The dual limitations of traditional lithium batteries in terms of energy density and safety have led the industry to focus on solid-state battery technology. As the core direction of the next generation of battery technology, solid-state batteries are regarded as the “ultimate solution” to solve the problem of endurance of humanoid robots due to their high energy density, high safety and long cycle life.
1. Multiple restrictions restrict battery life
Compared with traditional consumer electronics and new energy vehicles, humanoid robots have more stringent performance requirements for lithium battery products. It is understood that many current humanoid robot products have the problem of “long charging time and short battery life”. Due to the limited internal space, the battery volume cannot be expanded infinitely. It is necessary to provide enough energy in a smaller volume and weight to ensure that the robot can run for a long time and complete various complex tasks. In addition, battery safety and stability are also crucial, and it is necessary to have complete overcharge, over-discharge, overheating protection and other functions.
The current industry is at a critical stage where battery performance catches up with market demand, and it is necessary to make collaborative breakthroughs in multiple fields such as materials science, manufacturing engineering, and artificial intelligence.
The key technical bottlenecks that currently restrict the improvement of humanoid robot battery life are mainly reflected in three aspects: battery energy density, high-rate discharge performance, and battery management system (BMS) optimization.
First, the battery energy density is insufficient, making it difficult to meet high energy consumption requirements. The current mainstream lithium battery materials (such as ternary lithium materials) has an energy density of only 240Wh/kg, far below the 400Wh/kg threshold required to achieve longer battery life. Taking Tesla Optimus as an example, its 52V, 2.3kWh battery can only support 2 to 4 hours of exercise, while the high-intensity, high-frequency movements of humanoid robots require a longer-lasting energy supply.
In addition, high-rate discharge leads to performance degradation and safety hazards. The jumping and grabbing movements of humanoid robots require instantaneous high-rate discharge of the battery, but large currents can easily cause severe heating, leading to battery cycle life degradation and thermal runaway risks.
The battery cycle life of a bionic quadruped robot is about 1,000 times, while the battery degradation rate of a humanoid robot is faster due to its more complex movements. In high-frequency and high-load discharge scenarios, it is difficult for existing battery materials system to balance power output and stability.
In addition, the dynamic energy efficiency optimization of the battery management system is insufficient. Traditional BMS has defects in dynamic energy consumption scenarios: in the face of sudden current surges caused by grabbing heavy objects, the existing algorithm cannot match the power output in real time, resulting in energy calculation errors and waste; the kinetic energy generated by robot movements (such as arm swings and downhill walking) is not effectively recovered, further exacerbating energy loss.
These problems need to be solved by AI-enabled BMS, using reinforcement learning to optimize management strategies, and achieve action energy consumption prediction, dynamic power adjustment, and energy recovery.
2. Battery Material and structure innovation
In the field of humanoid robots, the main development direction of lithium battery technology is high-nickel ternary batteries and solid-state batteries. Among them, high-nickel ternary batteries have a high energy density, which can reduce the volume and weight of the battery and increase the power of the robot, while solid-state batteries stand out with excellent safety.
In terms of structural innovation, the square stacking battery process has achieved the ultimate utilization of the internal space of the battery cell by breaking through the limitations of the traditional winding process. This design has greatly improved the battery energy density compared with other batteries using the winding process, providing strong kinetic energy support for the robot.
In terms of material application, the current research and development of new materials such as positive electrode materials-rich lithium manganese-based materials on the market, combined with high-voltage technology, can increase the gram capacity by more than 20%. At present, this technology has entered the experimental stage and is expected to greatly increase the energy density of the battery in the future. There are also continuous innovations in negative electrode materials, and we are committed to the development of high-silicon negative electrode materials. In China, negative electrodes with a silicon content of 10% to 30% have been used in high-energy density projects such as mobile phones and smart wearables. In the future, we will gradually introduce robot projects according to customer needs.
Compared with traditional lithium batteries, solid-state batteries have significant advantages in humanoid robot applications. Solid-state batteries significantly improve energy density and safety by replacing liquid electrolytes with solid electrolytes. The high energy density of solid-state batteries means that more electricity can be stored in the same volume, directly extending the working time of the robot after a single charge. Its non-flammable and non-volatile characteristics greatly reduce the risk of thermal runaway and improve the safety of robot operation.
Some companies have achieved a balance between high performance and lightweight and miniaturization through two major strategies: material innovation and structural optimization, in response to the strict requirements of humanoid robots on battery volume and weight.
At present, in terms of material innovation, the high-nickel ternary positive electrode adopts molecular-level in-situ coating technology to effectively improve the volume energy density;
The positive and negative electrodes adopt a lithium-manganese-rich positive electrode and a lithium-carbon composite negative electrode design, which greatly improves the energy density of the single cell, further reduces the volume of the cell, and better adapts to the narrow space of the humanoid robot’s torso or joints;
In terms of structural optimization, the silicon-based negative electrode adopts a nanoporous structure to improve the compaction density of the pole piece and maximize the utilization of the internal space of the cell.
3. Comprehensive coverage of charging capacity and safety
Safety is the cornerstone of robot applications, especially in complex and changing environments. Building a multi-level safety assurance system from battery cell safety to system active defense has become the focus of battery R&D companies.
Semi-solid batteries use polymer solid electrolytes instead of flammable liquid electrolytes, significantly reducing the risk of thermal runaway. At present, semi-solid batteries have successfully passed safety tests such as acupuncture and overcharging. In addition, the unique battery pack structure design can effectively prevent heat spread. At the same time, it is equipped with the latest AI BMS system, which monitors the health status of the battery in real time through cloud data, realizes fault warning and timely intervention, and reduces safety risks in extreme scenarios.
Efficiency is the life of robots, and the long waiting time for charging has always been a bottleneck for improving productivity. At present, some battery products can achieve 6 minutes to charge to 80% SOC (state of charge), which greatly shortens the charging time of robots. In addition, the advantages of lithium-ion battery PACK solutions, combined with the accumulation of BMS technology, provide mature and reliable power products and solutions that meet the needs of fast charging for many leading humanoid robot manufacturers
Some batteries use composite solid electrolyte technology (oxide + polymer), which provides solid battery material safety for multi-scenario applications of robots. In particular, its electrolyte material has better low-temperature dynamics, and the internal resistance of the battery is reduced by 10% at minus 10°C. This feature lays a material foundation for the application of robot batteries in cold northern regions and solves the pain point of the sudden drop in the endurance of outdoor robots in winter.
In terms of positive and negative electrodes, the ternary positive electrode has high thermal stability and the silicon-based negative electrode has low expansion. The two work together to significantly improve the stability of the battery cell and provide additional emergency response time for the robot in the event of sudden safety hazards.
There are also batteries for special applications, which use solid electrolytes instead of electrolytes to fundamentally eliminate the risk of thermal runaway. Even if the robot undergoes severe plastic deformation and the structure is completely destroyed, it is not easy to catch fire and explode. At the same time, the three-dimensional lithium-carbon composite negative electrode is used in the negative electrode, providing a capacity design of up to 2000mAh/g, which helps to achieve ultra-high specific energy and greatly improve the payload capacity of robots in scenarios such as aerospace.
In terms of charging and discharging efficiency, organic-inorganic composite solid electrolyte technology is used to effectively improve the interface contact of solid-state batteries and reduce the internal resistance of the battery cell. The safety hazards of lithium-ion batteries are solved from the source. The robot terminal can combine corresponding technologies according to specific application scenarios, thereby effectively solving the safety problems of robots in multiple scenarios.
4. The industry chain seeks breakthroughs together
According to the forecast of relevant industry research institutes, by 2035, the global humanoid robot market sales will exceed 5 million units and the market size will exceed 400 billion yuan. This will drive the leap in demand for lithium batteries and form a new market space of hundreds of billions.
At present, Xiaowei New Energy is establishing close cooperation with many well-known robot manufacturers to jointly explore the best solutions for battery materials for robots. “We believe that with the deepening of cooperation, BYD’s solid-state battery materials will be more widely used in the field of robots.” Xiaowei said.
For the future development prospects of the robot battery market, with the advancement of science and technology and the development of society, emerging fields such as low-altitude aircraft and humanoid robots are rapidly emerging, and the demand for high-performance, safe and reliable power systems is growing. The diversified solutions provided by solid-state battery materials can meet the specific needs of different customers, and this market will be further expanded in the future.