催化活性位点以掺杂的形式植入放电产物Li₂O₂内，从本质上改变Li₂O₂的绝缘性，同时使催化活性位点均匀分散在Li₂O₂基质中，打破传统的固体催化剂和固体产物之间固-固界面限制，构筑具有自催化放电产物（Co-Li_2-xO₂）的LAB体系。首先理论计算模拟了系列金属元素在Li₂O₂中的掺杂，研究了不同掺杂体系的电子结构等，并进一步通过实验研究，清晰了传统LAB、自催化产物体系的区别。通过自催化产物的设计，电池的全容量可高达35000 mAh g^-1，充放电过电势0.84 V，能量效率提高到76.1 %，并实现了3A g^-1的快充性能。

（3）基于自催化产物与氧化还原媒介体（redox mediators, RMs）的协同作用策略，在电池体系中引入乙酰丙酮锰等弱电解质，同时实现产物原位掺杂构筑自催化产物与RM协同优化反应过程的双功能。通过调控添加剂的种类、浓度、体系压力等，系统研究了不同添加剂等对电池性能影响及作用机制。研究结果表明，引入乙酰丙酮盐等弱电解质，可有效提升电池反应动力学，实现长寿命，其中，以乙酰丙酮锰为最佳。在限容条件下（200 mA g^-1电流密度），可实现0.43 V的极低过电势；在1000 mA g^-1的大电流密度下，可实现250圈以上的稳定循环；结合固体催化剂和工作压力的优化，可实现2500的超长循环。

Li-air battery (LAB) has attracted extensive attention because of its ultra-high theoretical energy density (11.4 kWh kg^-1), which is comparable to gasoline. However, the discharge product of the positive electrode is solid Li₂O₂ and insulation with sluggish kinetics of the cathode, resulting in a series of problems such as low energy density, short cycle life and poor rate performance. Reasonable design of the product structure of air cathode is an effective way to improve the kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) and improve the performance of battery. Therefore, based on the structural design of electrode products, the following research has been carried out around the self-catalyzed LAB system.

(1) Based on the strategy of transition metal-support interaction, a self-catalyzed electrode loaded with sub nanostructures was constructed by in-situ electrodeposition. The sub metal structure of Co can be synthesized and the performance of Co can be improved reasonably. The experimental and theoretical results show that the carbon planar substrate can be strongly coupled with heavy metal atoms, optimize the electronic structure of the carbon skeleton and activate the active center. In ORR and OER, sub nanostructures have superior electrocatalytic activity, especially compared with pure substrate, cluster and nano particle structures. This metal-support structure can effectively adjust the discharge products with different morphologies. Among them, the nano flake Li₂O₂ generated on the sub nanostructure electrode has the best electrocatalytic activity, low overpotential, good rate performance and long cycle life.

(2) Break through the traditional electrode design idea and find another way. Through the electrochemical in-situ implantation method, the catalytic active sites are implanted into the discharge product Li₂O₂ in the form of doping, which essentially changes the insulation of Li₂O₂. At the same time, the catalytic active sites are evenly dispersed in the Li₂O₂ matrix, breaking the limitation of the solid-solid interface between the traditional solid catalyst and the solid product, and building a lab system with autocatalytic discharge product (Co-Li_2-xO₂). Firstly, the doping of a series of metal elements in Li₂O₂ is simulated by theoretical calculation, and the electronic structures of different doping systems are studied. Through further experimental research, the differences between traditional LAB and self-catalyzed product systems are clarified. Through the design of self-catalyzed product, the full capacity of the battery can be up to 35000 mAh g^-1, the charge discharge overpotential is 0.84 V, the energy efficiency is increased to 76.1 %, and the fast-charging performance with 3 A g^-1 is realized.

(3) Based on the synergistic strategy of self-catalyzed products and redox mediators (RM), weak electrolytes such as manganese acetylacetonate were introduced into the battery system, and the product was in-situ doped to build a dual function of self-catalyzed products and RM to optimize the reaction process. By adjusting the type, concentration and system pressure of RM, the effect mechanism of different additives on battery performance was systematically studied. The results show that the introduction of weak electrolytes such as acetylacetone salt can effectively improve the reaction kinetics of the battery and achieve long life, among which manganese acetylacetone is the best. Very low overpotential of 0.42 V can be achieved under capacity limiting conditions at 200 mA g^-1. Under the high current density of 1000 mA g^-1, more than 250 cycles of stable cycle can be realized. Combined with the optimization of solid catalyst and working pressure, 2500 ultra long cycle can be realized without obvious capacity and voltage attenuation.